Moderators: jsumali2, richierich, ua900, PanAm_DC10, hOMSaR

 
User avatar
Finn350
Posts: 1601
Joined: Tue Jul 09, 2013 4:57 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Fri Mar 13, 2015 8:40 pm

Quoting tailskid (Reply 149):
But it is, if it was put in standby 37 seconds earlier. We can't assume that what happened to MH370 was caused by a dozen little faults.

The timeline of the events is:

1720.31 UTC MH370 over waypoint IGARI
1720.36 UTC MH370 Mode S symbol dropped off
1721.13 UTC The radar position of MH370 dropped off 3.2 Nm after passing IGARI

If it the selector was put in STANDBY at 1720.36, how on earth could the transponder be detected 37 seconds later around 3 Nm off the last position?

It looks like the selector was put in ALT RPTG OFF at 1720.36 UTC and STANDBY at 1721.13 UTC.
 
tailskid
Posts: 844
Joined: Fri Jun 06, 2014 7:27 pm

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Fri Mar 13, 2015 8:49 pm

Quoting Finn350 (Reply 150):
how on earth could the transponder be detected 37 seconds later around 3 Nm off the last position?

My understanding is that putting it in standby only removes the transponder interrogation mode, (what we used to call IFF) but the transponder continues to function.
 
User avatar
Finn350
Posts: 1601
Joined: Tue Jul 09, 2013 4:57 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Fri Mar 13, 2015 8:58 pm

Quoting tailskid (Reply 151):

My understanding is that putting it in standby only removes the transponder interrogation mode, (what we used to call IFF) but the transponder continues to function.

No, "Standby" is effectively "Off" regarding signals, and there is no separate "Off" position.

[Edited 2015-03-13 13:59:41]
 
tailskid
Posts: 844
Joined: Fri Jun 06, 2014 7:27 pm

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Fri Mar 13, 2015 9:04 pm

Quoting Finn350 (Reply 152):
No, "Standby" is effectively "Off" regarding signals, and there is no separate "Off" position.

Yes there is.

https://www.google.com/search?q=boeing+777+transponder+jpg&tbm=isch&imgil=oDpAp0wkNTmYgM%253A%253BQ4Li_gbjuikctM%253Bhttp%25253A%25252F%25252Fwww.meriweather.com%25252Fflightdeck%25252F777%25252Fped%25252Fatc.html&source=iu&pf=m&fir=oDpAp0wkNTmYgM%253A%252CQ4Li_gbjuikctM%252C_&usg=__U9UcHG74YLpdb9uOP6qjW9RBIXY%3D&biw=1920&bih=951&ved=0CCgQyjc&ei=S1ADVdO9MM-WoQT7xYLwCg#imgrc=oDpAp0wkNTmYgM%253A%3BQ4Li_gbjuikctM%3Bhttp%253A%252F%252Fwww.meriweather.com%252Fflightdeck%252F777%252Fped%252Fatc.jpg%3Bhttp%253A%252F%252Fwww.meriweather.com%252Fflightdeck%252F777%252Fped%252Fatc.html%3B515%3B220

(if the link doesn't work, Google boeing 777 transponder jpg)
 
User avatar
Finn350
Posts: 1601
Joined: Tue Jul 09, 2013 4:57 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Fri Mar 13, 2015 9:10 pm



The selector switch positions are:
- STBY
- ALT RPTG OFF
- XPNDR
- TA ONLY
- TA/RA
 
User avatar
Moose135
Posts: 3223
Joined: Mon Oct 04, 2004 11:27 pm

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Fri Mar 13, 2015 9:12 pm

I've come across a couple of images that reportedly are B777 transponders, and they do not have an "Off" position, just Standby and Alt Rptg Off

http://forums.x-plane.org/uploads/monthly_08_2014/post-134107-0-12472000-1407241662.jpg
KC-135 - Passing gas and taking names!
 
tailskid
Posts: 844
Joined: Fri Jun 06, 2014 7:27 pm

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Fri Mar 13, 2015 9:19 pm

It looks like you're right, however above some of the posters were discussing this as if it was possible to turn off mode S and leave the transponder on.

I don't know, I'm not a 777 jockey. Is 7BOEING7 around?
 
User avatar
Finn350
Posts: 1601
Joined: Tue Jul 09, 2013 4:57 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Fri Mar 13, 2015 9:20 pm

Quoting tailskid (Reply 156):
It looks like you're right, however above some of the posters were discussing this as if it was possible to turn off mode S and leave the transponder on.

Yes, it is the ALT RPTG OFF position. Please re-read the 20 or so last posts.
 
tailskid
Posts: 844
Joined: Fri Jun 06, 2014 7:27 pm

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Fri Mar 13, 2015 9:33 pm

I apologize for the confusion. I started today at post 148 and missed the context.
 
User avatar
777Jet
Topic Author
Posts: 6987
Joined: Sat Mar 08, 2014 7:29 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sat Mar 14, 2015 12:24 am

Quoting WingedMigrator (Reply 129):
The interim report has significantly changed my odds:
35% crew oxygen bottle explosion
25% combustive event
10% other technical fault
15% failed hijack
10% captain did it
5% other

If a crew oxygen bottle explosion started the chain of MH370 events, then I take it that you believe the explosion happened between the ATC sign off and the transponder / comms going silent, near IGARI, correct?

I believe that the turns made by MH370 and the SatCom re-log on were made by human inputs. I also believe it has been established that the SatCom re-log on was initiated from the aircraft. Therefore, whilst your opinion might differ, IMHO I believe that somebody was trying to fly the plane at least at the time of the final turn / SatCom re-log on.

My question is:

If the crew's backup oxygen bottle exploded, what would have allowed them to have enough oxygen to remain alive until some point around the time of the final turn / SatCom re-log on but then obviously, eventually, be overcome / suffer hypoxia in order for the plane to fly on by itself for another 6+ hours?

How many hand-held oxygen bottles would the cockpit crew have had access to and for how long would they have lasted?

Quoting YoungMans (Reply 136):
Unlike you, I would never say that the aircraft was not taken by a UFO; because, without actual facts I couldn't.
For starters, the very term implies that we would be dealing with an 'UNIDENTIFIED' flying object.
It does not automatically mean extra terrestrial, or terrestrial but crewed by some unknown entities.
Is it likely? probably not! Is it highly unlikely? I'm pretty sure it would be - but not impossible.
Also, our militaries could and might be up to all sorts of shinanigans and we, the public, wouldn't have the faintest idea.

Do you really think there is a flying object in existence large enough to simple take MH370??? Seriously???

And I'm talking about 'taking the aircraft physically' when I said MH370 was not taken by UFOs. I was not referring to the possibility of a remote takeover by an aircraft flying in close proximity...

Quoting YoungMans (Reply 136):
So, in that sense, and as I have mentioned it already, there is even a possibility, however remote, that the aircraft may have been shot down.

And, just to clarify, do you still entertain the idea that MH370 was vaporized by some kind of nuclear device / lazer that would leave no trace of the aircraft behind when you say "shot down"???

[Edited 2015-03-13 17:29:08]
DC10-10/30,MD82/88/90, 717,727,732/3/4/5/7/8/9ER,742/4,752/3,763/ER,772/E/L/3/W,788/9, 306,320,321,332/3,346,359,388
 
AIRWALK
Posts: 241
Joined: Fri Jun 06, 2014 9:33 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sat Mar 14, 2015 1:12 am

Quoting 777Jet (Reply 159):
How many hand-held oxygen bottles would the cockpit crew have had access to and for how long would they have lasted?

If by hand-held you mean portable oxygen bottles, they are located in the cabin not in the flight deck. There are a total of 15 located throughout the cabin.

For the flight crew the oxygen is supplied by two cylinders which hold approx 3150 litres each. There are four oxygen masks in the cockpit in total that are fed by these tanks. These tanks are separate so if one were to rupture, the crew would still have an oxygen feed. The expected duration for oxygen with both tanks operational is approximately 27 hours for one crew member and 13 hours for two. (unpressurized cabin with aircraft altitude of 36,000ft)
I'm sure this thread will take off soon
 
User avatar
777Jet
Topic Author
Posts: 6987
Joined: Sat Mar 08, 2014 7:29 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sat Mar 14, 2015 2:20 am

Quoting AIRWALK (Reply 160):
If by hand-held you mean portable oxygen bottles, they are located in the cabin not in the flight deck. There are a total of 15 located throughout the cabin.

If the cockpit crew had a problem with their backup oxygen supply after some kind of event then they must have had no choice other than to attempt to access some of the portable oxygen bottles - either by sending one pilot to go and fetch them or by ordering the FAs to bring them - who knows how but I assume they would try if it meant life or death. I would assume that at the last resort the pilots would attempt to access some of those bottles for themselves at all costs - because without pilots the plane is doomed - the pilots should have priority to life saving measures. That is why I am wondering how long just one portable bottle would last each pilot. I am trying to make sense of any scenario in which the crew would only have enough oxygen to get from near IGARI when something happened to the point in time in which the final turn was made & the SatCom re-log happened assuming they passed out from a lack of oxygen after then...

Quoting AIRWALK (Reply 160):
For the flight crew the oxygen is supplied by two cylinders which hold approx 3150 litres each. There are four oxygen masks in the cockpit in total that are fed by these tanks. These tanks are separate so if one were to rupture, the crew would still have an oxygen feed. The expected duration for oxygen with both tanks operational is approximately 27 hours for one crew member and 13 hours for two. (unpressurized cabin with aircraft altitude of 36,000ft)

So even if one tank ruptured, if the other tank was still functioning it should last two pilots for about 3.5 hours. 3.5 hours from near IGARI places the aircraft well beyond the point in time & area in which it could be argued that inputs such as turns were being made by somebody.

I just can't see how an explosion of just one of the crew's backup oxygen bottles in the EE Bay fits in with the timeframe, which, IMHO, suggests that somebody was attempting to fly the plane at the time of the final turn / SatCom re-log.

Either just one bottle was out of action giving both pilots about 3.5 hours of oxygen each from the other bottle - which is a much longer timeframe than the hour or so past IGARI in which the final turn / SatCom re-log took place and also could signal the last actions of humans before they passed out. I find this scenario hard to believe given that it could be argued that inputs were only made for about 1hr after the event near IGARI (the turns / SatCom re-log) despite the crew possibly having oxygen to continue on for another 2.5 hours with the one good bottle that did not rupture. Maybe the one good bottle the crew were depending on also failed around the SatCom re-log time? That's the only way I'd buy into that scenario.

Or one or both backup bottles were out of action / ruptured but the plane remained pressurized normally and thus the backup oxgyen supply was irrelevant anyway and breathing could continue as normal. I find this scenario hard to believe given that human input eventually seemed to stop about 1hr after the 'event' near IGARI and the plane flew on for hours more.

Or both backup bottles ruptured and the explosion caused depressurization. The crew realized that their masks were not working and most likely the FO was very quickly sent to fetch a portable bottle from the cabin for each of the pilots to use. That gave the crew X ammount of time and lasted until just after the final turn & SatCom re-log - after then the two portable oxygem bottles the crew fetched from the cabin ran out and they passed out. Again, the problem I have with this scenario is... the crew would have known how long the portable bottles would last and I have no doubt they would have attempted to land before that time. It does not make sense for a crew with X ammount of time of oxygen left to not attempt to land within this time frame. But they continued on away from the area they know.

I'm just not so sure about the 'crew backup oxygen bottle explosion in the EE bay' scenario.   

[Edited 2015-03-13 19:30:38]
DC10-10/30,MD82/88/90, 717,727,732/3/4/5/7/8/9ER,742/4,752/3,763/ER,772/E/L/3/W,788/9, 306,320,321,332/3,346,359,388
 
User avatar
7BOEING7
Posts: 3039
Joined: Fri Oct 12, 2012 5:28 pm

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sat Mar 14, 2015 3:32 am

If the flight crew oxygen system failed causing a rapid depressurization, the flight crew would have between 30-60 seconds (approximately) of useful consciousness to determine their masks were inoperative and make a break for the portable bottles, several of which would be found just outside the cockpit door in the galley and by door 1L. If a pilot was able to get to a bottle and activate it (odds of that very slim) he could grab another bottle, return to the cockpit, start an emergency descent and get the other pilot on oxygen.

If both pilots were busy going through procedures, didn't notice their oxygen wasn't functional and lost consciousness, there's a chance one of the FA's would have realized they were not doing a rapid descent, gone to the cockpit to determine what was going on and finding the crew passed out they would have grabbed a couple of portable bottles and brought them back to life.

But the fact that the airplane continued on a path that indicated somebody was in control but didn't descend would indicate it wasn't a pressurization failure.
 
WingedMigrator
Posts: 1771
Joined: Wed Oct 26, 2005 9:45 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sat Mar 14, 2015 3:49 am

Quoting Moose135 (Reply 155):
I've come across a couple of images that reportedly are B777 transponders, and they do not have an "Off" position, just Standby and Alt Rptg Off

By focusing only on the user interface and what front panel knobs can be turned or what buttons can be pressed to achieve the known outcome, we may be missing half of the ways that a system can be altered or disabled. There are surely ways to make things behave differently or fail completely by disconnecting these cockpit interface units from their respective avionics boxes down below. In a complex system the front panel is just the tip of the iceberg; to consider only that is to miss the bigger picture.

Quoting 777Jet (Reply 159):
I take it that you believe the explosion happened between the ATC sign off and the transponder / comms going silent, near IGARI, correct?

Under this particular scenario, yes.

Quoting 777Jet (Reply 159):
IMHO I believe that somebody was trying to fly the plane at least at the time of the final turn / SatCom re-log on.

Of course. I don't think that is very controversial.

Quoting 777Jet (Reply 159):
If the crew's backup oxygen bottle exploded, what would have allowed them to have enough oxygen to remain alive until some point around the time of the final turn

Perhaps there was no fuselage hull breach and the cabin remained perfectly happily pressurized? Or there was only a small leak that delayed the onset of hypoxia? Or the crew had sufficient alternate sources of oxygen to last a while? There is no shortage of possible scenarios for having someone be able to fly the plane through all the observed maneuvers.

Quoting AIRWALK (Reply 160):
For the flight crew the oxygen is supplied by two cylinders which hold approx 3150 litres each.

These are fairly large pressure vessels and they are stored in a confined space next to all the avionics boxes. If one or both of them ruptured, the over-pressure could be sufficient to cause the cabin floor above the electronics equipment bay to suffer a structural failure. This is an area of the floor that is filled with a snake pit of wiring harnesses, in particular a number of harnesses that connect the user interface units built into the cockpit center pedestal / console to their respective computers and radios in the electronics equipment bay down below. I don't know enough about the layout of all the wire harnesses in this area to say exactly which systems would be disabled or how, but it certainly can't be discounted.

Again this is just one of multiple possibilites, and I am not wedded to it.
 
User avatar
777Jet
Topic Author
Posts: 6987
Joined: Sat Mar 08, 2014 7:29 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sat Mar 14, 2015 4:04 am

Quoting 7BOEING7 (Reply 162):
If the flight crew oxygen system failed causing a rapid depressurization, the flight crew would have between 30-60 seconds (approximately) of useful consciousness to determine their masks were inoperative and make a break for the portable bottles, several of which would be found just outside the cockpit door in the galley and by door 1L. If a pilot was able to get to a bottle and activate it (odds of that very slim) he could grab another bottle, return to the cockpit, start an emergency descent and get the other pilot on oxygen.

Thanks for that info.

As you suggest, It sounds as if the odds would be "very slim" that in those "30-60 seconds (approximately) of useful consciousness" the pilots could:

"determine their masks were inoperative"
then:
"make a break for the portable bottles"
and:
"activate it"

So, whilst it would be possible, I take it that pulling something like that off would be unlikely and probably depend on the health / fitness / alertness of the crew.

Quoting 7BOEING7 (Reply 162):
But the fact that the airplane continued on a path that indicated somebody was in control but didn't descend would indicate it wasn't a pressurization failure.

That makes sense.

I just find it hard to come up with a scenario involving a rupture of one or both of the cockpit crew backup oxygen bottles in the EE bay that would allow the plane to fly the way it did (I believe under human control / input) for about 1hr past the IGARI 'event' then to just fly on out into the middle of nowhere. I am assuming that somebody was flying the plane at the time of the final turn & SatCom re-log but then was unable to continue for whatever reason under the 'crew backup oxygen bottle in EE bay rupture / accident) scenario. I still think that MH370 was intentional and everything that was done, or not done, was because of a choice / decision made by somebody - probably the captain.

[Edited 2015-03-13 21:12:41]
DC10-10/30,MD82/88/90, 717,727,732/3/4/5/7/8/9ER,742/4,752/3,763/ER,772/E/L/3/W,788/9, 306,320,321,332/3,346,359,388
 
User avatar
777Jet
Topic Author
Posts: 6987
Joined: Sat Mar 08, 2014 7:29 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sat Mar 14, 2015 4:11 am

Quoting WingedMigrator (Reply 163):
Quoting 777Jet (Reply 159):
If the crew's backup oxygen bottle exploded, what would have allowed them to have enough oxygen to remain alive until some point around the time of the final turn

Perhaps there was no fuselage hull breach and the cabin remained perfectly happily pressurized? Or there was only a small leak that delayed the onset of hypoxia? Or the crew had sufficient alternate sources of oxygen to last a while? There is no shortage of possible scenarios for having someone be able to fly the plane through all the observed maneuvers.
Quoting WingedMigrator (Reply 163):
Perhaps there was no fuselage hull breach and the cabin remained perfectly happily pressurized?

If this was the case I would expect that the plane would still have been flown by human input past the point of the final turn / SatCom re-log on, which, IMHO, seems like the time in which human inputs might have ended leaving the plane to continue on its last heading to whereever it ended up.

Quoting WingedMigrator (Reply 163):
Or there was only a small leak that delayed the onset of hypoxia?

This is possible.

Quoting WingedMigrator (Reply 163):
Or the crew had sufficient alternate sources of oxygen to last a while?

This is also possible hence why I asked how long one of the portable oxygen bottles located in the cabin would have lasted for.

Thank you for the suggestions / ideas  
DC10-10/30,MD82/88/90, 717,727,732/3/4/5/7/8/9ER,742/4,752/3,763/ER,772/E/L/3/W,788/9, 306,320,321,332/3,346,359,388
 
User avatar
Finn350
Posts: 1601
Joined: Tue Jul 09, 2013 4:57 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sat Mar 14, 2015 4:20 am

Quoting WingedMigrator (Reply 163):
By focusing only on the user interface and what front panel knobs can be turned or what buttons can be pressed to achieve the known outcome, we may be missing half of the ways that a system can be altered or disabled. There are surely ways to make things behave differently or fail completely by disconnecting these cockpit interface units from their respective avionics boxes down below. In a complex system the front panel is just the tip of the iceberg; to consider only that is to miss the bigger picture.

Yes, and therefore the Investigation Team statement "the transponder on the occurrence flight was operating satisfactorily up to the time it was lost on the ATC radar screen at 1721.13 UTC" reveals their thinking. As I read it, there was no transponder system failure before the flight was lost on the ATC radar screen despite Mode S symbol dropped off 37 seconds earlier (Pages 6 and 40 of the Factual Information).
 
User avatar
7BOEING7
Posts: 3039
Joined: Fri Oct 12, 2012 5:28 pm

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sat Mar 14, 2015 4:28 am

Quoting WingedMigrator (Reply 163):
Perhaps there was no fuselage hull breach and the cabin remained perfectly happily pressurized? Or there was only a small leak that delayed the onset of hypoxia? Or the crew had sufficient alternate sources of oxygen to last a while? There is no shortage of possible scenarios for having someone be able to fly the plane through all the observed maneuvers.

So why didn't they descend and look for a place to land -- the plane was apparently controllable in the lateral axis, why not the vertical?
 
WingedMigrator
Posts: 1771
Joined: Wed Oct 26, 2005 9:45 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sat Mar 14, 2015 5:14 am

Quoting 7BOEING7 (Reply 167):
So why didn't they descend and look for a place to land

What makes you say they didn't look for a place to land ASAP? The plane is known to have turned towards Kota Bharu and Penang, both of which have runways suitable for an emergency landing.

As for an immediate descent, we know from the interim report that the altitude fluctuated but such descent did not occur. Who knows, maybe it would be difficult to descend in an aircraft crippled by a cylinder exploding inside the EE bay... it's possible that it wouldn't fly like a normal 777 anymore. Were the cockpit throttle levers still connected to the flight computers? Were the flight computers still connected to the engine FADECs? Would an immediate descent over the Gulf of Thailand be the fastest and safest way to get the airplane back on the ground? I have no idea.
 
mandala499
Posts: 6600
Joined: Wed Aug 29, 2001 8:47 pm

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sat Mar 14, 2015 5:23 am

Quoting Finn350 (Reply 150):
The timeline of the events is:

1720.31 UTC MH370 over waypoint IGARI
1720.36 UTC MH370 Mode S symbol dropped off
1721.13 UTC The radar position of MH370 dropped off 3.2 Nm after passing IGARI

If it the selector was put in STANDBY at 1720.36, how on earth could the transponder be detected 37 seconds later around 3 Nm off the last position?

It looks like the selector was put in ALT RPTG OFF at 1720.36 UTC and STANDBY at 1721.13 UTC.

In ALT RPTG OFF, Mode S is still active and transmitted... I wrote about this in part 75:

Quoting mandala499 (Reply 233):
If you select ALT RPTG OFF, Mode S is still active and transmitted, albeit with no ALT Data.
All those months ago, I think I asked for this information on how many seconds it took from full mode S to no secondary signal.
Yes if you want to go dark, just go to STDBY... going to ALT RPTG OFF for a while may actually raise alarms. If someone manipulated that selector, it may not have been the crew. Someone not familiar with the panel may switch to "OFF" while it's actually ALT RPTG OFF... and that off is the STDBY position.
Quoting tailskid (Reply 156):
It looks like you're right, however above some of the posters were discussing this as if it was possible to turn off mode S and leave the transponder on.

You cannot.
- STBY : Not transmitting/responding to any SSR beams.
- ALT RPTG OFF : Mode A and S
- XPNDR : Mode A, C, S
- TA ONLY: Mode A, C, S
- TA/RA : Mode A, C, S
I'll dig the manuals later...

Quoting tailskid (Reply 158):
I apologize for the confusion. I started today at post 148 and missed the context.

It happens... We've all had those days...  
When losing situational awareness, pray Cumulus Granitus isn't nearby !
 
User avatar
Finn350
Posts: 1601
Joined: Tue Jul 09, 2013 4:57 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sat Mar 14, 2015 5:45 am

Quoting mandala499 (Reply 169):
In ALT RPTG OFF, Mode S is still active and transmitted... I wrote about this in part 75:

OK, thanks for that info. Mode S symbol being dropped off on the ATC radar screen means that the altitude data was not being transmitted any more for 37 seconds. The conculusion is still the same, the transponder switch in ALT RPTG OFF position and the transponder "operating satisfactorily" ie. without failures as I read it.
 
NAV30
Posts: 1080
Joined: Sat Mar 15, 2014 9:16 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sat Mar 14, 2015 6:06 am

I'll try to keep this short - but. googling around, I found a curious thing. I can't post a link, because it produces a google reference that's about a yard long - but if people google 'MH370 track,' as I did, they'll find a plan showing MH370 flying north-east in blue..........and then turning west, in red. The red path shows an odd 'kink' in the track, well to the west, and the aeroplane then apparently turning a bit to the north-west.

Thing is, the earlier track is in blue - the western one is in red. As far as I know the official' explanation for that is that the blue path came from civilian radar - but that that radar 'lost contact,' and the later red track was established by military radar.

The 'red track' shows a curious 'kink' during which the aeroplane apparently turned north-east for a while, .but then reverted to a north-west track.

Putting it all together, it seems to me to be very possible that MH370 crashed early on, at the end of the 'blue track.' And that the authorities, through relying on the later 'military' track (from a different aeroplane), are just plain looking in the wrong place? In which case, if that's what has been happening, it's not surprising that they haven't found anything?

[Edited 2015-03-13 23:14:05]
 
User avatar
pvjin
Posts: 3586
Joined: Fri Mar 16, 2012 4:52 pm

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sat Mar 14, 2015 6:13 am

Quoting NAV30 (Reply 171):
I'll try to keep this post short - but. putting it all together, it seems to me to be very possible that MH370 crashed early on, at the end of the 'blue track.' And that the authorities, through relying on the later 'military' track, are just plain looking in the wrong place? In which case, if that's what has been happening, it's not surprising that they haven't found anything?

And you think nobody would have found anything although the end of the blue track is located in an area that sees a lot of marine traffic?

Also, the authorities did search the area and found nothing. Pings received from the aircraft prove it was flying for hours after it disappeared from the radar, unless it spent the whole time circling there's no way it could have ended up anywhere near end of that line.

[Edited 2015-03-13 23:14:16]
"Darkness cannot drive out darkness; only light can do that. Hate cannot drive out hate; only love can do that." - Martin Luther King Jr
 
User avatar
Finn350
Posts: 1601
Joined: Tue Jul 09, 2013 4:57 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sat Mar 14, 2015 6:15 am

Quoting NAV30 (Reply 171):
I'll try to keep this post short - but. putting it all together, it seems to me to be very possible that MH370 crashed early on, at the end of the 'blue track.'

I remember you suggesting this a couple of dozen times. It depends on how you define "very possible". If your definition of "very possible" is "not excluded by laws of physics as currently understood", then yes, your scenario is "very possible".

[Edited 2015-03-13 23:21:38]
 
mandala499
Posts: 6600
Joined: Wed Aug 29, 2001 8:47 pm

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sat Mar 14, 2015 7:35 am

Quoting Finn350 (Reply 170):
. The conculusion is still the same, the transponder switch in ALT RPTG OFF position and the transponder "operating satisfactorily" ie. without failures as I read it.

In ALT RPTG OFF the aircraft would still be in mode A (no altitude) and Mode S (but mode S without the altitude).
On the transponder control panel, there is no way to switch off the Mode S except by going to STDBY.

[Edited 2015-03-14 00:38:24]
When losing situational awareness, pray Cumulus Granitus isn't nearby !
 
User avatar
Finn350
Posts: 1601
Joined: Tue Jul 09, 2013 4:57 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sat Mar 14, 2015 8:00 am

Quoting mandala499 (Reply 174):
In ALT RPTG OFF the aircraft would still be in mode A (no altitude) and Mode S (but mode S without the altitude).
On the transponder control panel, there is no way to switch off the Mode S except by going to STDBY.

Yes, I understand that. According to the Factual Information, p. 6 and p. 40:

1720.36 UTC MH370 Mode S symbol dropped off
1721.13 UTC The radar position of MH370 dropped off 3.2 Nm after passing IGARI

Isn't this compatible with the selector being switched to ALT RPTG OFF at 1720.36 UTC and STANDBY at 1721.13 UTC (i.e. without altitude information, Mode S symbol is dropped off on the ATC radar screen)?

Edit: And to further clarify, the report doesn't claim that the transponder stopped responding to Mode S queries during the 37 seconds (it actually states the opposite by saying that "the transponder on the occurrence flight was operating satisfactorily up to the time it was lost on the ATC radar screen at 1721.13 UTC" on page 40).

[Edited 2015-03-14 01:18:32]
 
Kaiarahi
Posts: 1810
Joined: Tue Jul 07, 2009 6:55 pm

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sat Mar 14, 2015 11:44 am

Quoting mandala499 (Reply 174):
In ALT RPTG OFF the aircraft would still be in mode A (no altitude) and Mode S (but mode S without the altitude).
On the transponder control panel, there is no way to switch off the Mode S except by going to STDBY.

Understood, but what would cause "1720:36 UTC Mode S symbol dropped off" (presumably dropped off ATC screens)?
Empty vessels make the most noise.
 
mandala499
Posts: 6600
Joined: Wed Aug 29, 2001 8:47 pm

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sat Mar 14, 2015 3:38 pm

Quoting Finn350 (Reply 175):
Yes, I understand that. According to the Factual Information, p. 6 and p. 40:

1720.36 UTC MH370 Mode S symbol dropped off
1721.13 UTC The radar position of MH370 dropped off 3.2 Nm after passing IGARI

Isn't this compatible with the selector being switched to ALT RPTG OFF at 1720.36 UTC and STANDBY at 1721.13 UTC (i.e. without altitude information, Mode S symbol is dropped off on the ATC radar screen)?

Edit: And to further clarify, the report doesn't claim that the transponder stopped responding to Mode S queries during the 37 seconds (it actually states the opposite by saying that "the transponder on the occurrence flight was operating satisfactorily up to the time it was lost on the ATC radar screen at 1721.13 UTC" on page 40).

I see the problem...
On Page 2 it says:
The Mode S symbol of MH370 dropped off from radar display at 1720:36 UTC (0120:36 MYT), and the last secondary radar position symbol of MH370 was recorded at 1721:13 UTC (0121:13 MYT).

Whole on page 40 is stated as what you mentioned above.
I would go with the explanation on page 2 as it mentions the drop of Mode S (the screen would then refer to secondary returns), but was not clear in mentioning whether for the 37 seconds it detected mode A only or mode C. Page 40 seems to hint that it continued operating in mode C as it used "lost on ATC radar screen" as the end point. Had it been operating in mode A only, it should have been mentioned.

On a personal note, am quite peeved off with the wording used on pages 2 and 40 as it can be misunderstood...

If it transitted in Mode A and S, then we can suspect that someone switched the transponder to "ALT RPTG OFF" or that the aircraft had lost altitude input from ADIRUs to the transponder. If it went to mode A and C, then we can suspect it was a mode S failure (cannot be done by "ALT RPTG OFF"). If it was to Mode A only (no C and no A), then we're left with only us scratching our heads as it means mode C fail (or loss of altitude data) and loss of mode S.

Switching to "ALT RPTG OFF", the ATC should still see the mode S symbology on their screens but without mode C.
When losing situational awareness, pray Cumulus Granitus isn't nearby !
 
Kaiarahi
Posts: 1810
Joined: Tue Jul 07, 2009 6:55 pm

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sat Mar 14, 2015 4:37 pm

Quoting mandala499 (Reply 177):

Loss of ADIRU alt data "could" be consistent with the subsequent altitude wandering.
Empty vessels make the most noise.
 
bradmovie
Posts: 71
Joined: Tue Jan 08, 2013 11:00 pm

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sat Mar 14, 2015 9:48 pm

In following these threads, I came up with the following percentages:

Deliberate human intervention = 50%

Accident/failure/non-human caused = 50%

We really don't know...yet
 
User avatar
flyingturtle
Posts: 6054
Joined: Mon Oct 31, 2011 1:39 pm

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sun Mar 15, 2015 12:48 am

Is it already known if there was a dead-heading pilot among the passengers?

But we can probably rule out pilot incapacitation, while the passengers and F/As were still conscious and capable of acting, and if there was a pilot among the 200+ passengers.

My guess is a crazy event that took out all crew (as well as dead-heading pilots), and if that is the case... every passenger.

As far as I can remember older a.nut postings, a Qantas flight dispatched once with the crew oxygen bottles filled with nitrogen. A depressurization event together with N2 in the bottles could explain at least some parts of this disaster. In spite of being plausible, the chances of such a thing happening are... unreal.


David
Reading accident reports is what calms me down
 
tailskid
Posts: 844
Joined: Fri Jun 06, 2014 7:27 pm

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sun Mar 15, 2015 4:00 am

Quoting flyingturtle (Reply 180):
My guess is a crazy event that took out all crew

Event or events? What kind of single event could cause a 165° turnaround and loss of all comms --> then a flight to and across the Malay peninsula bringing the plane south of Pinang ---> where a 60° or so turn northward was made, then skirting but avoiding the Indonesian FIS to a point past MEKAR where a 45° or so turn was made towards the west, then passing the northern tip of Sumatera where another turn of about 90° was made putting the plane on a heading of almost due south for the next four and a half hours where it ran out of fuel?
 
User avatar
Finn350
Posts: 1601
Joined: Tue Jul 09, 2013 4:57 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sun Mar 15, 2015 5:20 am

Quoting mandala499 (Reply 177):
If it transitted in Mode A and S, then we can suspect that someone switched the transponder to "ALT RPTG OFF" or that the aircraft had lost altitude input from ADIRUs to the transponder. If it went to mode A and C, then we can suspect it was a mode S failure (cannot be done by "ALT RPTG OFF"). If it was to Mode A only (no C and no A), then we're left with only us scratching our heads as it means mode C fail (or loss of altitude data) and loss of mode S.

Let's put it this way: if the transponder signals during the last 37 seconds before it dropped off ATC radar screens could be explained only by a technical malfunction, it would pinpoint to a technical cause for the whole chain of events. As the Factual Information doesn't state anything like that and on the contrary states that the transponder was "operating satisfactorily up to the time it was lost on the ATC radar screen", we have to assume that the transponder signals are consistent with deliberate action (i.e deliberately switching to ALT RPTG OFF or something similar).
 
mandala499
Posts: 6600
Joined: Wed Aug 29, 2001 8:47 pm

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sun Mar 15, 2015 7:20 am

Quoting Kaiarahi (Reply 178):
Loss of ADIRU alt data "could" be consistent with the subsequent altitude wandering.

Agree.

Quoting Finn350 (Reply 182):
(i.e deliberately switching to ALT RPTG OFF or something similar).

Page 2 would be inconsistent with this.

http://i59.tinypic.com/2cy194l.jpg

ALT RPTG OFF will render the transponder to work in mode A and S. Page 2 states that it was the Mode S that dropped off.

When a ground station or a TCAS computer from another airplane interrogates the ATC/Mode S transponder system, the transponder transmits a pulse-coded reply signal. The reply signal identifies, and shows the altitude of the airplane. While the transponder responds to air traffic control radar beacon system (ATCRBS) mode A and mode C interrogations, the transponder also responds to the TCAS computer or ground station interrogator signal with the mode select (mode S) format. This enables the ATC to detect if it receives a Mode S response or a standard SSR response to the interrogator beam, this is given as a symbol on the ATC screen (when ATC is Mode S capable)

So, operating satisfactorily up to the time it was lost on the ATC radar screen referring to mode A & C SSR response from the aircraft, despite the Mode S dropping off, would be correct, especially if Mode S isn't mandatory in Malaysia.

I haven't found anything in the 777 FCOM yet that enables Mode S to be dropped without putting the whole transponder on standby... ALT RPTG OFF
When losing situational awareness, pray Cumulus Granitus isn't nearby !
 
User avatar
Finn350
Posts: 1601
Joined: Tue Jul 09, 2013 4:57 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sun Mar 15, 2015 7:27 am

Quoting mandala499 (Reply 183):
ALT RPTG OFF will render the transponder to work in mode A and S. Page 2 states that it was the Mode S that dropped off.

Page 2 states that Mode S symbol dropped off. We don't know why they are referring to "Mode S symbol" instead of "Mode S" and if it means that "Mode S" dropped off. Regardless, if transponder signals are consistent only with a technical malfunction (i.e. something that cannot achieved by manipulating switches etc.), I am sure they would have mentioned this in the Factual Information.

Edit: And if is the ATC radar screen that drops off Mode S symbol when altitude information is missing, it neatly explains the inconsistency.

[Edited 2015-03-15 00:36:20]
 
mandala499
Posts: 6600
Joined: Wed Aug 29, 2001 8:47 pm

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sun Mar 15, 2015 7:49 am

Quoting Finn350 (Reply 184):
I am sure they would have mentioned this in the Factual Information.

The way I read it is clear but not enough. Page 2 stated Mode S symbol dropped off and the target continued to appear under non-Mode S SSR... it then disappeared altogether (which means transponder was not transmitting/responding). BUT, I do wish they explained if in the 37 seconds they mentioned if they received the Mode C from the aircraft, instead of just using the word "satisfactorily".

Quoting Finn350 (Reply 184):
We don't know why they are referring to "Mode S symbol" instead of "Mode S" and if it means that "Mode S" dropped off.

When I look at:
The Mode S symbol of MH370 dropped off from radar display at 1720:36 UTC (0120:36 MYT), and the last secondary radar position symbol of MH370 was recorded at 1721:13 UTC (0121:13 MYT).
The disappearance of the radar position symbol of MH370 was captured by the KL ATCC radar at time 1721:13 UTC (0121:13 MYT).

What I get is:
At 1720-36, ATC stopped receiving Mode S response from the aircraft (hence the drop of the Mode S Symbol).
At 1721-13, ATC stopped receiving any response from the aircraft (no mode A, C or mode S).
I understand this as:
Before 1720-36, transponder response were mode A, (and C), S
Between 1720-36 and 1721-13, the transpnder response were more A (and C).
After 1721-13, no response.

Even if between 1720-36 someone simply put the transponder into "ALT RPTG OFF", the mode S symbol should not drop off, and the target continue to be identified as having Mode S, but no Altitude information.

Quoting Finn350 (Reply 184):
Edit: And if is the ATC radar screen that drops off Mode S symbol when altitude information is missing, it neatly explains the inconsistency.

"ALT RPTG OFF" will still result in the Mode S symbol for the target on the ATC radar screen.
If Mode S symbol and altitude information disappears at the same time, then we have a different problem, not "ALT RPTG OFF".
When losing situational awareness, pray Cumulus Granitus isn't nearby !
 
tailskid
Posts: 844
Joined: Fri Jun 06, 2014 7:27 pm

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sun Mar 15, 2015 8:04 am

This sounds to me as if the person who wrote the report misstated what he was trying to say.

I'm guessing here because I've never seen an ATC screen displaying mode S information. But It seems to me that if the ATC controller wants to see mode S info, he would have to query the AC, and the data may display on a separate screen. I believe this because there is too much data associated with mode S; if it was always displayed, the screen would be overrun with clutter.

What I think happened is that the altitude reporting stopped and the guy writing the report described it as mode S.

I also base this theory on the apparent fact that while there is no way to stop mode S reporting, there is ALT RPT OFF function.

How does this sound to you guys who know more about modern ATC than I?
 
YoungMans
Posts: 432
Joined: Sat Mar 15, 2014 10:31 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sun Mar 15, 2015 8:05 am

Quoting 777Jet (Reply 159):
And, just to clarify, do you still entertain the idea that MH370 was vaporized by some kind of nuclear device / lazer that would leave no trace of the aircraft behind when you say "shot down"???

You put me in a bit of a spot there ...
If I do reply to your question, I’ll be ridiculed and ostracised.
If I don’t reply, the same might still happen.
I have also learned, by first-hand experience, that things are brought up ages later and are then quoted or mentioned completely out of context.
With that in mind and hoping that this will now clear it up once and for all, I will reply to your triple question mark.

Let’s first define ‘shot down’. If that is meant to be by conventional means, then the answer is ‘highly unlikely’; in other words, no, it wasn’t. As it has been pointed out here many times, there would have been tell-tale debris and none, absolutely none was found.

If you are asking me whether the aircraft was shot down, as in ‘vaporising’, then the answer is not nearly so clear or straight forward. There could be a very high wall of secrecy where we have no way of knowing what new kind of weaponry might be behind it. Is it possible? Maybe yes, maybe no; I wouldn’t know because, like the rest of the public, I would have no real information on which to even form a believe.

But, ages ago I mentioned another form of shoot-down and, I feel, in that one-off case it was a reasonable contribution for the specific discussion at that time. Directed energy weapons (DEW) ....
For a site that seems to be reasonable, and well in front on Google anyway, there is a URL below.
Although, DEW's always seems to imply laser weapons; maybe they can use different forms of energy now.

And this is where it gets difficult to clearly discuss these things on A.net.
On the one hand, as I said, I don’t want to be ridiculed or ostracised ...
On the other hand, I want to discuss clearly what I actually mean.
The difficulty is, here on A.net there are generally only the professionals from the aviation industry or people who are seriously interested in that field. None of those are even inclined to deal with that type of fairy-tale topic, as they see it, not even consider it; I understand that. It smacks too much of conspiracy theories and that, as a rule, is anathema.
I’ll give it a go anyway ....

The result from a DEW may be dustification, not vaporisation.
I believe the word dustification was invented in response to what we have seen with 9/11.
Is it possible that an aircraft can be shot down and all that’s left is simply a cloud of dust?

At the time when I made the comments, I read an article somewhere, in which it was discussed that MH370 was shot down as a display of very-high-tech weaponry to a high-end military conference.
Could that have been some form of a DEW?
(Please don’t shoot me the messenger!)
I thought about this and came to the conclusion that, ultimately ...
a) I wouldn’t know because I couldn’t possibly know this; but ...
b) considering the general public is not in the ‘need-to know-circles’, in some far-fetched way it might be possible.
c) If that is what did happen, then it would have to leave virtually no debris. Dustification would do that.
d) And there was the sighting from the bloke on the oil rig.

However far-fetched even the thought might be, there were at least some indicators for consideration.

Would such weapons exist? I wouldn’t have the faintest idea!
Was such a weapon used in this case? I seem to remember that there was talk, in the early threads, of aerial manoeuvres (jet fighters) in the general area by various air forces.
From what I remember, those aerial manoeuvres were mentioned here but not resolved.

And, yes, 777Jet, if by a chance of 0.000001% something like this did happen, then it certainly would have meant that the satellite data was spoofed – for starters.


http://www.ausairpower.net/dew-ebomb.html

Also look up Wikipedia on the topic.

[Edited 2015-03-15 01:12:48]
 
User avatar
Finn350
Posts: 1601
Joined: Tue Jul 09, 2013 4:57 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sun Mar 15, 2015 8:11 am

Quoting mandala499 (Reply 186):
Even if between 1720-36 someone simply put the transponder into "ALT RPTG OFF", the mode S symbol should not drop off, and the target continue to be identified as having Mode S, but no Altitude information.

If it is not ALT RPTG OFF, then there has to be some other way to cause the Mode S symbol to drop off the ATC radar screen, if we assume a deliberate action scenario. If there is no way to do that (i.e. only a technical malfunction possible), I am sure they would have mentioned this in the report. And in a technical malfunction scenario it would be strange to state that the transponder was operating satisfactorily.
 
User avatar
Finn350
Posts: 1601
Joined: Tue Jul 09, 2013 4:57 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sun Mar 15, 2015 8:32 am

Quoting mandala499 (Reply 183):
Page 2 would be inconsistent with this.

What is your source for the transponder selector switch positions?

This manual states that ALT RPTG OFF disables Mode S, but it also additionally has a "Mode S On" selector which is not present in the images we have seen from 777 cockpits (and which is functionally identical to the XPNDR selection).



Source: http://uaecis.com/files/T2CAS/T2CAS%20Pilots%20Guide%20Rev4.pdf (3-3, p. 45/258)

[Edited 2015-03-15 01:32:42]

[Edited 2015-03-15 01:55:58]
 
User avatar
777Jet
Topic Author
Posts: 6987
Joined: Sat Mar 08, 2014 7:29 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sun Mar 15, 2015 9:03 am

Quoting pvjin (Reply 172):
Quoting NAV30 (Reply 171):
I'll try to keep this post short - but. putting it all together, it seems to me to be very possible that MH370 crashed early on, at the end of the 'blue track.' And that the authorities, through relying on the later 'military' track, are just plain looking in the wrong place? In which case, if that's what has been happening, it's not surprising that they haven't found anything?

And you think nobody would have found anything although the end of the blue track is located in an area that sees a lot of marine traffic?

Also, the authorities did search the area and found nothing. Pings received from the aircraft prove it was flying for hours after it disappeared from the radar, unless it spent the whole time circling there's no way it could have ended up anywhere near end of that line.

  

Unless MH370 flew around in circles then the handshakes / pings that continued for another six or so hours most likely indicates that the plane is a very, very long way away from the area NAV30 is suggesting.

Quoting Finn350 (Reply 173):
Quoting NAV30 (Reply 171):
I'll try to keep this post short - but. putting it all together, it seems to me to be very possible that MH370 crashed early on, at the end of the 'blue track.'

I remember you suggesting this a couple of dozen times.

NAV30 did suggest, many times, that MH370 might have gone down "then and there" - straight into the drink near IGARI. This new location proposed by NAV30 could be seen as a development in NAV30's scenario  
Quoting YoungMans (Reply 188):
Quoting 777Jet (Reply 159):
And, just to clarify, do you still entertain the idea that MH370 was vaporized by some kind of nuclear device / lazer that would leave no trace of the aircraft behind when you say "shot down"???

You put me in a bit of a spot there ...
If I do reply to your question, I’ll be ridiculed and ostracised.
If I don’t reply, the same might still happen.
I have also learned, by first-hand experience, that things are brought up ages later and are then quoted or mentioned completely out of context.
With that in mind and hoping that this will now clear it up once and for all, I will reply to your triple question mark.

My apologies - I did not mean to put you in a 'bit of a spot'.

I remember you discussed that idea in one of the earlier threads, and since you mentioned 'shot down' again in this thread, I was just curious if you still consider that scenario as a possibility?

Since that scenario was not mentioned specifically in your odds list, I take it you would include it among others in the following category:

Quoting YoungMans (Reply 122):
10 % - Unknown, weird or totally unexpected causes. This could possibly involve satellite spoofing.

I am just wondering what odds you would give that scenario if you still consider it one of the possibilities in your opinion?

That's all.

777Jet
DC10-10/30,MD82/88/90, 717,727,732/3/4/5/7/8/9ER,742/4,752/3,763/ER,772/E/L/3/W,788/9, 306,320,321,332/3,346,359,388
 
mandala499
Posts: 6600
Joined: Wed Aug 29, 2001 8:47 pm

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sun Mar 15, 2015 9:57 am

Quoting tailskid (Reply 187):
I'm guessing here because I've never seen an ATC screen displaying mode S information.

ATC screens (depending on the system) can provide targets with a symbol of "Mode S detected/available"... And yes, displaying all of the Mode S information on all aircraft with mode S is just going to clog the screen up!

So the radar sweep will do the standard Mode A & C interrogation, then also by a Mode S interrogation (to see if Mode S is available or not)... But usually ATC radar systems with Mode S will not continuously interrogate for Mode S availability on every sweep, and it will only interrogate those who had not previously responded to a Mode S availability interrogation. We don't know how often it will recheck each aircraft for Mode S availability...

Quoting Finn350 (Reply 190):
What is your source for the transponder selector switch positions?

Boeing 777-200ER FCOM... The other manual for the aircraft state the same thing...
The manual you quoted is not airplane specific. Last year I had aircraft whose transponders were simply "ON/OFF", where ON is Mode A, C, S (which caused a pilot to forgot to select the mode correctly on another tailnumber (the only one in the fleet with just Mode A, C), and I had to receive a call from the ATC complaining after the aircraft flew in mode A only causing others to get TCAS warnings... *ooops*    )...

Anyway back to the 777-200ER... here are some more from the manual:


Note that if you lose altitude information from the ADIRU, the altitude source can be switched to the SAARU aswell... which brings me to...

Quoting Kaiarahi (Reply 178):
Loss of ADIRU alt data "could" be consistent with the subsequent altitude wandering.

The question is, why can't they use the SAARU?
*headaches*

Quoting Finn350 (Reply 189):
If it is not ALT RPTG OFF, then there has to be some other way to cause the Mode S symbol to drop off the ATC radar screen, if we assume a deliberate action scenario. If there is no way to do that (i.e. only a technical malfunction possible), I am sure they would have mentioned this in the report.

I hear you... digging the manuals to see what could it be. Even going into the E&E bay, I still find it difficult to get something that would result in the "same thing", even with bringing a crash axe or a flamethrower into the E&E bay...
If you got another idea on how this could be done by deliberate action, I'd look it up on the manuals to see if it's possible.

One thing though (see the reply to tailskid on the top of this reply), we don't know how often the radar will interrogate an airplane already known in the session to have Mode S if the mode is stil available or not... So the mode S may have dropped off earlier(?)...

Now... I must warn everyone on being careful about the transponder... The page for the transponder in the manuals I have is dated June 2008... now, the latest MH Boeing 777 we have in a.net database is from the same month...
and... look at the transponder panel:

View Large View Medium
Click here for bigger photo!

Photo © TK


There maybe differences to the default 777 set up with regards to Mode S...
When losing situational awareness, pray Cumulus Granitus isn't nearby !
 
YoungMans
Posts: 432
Joined: Sat Mar 15, 2014 10:31 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sun Mar 15, 2015 10:12 am

Quoting 777Jet (Reply 191):
I am just wondering what odds you would give that scenario if you still consider it one of the possibilities in your opinion?

The odds-on for something I've described is of course far, far less than the 'Captain did it'. It would rate only with your proverbial 0.001% chance. In other words, whilst it is highly unlikely, it still has to stay on the books of weirdest possibilities because nothing can be ruled out just yet. At least not until we have much more information or, better still, actual evidence.

But yes, it would fall under the "10 % - Unknown, weird or totally unexpected causes." Although, it would only be a mere fraction of a possibility.

And now that you are pressing me, even the 10% for that category seems to be somewhat high.
Then again, should it be 1% or 5% or even ten; who knows.
What is important here is, that we may be dealing with possible events or occurrences for which there is simply no precedent.

I'm not sure if this has been mentioned but I reckon that MH370 is setting a precedent in its own right.
 
User avatar
Finn350
Posts: 1601
Joined: Tue Jul 09, 2013 4:57 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sun Mar 15, 2015 10:42 am

Quoting mandala499 (Reply 192):
Now... I must warn everyone on being careful about the transponder... The page for the transponder in the manuals I have is dated June 2008... now, the latest MH Boeing 777 we have in a.net database is from the same month...
and... look at the transponder panel:

Here is a link to the Pilot's manual of the transponder that was installed on MH370 (Bendix/King TRA-67A Mode S transponder, Factual Information, page 39):

http://www.bendixking.com/HWL/media/Pilot-Guides/006-18201-0000_3.pdf

For example, page 54:

ALT OFF activates the selected transponder without altitude reporting. TCAS is in standby. on is annunciated in the display window.
XPDR activates Mode S transponder with altitude reporting, tCaS system in standby.

The wording is unclear, but it could be interpreted that Mode S is not activated in ALT OFF. Possibly actual transponder configuration affects which modes are active in "ALT OFF" selector switch position.
 
ltbewr
Posts: 15591
Joined: Thu Jan 29, 2004 1:24 pm

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sun Mar 15, 2015 10:49 am

The theory of some massive failure of or an intentional act of shutting down the pressurization and/or emergency O2 systems in the cockpit and/or cabin is intriguing. Depressurization seems to possible based on 2 other well documented cases, Helios and as to pro golfer Payne Stewart where both aircraft pretty much continued on a final set path and crashing when they ran out of fuel. With Helios, we believe the pilots made an error in the settings for the pressurization and emergency O2 systems, with Payne Stewart it was likely some sudden mechanical failure.
The scenario of an 'exploding' O2 tank taking out the avionics would be one way to move the blame away from the pilot and indeed would likely make them look better, and perhaps heroic, as they did try to turn around, to return to 'home' airport but passed out shortly after the last turn. Of course this has its own issues. If a mechanical failure of the pressurization system occurred, the pilots failed to take the most important act of all, that is drop altitude to 10,000 ft or less. If there had be an explosion, the aircraft could or should have had major external damage that likely would have shortened its range and crash sooner.
This leads back to 'the pilot did it' or 'terrorists did it' scenarios, both with their own issues that have been well discussed in 1000's of posts.
 
mandala499
Posts: 6600
Joined: Wed Aug 29, 2001 8:47 pm

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sun Mar 15, 2015 1:09 pm

Quoting Finn350 (Reply 194):
Here is a link to the Pilot's manual of the transponder that was installed on MH370 (Bendix/King TRA-67A Mode S transponder, Factual Information, page 39):

We have a problem...
1. The manual you quoted is a "Pilot's Guide", not a manual.
2. For use in the aircraft, on the page after the cover it says the following: The information contained in this manual is for reference use only. If any information contained herein conflicts with similar information contained in the Airplane Flight Manual Supplement, the information in the Airplane Flight Manual Supplement shall take precedence
3. On Page 40 in that Pilot's Guide (Using CTA 81A/D controls, the most similar to the 777 in my opinion) it says: ALT OFF: ALT OFF activates Mode S transponder without altitude reporting, TCAS system in standby. (And the lack of range rings on MH's photo can be explained by page 49: the TCAS RANGE Selector is used to select the range on the traffic display. the range is in nautical miles. (Note: This feature may be superceded by a range control on the traffic display bezel in some installations.) (which in this case, the range is in the Nav Display Settings and not on the transponder control panel).

However, I do agree to the following:

Quoting Finn350 (Reply 194):
The wording is unclear, but it could be interpreted that Mode S is not activated in ALT OFF. Possibly actual transponder configuration affects which modes are active in "ALT OFF" selector switch position.

It is unclear and frustrating, regardless of whether one believes ALT RPTG OFF has the mode S or not... Personally, I think a Mode S transponder will always have the mode S available, with or without the Altitude input, but the TCAS would be buggered without the altitude input.
When losing situational awareness, pray Cumulus Granitus isn't nearby !
 
User avatar
Finn350
Posts: 1601
Joined: Tue Jul 09, 2013 4:57 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sun Mar 15, 2015 5:11 pm

Quoting mandala499 (Reply 196):

It is unclear and frustrating, regardless of whether one believes ALT RPTG OFF has the mode S or not... Personally, I think a Mode S transponder will always have the mode S available, with or without the Altitude input, but the TCAS would be buggered without the altitude input.

OK, here is a link to an installation manual to Honeywell MST 67A, which if not the same very similar to Bendix/King TRA-67A.

Quote:
In-Flight - Turns on Mode S transponder to fully active state and places TCAS in STANDBY mode (TCAS sensitivity level #1). Mode S transponder transmits squitters and replies to Mode S and ATCRBS Mode C and Mode A interrogations. The Mode S transponder’s reply to Mode C and Mode S interrogations does not contain an altitude report. The transponder’s reply to Mode A interrogations contains the ATC transponder code (normal Mode A reply). All TCAS broadcasts, surveillance, and tracking functions are disabled. Traffic display screen is blanked except for a TCAS STBY mode annunciation.

Source: http://www.neboservice.ru/docs/0216544001186664708.pdf (page 55)

It appears to confirm that when in "ALT OFF" position the transponder will reply to Mode S queries. So there has to be another reason for Mode S symbol dropping off the ATC radar screen.
 
mandala499
Posts: 6600
Joined: Wed Aug 29, 2001 8:47 pm

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sun Mar 15, 2015 5:32 pm

Quoting Finn350 (Reply 197):
OK, here is a link to an installation manual to Honeywell MST 67A, which if not the same very similar to Bendix/King TRA-67A.

Nice find!   Yes, it is the same, with the CTA 81A / D control panel (and it has the option of not having the range selector on the TCAS panel, shown).

Quoting Finn350 (Reply 197):
So there has to be another reason for Mode S symbol dropping off the ATC radar screen.

Been stuck with this since the report came out... *frustrated*
When losing situational awareness, pray Cumulus Granitus isn't nearby !
 
User avatar
AirlineCritic
Posts: 1777
Joined: Sat Mar 14, 2009 1:07 pm

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sun Mar 15, 2015 5:38 pm

Quoting Finn350 (Reply 182):
Let's put it this way: if the transponder signals during the last 37 seconds before it dropped off ATC radar screens could be explained only by a technical malfunction, it would pinpoint to a technical cause for the whole chain of events.

I have been thinking along the same lines.

Quoting Finn350 (Reply 184):
Regardless, if transponder signals are consistent only with a technical malfunction (i.e. something that cannot achieved by manipulating switches etc.), I am sure they would have mentioned this in the Factual Information.
Quoting Finn350 (Reply 189):
If it is not ALT RPTG OFF, then there has to be some other way to cause the Mode S symbol to drop off the ATC radar screen, if we assume a deliberate action scenario. If there is no way to do that (i.e. only a technical malfunction possible), I am sure they would have mentioned this in the report.

I not so sure about that. This is a preliminary report that does not attempt to make conclusions, it is a report of factual information.

Quoting Finn350 (Reply 189):
And in a technical malfunction scenario it would be strange to state that the transponder was operating satisfactorily.

That is indeed a bit strange. Although you could argue that the externally observable behaviour of transponder is still according to the specifications how they must behave on the radio; it responds. But if you take the whole situation into account, the transponder system does not behave properly, if it drops a mode without commanded to do so.

The report is unfortunately vaguely worded. I look at it this way, one of the following is true:

1) The investigators believe this is a major lead to what actually happened, basically ruling out at least simple ways of the pilot causing the observed behaviour. But since the report is about facts, they do not highlight the conclusion.

2) The observed behaviour can be explained by altitude information becoming unreliable. (Will this look like S mode is off?) Note that altitude information could become unreliable by either technical causes or through malicious action, such as turning something off from the cockpit.

3) The report is in error and the observed behaviour can be explained by someone setting the mode to STDBY.

4) There's a race condition between the ATC systems interrogating the transponder, and someone setting the mode to STDBY. For instance, other modes may have been queried, mode set to STDBY, and then the S mode query no longer goes through.
 
WingedMigrator
Posts: 1771
Joined: Wed Oct 26, 2005 9:45 am

RE: Malaysia Airlines B772 Missing KUL-PEK Part 76

Sun Mar 15, 2015 5:50 pm

Quoting LTBEWR (Reply 195):
If there had be an explosion, the aircraft could or should have had major external damage

The oxygen tank failure would not necessarily be what you might think of as an "explosion". A cylinder rupture could cause a localized over-pressure (less than one atmosphere) that would not be so great as to damage the external fuselage structure, which is designed to take very large pressurization loads. The cabin floor, on the other hand, is not designed to take pressure loads and could fail, damaging the electrical harnessing that is built into it. Turkish flight 981 demonstrated this effect with a pressure differential of just 2 psi across the floor causing a massive structural failure.

Again, the only reason that I am curious about this failure mode is that the crew O2 system was re-pressurized (for the first time in 1.5 months) just prior to the accident flight.

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos