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Finn350
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 3:32 am

Quoting nupogodi (Reply 298):
Lack of radar contact/return.

Yes, that is obvious, but I meant what is the reason for the lack of radar contact/return? The graph indicates that the aircraft was inside the of range of the Butterworth AB radar up to 200 nm.
 
SimonDanger
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 3:34 am

Quoting Starlionblue (Reply 297):
I assume that if you're down to RAT the autopilot would have disconnected and the control law degraded to a basic level. So if we're assuming incapacitated or otherwise inactive flight crew, there would be no commanded movement of control surfaces.

Makes sense...thanks. It sounds like all you guys were in class applying yourselves while I was smoking in the boys room!
 
mandala499
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 3:34 am

Quoting canoecarrier (Reply 254):
Something tells me you have built quite a spreadsheet by now friend

Actually, no, haven't started on the spreadsheet, just a bunch of notes that are bits and pieces.

Quoting 65mustang (Reply 257):
Is it a ridiculous idea to fuel up an identical 777 and send it along the suspected route to verify data?

No, but this can all be done with basic computer modelling to eliminate the unlikely, and more advanced modelling for the likely, and simulate it only if you really need to.

Quoting 65mustang (Reply 275):
Are there any protocols in place for Maylaysia airlines or atc to attempt to contact a plane via satillite phone if it goes missing? If a sat call was made and not answered would the attempt look like a ping or something else?

I don't think so. The attempt would actually trigger a spur of data exchange with the GPS coordinates in the packet headers.

Quoting GZed (Reply 278):
Rcair1, can I ask why you have elected not to include this track and waypoints in your "Sanity Check". Previous discussions here have concluded that this is MH370 tracking out of PEN to VAMPI, then a turn to MEKAR.

This is the one revealing the part that was covered by a person in the other photo:
http://tmfassociates.com/blog/wp-content/uploads/2014/03/Beijing-event.jpg

Quoting vnangia (Reply 280):
The initial area was just borderline outside of the coverage of the satellite at 178E, POR. The new area appears to be within the range of POR. Shouldn't we be able to now get a more precise fix?

The terminal would using Position data (be it from GPS on its own on the LGA, or fed from the FMC through an ARINC-429 data feed) for the Satellite Data Unit to determine which of the two satellites that it are in range to contact, steer the beam to it, and initiate a handshake, saying "I am at this location", etc etc etc.
It wouldn't talk to 2 inmarsat satellites at the same time. Even if on a satellite hand-off...

Quoting BackSeater (Reply 281):
If you read my posts in the previous threads re. radar calculations, I used the erratic returns to compute probable altitudes and climb rates for MH370 from a very, very low altitude to cruise.

Damn, where were those numbers you made again! Grrr... lost it in my notes *sigh*
When losing situational awareness, pray Cumulus Granitus isn't nearby !
 
nupogodi
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 3:37 am

Quoting Finn350 (Reply 300):
Yes, that is obvious, but I meant what is the reason for the lack of radar contact/return? The graph indicates that the aircraft was inside the of range of the Butterworth AB radar up to 200 nm.

Is there part of the terrain that would block PSR there? Perhaps they were in the radar shadow of a mountain? If there was terrain, how low would they have to be to be in that shadow for that period? These are the questions you want answered.
A man must know how to look before he can hope to see.
 
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Finn350
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 3:44 am

Quoting nupogodi (Reply 303):
Is there part of the terrain that would block PSR there? Perhaps they were in the radar shadow of a mountain? If there was terrain, how low would they have to be to be in that shadow for that period? These are the questions you want answered.

I assume that the radar plot is from a single radar at Butterworth AB. As the plane re-appeared in the radar later in almost the same direction, the most likely reason is a lower flying altitude where the plane is under radar coverage. I wonder if that was the re-pressurization of the plane (assuming that there was a de-pressurization earlier).
 
nupogodi
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 3:50 am

Quoting Finn350 (Reply 304):
I assume that the radar plot is from a single radar at Butterworth AB. As the plane re-appeared in the radar later in almost the same direction, the most likely reason is a lower flying altitude where the plane is under radar coverage. I wonder if that was the re-pressurization of the plane (assuming that there was a de-pressurization earlier).

Yeah it's true, Butterworth is pretty well lined up with MEKAR so they should have had a straight shot to them en-route.

I'm at a total loss. I can't explain it. Without knowing details about their radar we don't know what altitude they would have to be at to evade it. There would be no point to it though, if they were going to re-appear soon anyway. I have no idea.
A man must know how to look before he can hope to see.
 
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7BOEING7
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 3:52 am

Quoting SimonDanger (Reply 296):
This sounds like it answers my question. Do you suppose the generators would still be operational if the engines were wind-milling?

No, but the engine driven hydraulics work depending on the wind milling speed.

Quoting Starlionblue (Reply 297):
I assume that if you're down to RAT the autopilot would have disconnected and the control law degraded to a basic level. So if we're assuming incapacitated or otherwise inactive flight crew, there would be no commanded movement of control surfaces

Actually you're in secondary and you're envelope protection is gone, so with nobody at the helm the airplane will eventually end up out of control.
 
Backseater
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 4:03 am

Quoting nupogodi (Reply 298):
Quoting Finn350 (Reply 294):
What was the significance of the white circle in the middle? The aircraft flying at a lower altitude?
Quoting Finn350 (Reply 300):
Yes, that is obvious, but I meant what is the reason for the lack of radar contact/return? The graph indicates that the aircraft was inside the of range of the Butterworth AB radar up to 200 nm.
Quoting Finn350 (Reply 300):
Is there part of the terrain that would block PSR there? Perhaps they were in the radar shadow of a mountain? If there was terrain, how low would they have to be to be in that shadow for that period? These are the questions you want answered.
Quoting Finn350 (Reply 304):
I assume that the radar plot is from a single radar at Butterworth AB. As the plane re-appeared in the radar later in almost the same direction, the most likely reason is a lower flying altitude where the plane is under radar coverage. I wonder if that was the re-pressurization of the plane (assuming that there was a de-pressurization earlier).

Remember the earth in not flat!!!!! And radars do not do very well when the antenna is at essentially sea level and the target is at too low an altitude for a given distance from the radar antenna. West of Penang there were no obstacles that could have blocked the radar returns. So?

I have provided very plausible answers (no UFO!) to all your questions in my previous posts #112 in thread 43, #178 in 44 and #110 in 45.
 
Skydrol
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 4:20 am

Quoting nupogodi (Reply 303):
Is there part of the terrain that would block PSR there? Perhaps they were in the radar shadow of a mountain? If there was terrain, how low would they have to be to be in that shadow for that period? These are the questions you want answered.

Dude, do you even sleep? You have only joined a.net three weeks ago and already have more than 440 posts (my guess, mostly about MH370). You should be part of the investigation team!  




LD4
∙ ---{--« ∙ ----{--« ∙ --{-« ∙ ---{--« ∙ --{--« ∙ --{-« ∙ ----{--« ∙
 
nupogodi
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 5:01 am

Quoting Skydrol (Reply 308):
Dude, do you even sleep? You have only joined a.net three weeks ago and already have more than 440 posts (my guess, mostly about MH370). You should be part of the investigation team!  

I'm on vacation and even when I'm not, I work from home. Software development is awesome. Bullshit projects for moneyed clients pays for flying time.

But, uh, yeah, I did join A.net for this thread but I lurked for a long time.
A man must know how to look before he can hope to see.
 
oldas
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 6:32 am

One question: Lets assume I would like to go with T7 as far as I can. Does it make a sence to fly with only one engine or any other "assymetrical" thrust config (at most efficency balance of speed/fuel consumption) and extend the range of a/c by this?
 
mandala499
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 6:38 am

Quoting oldas (Reply 310):
One question:

No it doesn't....
1 engine out = more drag from the inoperative engine.
1 engine out = lower altitude
lower altitude = more fuel burn per engine for a given thrust.
1 engine out = slower cruise speed
Add more drag, lower altitude, more fuel burn per engine for a given thrust, and a slower cruise speed, the answer is again...
No...
When losing situational awareness, pray Cumulus Granitus isn't nearby !
 
65mustang
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 6:39 am

Quoting mandala499 (Reply 302):
I don't think so. The attempt would actually trigger a spur of data exchange with the GPS coordinates in the packet headers.

Thank you for your response. I saw this in the communications summary:

The SATCOM system provides both data and voice communications. The system is managed by the satellite data unit. Flight deck voice calls are controlled using the CDUs and audio control panels.
The SATCOM control pages are displayed by selecting SAT on the CDU menu page. Directories of airline-defined numbers are line-selectable or numbers may be manually entered if function is enabled by the operator.
Incoming SATCOM calls are annunciated by a SELCAL chime and illumination of a CALL light on the audio control panel. Pressing the respective transmitter select switch connects the call to the pilot headset/hand mic.
SATCOM calls are terminated when the CALL light extinguishes (ground party hang-up or pilot ends call).
The EICAS communication message SATCOM MESSAGE displays when a SATCOM message requires flight crew attention. Servicing the message clears the EICAS message.

It appears to me if there would have been an attempt to call the plane between when vietnames atc noticed the plane was missing and 8:18am, there would be a lot more info to help find the plane.
 
oldas
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 7:00 am

Quoting mandala499 (Reply 311):

Thanks, clear.
And second question: does FDR include all data of autopilot setting?
 
Pihero
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 7:17 am

Quoting nupogodi (Reply 269):
And if you wanted to confirm the INMARSAT data, you'd have to also begin your flight at precisely the same point in the satellite's orbit.

The NTSB / Inmarsat *loci* are totally independent from a point of origin.

Quoting rc135x (Reply 270):
Even so it certainly suggests the difficulty of the task at hand, and makes the voyage of the James Caird that more phenomenal.

... Incredible what human ingenuity can achieve .

Quoting SimonDanger (Reply 285):
it appears that there would be a very limited but guaranteed supply of electrical and hydralic power provided by the RAM until contact with the water. Would this not mean then that A: there may have been some pitch and roll adjustments on decent, and B: that the last half ping was precisely the time of water contact?[/quote
SATCOM would be among the shedded loads, certainly. On the other hand, the interruption can be due to a loss of line-sight to the satellite, i.e an excessive bank angle.

[quote=aftgaffe,reply=291]
That could be. But what would trigger an off-interval ping in the first place?

Only reason I can think of : the aircraft was attempting to transmit. But what ?

Quoting SimonDanger (Reply 296):
. Do you suppose the generators would still be operational if the engines were wind-milling?

No. The IDGs would disconnect. But you could have *some* hydraulic power left.

Quoting Starlionblue (Reply 297):
I assume that if you're down to RAT the autopilot would have disconnected and the control law degraded to a basic level. So if we're assuming incapacitated or otherwise inactive flight crew, there would be no commanded movement of control surfaces.

Yes, with a very high probability... The highest...
Contrail designer
 
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Finn350
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 7:54 am

Quoting Pihero (Reply 314):
Only reason I can think of : the aircraft was attempting to transmit. But what ?

This is a good explanation:

Quote:
The pings on the Doppler chart weren’t regularly spaced and the irregular ones appeared to coincide with the period of rapid altitude changes, after initial turn,” says Tim Farrar, an analyst with TMF Associates, a consulting firm based in Menlo Park, Calif. “That would imply the terminal on the plane potentially tried to reacquire the signal after it lost the satellite signal during a sharp maneuver. If that supposition is correct, then the last partial ping is potentially due to the same issue (dive/stall etc). Therefore one might conclude tentatively that the plane crash was at or close to that time.”

Source: http://www.aviationweek.com/Article....e-xml/awx_03_26_2014_p0-675307.xml
 
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p51tang
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 8:40 am

Quoting mouldypete (Reply 187):
From mercure1 in the last thread:

"The latest bloomberg article has the following: "The Boeing 777 was carrying 49.1 metric tons (54.1 tons) of fuel when it departed Kuala Lumpur, for a total takeoff weight of 223.5 tons, according to Subang Jaya-based Malaysian Air."

Based on my own calculations, this would give it apprx 8hrs (480min) total range for this aircrafts vintage, climbing and then flying along at M.84/485TAS @ Opt FLs.
TOW 223.5t
ZFW ~ 174.4t (payload ~25.4t)
OFF fuel 49.1t

The 777-200ER T892 will burn apprx 6.1t per hour on avg, at those wts and FLs.

VAMPI would likely be reach 82min after takeoff, via the DCT PIBOS R208 IGARI DCT VAMPI routing.
398min (6.6hrs) range from VAMPI @ 485KTAS = 3217nm . Heck thats almost to the Kerguelen Islands."

This fuel burn information Is very helpful.I've used mapping http://www.freemaptools.com/measure-distance.htm to calculate the distance in km's (as opposed to Nautical Miles) from Kuala Lumpur Malaysia across the South China Sea to where ATC handover was to have taken place.I then tracked this back to the Strait of Malacca and across to an equidistant point between Great Nicobar Island and Banda Aceh Indonesia.It does not show the way-points as I wanted to simplify the process.It gave me a total distance of 1,562 km.

Attached:



I then added that distance to the rest of the journey.This section is 4,655 km.I chose an endpoint of Diamantina Deep which is the deepest part of Diamantina Trench @ (7,000+ m).

Attached:




Adding both = 6,217 km.


And yes, I know NTSB has already done the math in a more sophisticated way.But.They have not been forthcoming in terms of disseminating distances covered, and fuel burn figures to the Media.It's just been the 400kt and 450kt arc track.

I also plotted straight-line distance from:

Kuala Lumpur to Beijing = 4,365 km
Kuala Lumpur to Diamantina Deep = 4,244 km


Almost identical.


Now I wanted to work out the 'overhead fuel load' that Airlines are required to carry as part of Civil Aviation Safety Requirements.

Quote:
- percentage of time: typically 10%, i.e. a 10-hour flight needs enough reserve to fly for another hour.
- percentage of fuel: typically 5%, i.e. a flight requiring 20,000 kg of fuel needs a reserve of 1,000 kg.
http://en.wikipedia.org/wiki/Flight_planning

Based on (percentage of fuel) 49.1 ton of Avgas at 5% would give a mandatory reserve of 2.45 ton included in the original fuel load of 49.1 ton.

As I'm not a Rocket Scientist, I need assistance with the next part:

I'd like to know what the likely fuel burn was?, using my original figure of (6,217 km) total distance covered by MH370 as outlined in my attached images.With that information, I'd also like to know how much of the mandatory fuel reserve was burnt,as there is nothing to suggest that MH370 'ran out of fuel'.

I know that by deducting the flight distance (Kuala Lumpur to Beijing) 4,365 km from the flight distance that MH370 actually ended up taking 6,217 km is approx 1,852km.

So my question is: What percentage of the fuel load is left?, as MH370 would have theoretically landed in Beijing 1,852 km before, at the lower figure.

Did you notice something also??.Why is 1,852 km the current distance that Search And Reconnaissance are now searching west from Perth?.

Attached:



I also note that Diamantina Deep is not very far from the New Search location.

Attached:



This link provides better insight into the new search location. http://upload.wikimedia.org/wikipedi...509px-Diamantinatopography.svg.png

I also provide a weather map, which provides wind direction.I chose Diamantina Deep as my reference point.It is located at 180 degrees and current wind speed is around 36 kph.I noted on this mapping that the wind has a North North West track.

http://earth.nullschool.net/#current...l/orthographic=-250.18,-28.45,1106


I trust that this meets the requirements of a high quality post,and I look forward to your feedback.Thanks in advance.  
 
NAV30
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 9:51 am

Quoting p51tang (Reply 316):
Did you notice something also??.Why is 1,852 km the current distance that Search And Reconnaissance are now searching west from Perth?.

Because sea and air navigation still work on nautical miles, p51tang. 1,852km. is 1,000 nms.

No way of changing everything to metric. It would cost a fortune, in terms of new navigational equipment, and achieve nothing.............
 
Pihero
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 9:56 am

Quoting p51tang (Reply 316):

I trust that this meets the requirements of a high quality post

It does because at least you're interested in trying to meet facts and theory together.
However :
1/- Fuel Planning
for the airborne part of the flight, these are the components :
- Trip fuel : burn-off from departure to destination ; it includes Takeoff / Climb / Cruise / Descent and Approach
- Route reserve : Generally taken as a 5 % percentage of Trip Fuel. Some further computations ( due to the fact that the more fuel one takes, the more is burned just for carrying the extra ), it can be as low as 3 % of Trip fuel.
- Alternate reserve : Consider a diversion from the destination airport, for any reason : Weather / Closure... etc... it includes froml a go-around the fuel needed to divert to a planned airport.
- Holding fuel... basically at captain's discretion. BY law it's equivalent to 15 minutes iof holding at 1500 ft, but will depend on the country's regs.
So, in your post, you haven't considered the Diversion and the holding fuel quantity.

2/- Fuel Burn-Off
It is highly dependent on Aircraft weight / Aircraft Mach / Altitude + Temperature.
On normal operations, we use a *cost index* which programs the airplane to fly at an optimum AoA, with decreasing Machs with decreasing weights ( as the airplane gets lighter nwith burned fuel, the Mach number decreases )... But yoy also have the choice of a constant Mach / a constant schedule : Long range ; Max range ; Max endurance...
What mach schedule was followed during this flight ? It's down to speculations...and neither Bpoeing or the investigators have been forthcoming with the fuel information and trip fuel graphs.
Therefore, your "Kuala Lumpur to Beijing = 4,365 km
Kuala Lumpur to Diamantina Deep = 4,244 km"

doesn't take into account any of the reserve quantities I mentioned above.

Btw, the fuel is Jet A1, not Avgas.

3/- On Wind influence
It's not negligible at all. Please see for instance the *winds aloft* charts I obtained from Tim Vasquez in an earlier post (previous thread, I guess )
My aviation / navigation hunch is that it has been as accurately as possible included in the NTSB study.

4/- On Coincidences
"actually ended up taking 6,217 km is approx 1,852km....
...Did you notice something also??.Why is 1,852 km the current distance that Search And Reconnaissance are now searching west from Perth?."

1852 km = 1000 nautical miles... It's just a ball park figure for the distance between Perth and the search area.
:
IMHO, you should refine your theory with the distance and expected burn-off from KL to the time of 08:19... it could be interesting.
At least for me.

Rgds
Contrail designer
 
monjonman
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 9:58 am

Can anyone confirm or has seen a statement or news article that indicates they have also dropped new sonar buoys at the new search location and if they are determining the surface water movements there as well.
 
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p51tang
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 10:24 am

Hi Pihero,thanks for your reply.

Quoting Pihero (Reply 318):
IMHO, you should refine your theory with the distance and expected burn-off from KL to the time of 08:19... it could be interesting.
Quoting p51tang (Reply 316):
So my question is: What percentage of the fuel load is left?, as MH370 would have theoretically landed in Beijing 1,852 km before, at the lower figure.


Are we both asking the same question?.In that,we both don't know what the fuel burn is?.
 
Pihero
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 11:57 am

Quoting p51tang (Reply 320):
,we both don't know what the fuel burn is?.

Actually, we do, with a good approximation : FOB at T/O = 49.1 tons,
so imagining ( that's not too hard ) that the flight eventually ran out of fuel, Fuel burn = 49.1 - unusable quantities in tanks, a few hundred kilograms.
BUt that's not very useful as we don't know the cruising speed, nor do we the flight level... and I personally have no access to the fuel consumption tables or graphs from the FCOM.
Further : the figures released to the press : TOW FOB etc... haven't been officially confirmed.

We'll have to wait until the publication of the first prelim report in which I expect to find:
-The loadsheet :TOW /Traffic Load / FOB / Elected Alternate / Fuel sheet etc...
- A series of endurance tables for different cruise schedules
- A description of the satellite-derived LOPs and the investigators' assumptions.

[Edited 2014-03-29 05:32:16]
Contrail designer
 
YoungMans
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 11:58 am

For whom it may concern:
Flight Data Recorders (Black Boxes) sonar-ping ... for future consideration.

Background ...
The 30-day limit in which the 'Black Boxes' must be found (after which the signal stops) puts a lot of pressure on any SAR personnel. Unless the Black Boxes are found quickly, within a matter of a few days, battery power is wasted.

Suggestion for future consideration ...
Maybe the aviation industry should look at marine science for inspiration on this.
Couldn't the Black Boxes stop transmitting their regular signals after, say, three or even five days.
The Black Boxes would then switch to a 'Listening-Mode' to conserve battery power.
They would resume transmitting signals as soon as a coded (search) signal is sent to the Black Boxes.

This kind of technology works and is in relative common use.
I have personally seen it when technicians on behalf of the Woods Hole Oceanographic Institution retrieved buoys that were anchored to the sea floor in 2,000 metres plus, for a year; in fact, in the most southern parts of the Indian Ocean.

The ship travels to the exact coordinates where the buoy was deployed and a signal is then sent to it. If the location is correct, the buoy will 'Wake Up' and answers with its coded pings. The ship may then have to relocate slightly for best reception, i.e. to be as close as possible to the correct position. When good contact is established, a signal is sent to the buoy which will then release itself off the ocean floor and drift to the surface. It then takes an hour or more (depending on the depth) before the buoy arrives on the surface. Even though the floats are still bright yellow after all that time, and at least the size of a 200 litre (44 gall) drum, it is still very hard to spot and find them in the rough water.

The take-home message is this ....
Black Boxes, when submerged, should stop transmitting after about three days, to preserve battery power.
They then enter a 'Listening-Mode'.
The Black Boxes will resume signal-transmission when contacted by a search signal.

(Yes, I know, '..the ship travels to the exact coordinates where the buoy was deployed..'. Whatever happens, though, an area has to be reasonably closely defined to search for the Black Boxes. This holds true if one only listens out for the signal [coming from the Black Boxes] or if one were to send a signal to trigger an answer.)
 
mouldypete
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 12:09 pm

One interest of note is that if the new proposed possible track is correct, then the a/c must have flown for at least 1000kms through the coverage area of the Australian JORN radar system. Makes one wonder if it was turned on?
Presumably the Australian authorities will have noted this and checked. Their silence suggests strongly that it was not operating.  
 
nupogodi
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 12:35 pm

Quoting Pihero (Reply 314):
The NTSB / Inmarsat *loci* are totally independent from a point of origin.

Sorry buddy, you're 100% incorrect this time! The original arcs assumed a stationary satellite, but the Doppler analysis specifically relied on the satellite's inclination.

And it was the AAIB that released that data, not the NTSB.

edit: What I'm saying is that therefore, if you were to replicate the same conditions with a test flight, the satellite would need to be in the exact same position in its orbit when you took off.

I know some French people don't like Quebecers, but I can assure you, I'm from Ontario  Wink There is no need to rush to correct me, I have been paying attention.

[Edited 2014-03-29 05:53:55]
A man must know how to look before he can hope to see.
 
Kaiarahi
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 12:46 pm

Quoting mouldypete (Reply 323):
then the a/c must have flown for at least 1000kms through the coverage area of the Australian JORN radar system. Makes one wonder if it was turned on?

Answered upthread. JOR2 (near Laverton, WA) is not operated continuously and the scan arc depends on military considerations - it likely spends most of its time looking north, rather than into an empty ocean. Australian authorities have declined to confirm whether or not it captured anything. One would assume that if it was operational, scanning in the right direction and anything was seen, the RAAF would not be wasting resources in the wrong place.
Empty vessels make the most noise.
 
rheinwaldner
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 12:53 pm

Quoting oldas (Reply 310):
One question: Lets assume I would like to go with T7 as far as I can.

Then I would reduce speed....
Many things are difficult, all things are possible!
 
Backseater
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 12:59 pm

Quoting nupogodi (Reply 324):
Quoting Pihero (Reply 314):
The NTSB / Inmarsat *loci* are totally independent from a point of origin.

Sorry buddy, you're 100% incorrect this time! The original arcs assumed a stationary satellite, but the Doppler analysis specifically relied on the satellite's inclination.

Pihero is right.
The locus for the Nth ping only depends on the RTD and the satellite position at that ping time. When you change the starting position, of course you might end up somewhere else but still on the same locus for that ping.

I can't even begin to imagine Inmarsat computing RTD derived loci using an inclined orbit satellite and ignoring satellite motion!!!!
 
nupogodi
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 1:04 pm

Quoting BackSeater (Reply 327):
Pihero is right.
The locus for the Nth ping only depends on the RTD and the satellite position at that ping time. When you change the starting position, of course you might end up somewhere else but still on the same locus for that ping.

I can't even begin to imagine Inmarsat computing RTD derived loci using an inclined orbit satellite and ignoring satellite motion!!!!

Okay, I have no idea what you're talking about. You did see the slides released by the Malaysian transportation authority with data from Inmarsat via the AAIB right? We are NOT talking about the round-trip time/distance calculation here. I am talking about the Doppler analysis, where they tracked the Doppler shift *over time* and compared it to predictive models based on the movement of similar aircraft in a similar direction. If you want to replicate the measured results from the accident aircraft, the satellite needs to be at the exact same point in its orbit that it was when the accident flight first connected to the network/started pinging/etc! I guess it's literally rocket science, but ... it's not brain surgery!
A man must know how to look before he can hope to see.
 
WarrenPlatts
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 1:09 pm

Quoting Pihero (Reply 252):
Quoting WarrenPlatts (Reply 239):That page you're showing me is a correction you're supposed to make to your LOP when celestially navigating with a bubble sextant.
-
Noi it is the effect of the Coriolis acceleration on an orthofrome.

Quoting WarrenPlatts (Reply 239):. You don't have to worry about it because your GPS powered autopilot does the thinking for you.
I told you about free gyro Navigation, or Polar Path navighation

Listen. I used to do celestial navigation, and not just for fun. This was back in the day before GPS was fully online. Gulf War era. When your ship just does a stupid exercise involving half a dozen 180's that completely destroy you DR plot and the XO is breathing down your neck saying "we need a fix" and the GPS has been down for the last two hours, you have no choice but to break out the sextant. I know how to use it.

The Coriolis correction you're talking about is something you add or subtract to the sextant altitude--the angle between the horizon and whatever star or planet you're looking at. It is only to be applied to a bubble sextant. We did not use those because they are less accurate, but in a bumpy aircraft flying at night, you cannot see the horizon, so you are forced to used a bubble sextant. As you said, the correction is in minutes of a degree. And yes, I know that a minute of a degree on your sextant translates to a nautical mile. But the correction is to a line of position (LOP)--not a great circle track.

Bottom line: The bubble sextant Coriolis correction has NOTHING to do with the Coriolis drift that an aircraft flying inertially, starting from the equator with an initial heading of due south, for 2000 miles would experience.
 
Pihero
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 1:11 pm

Quoting nupogodi (Reply 324):

Sorry buddy, you're 100% incorrect this time! The original arcs assumed a stationary satellite, but the Doppler analysis specifically relied on the satellite's inclination.

In this case, and mind you, I can be wrong, tell me how you determine the derived trajectories from a set of *loci*, LOPs, whatever you name them (Just distances from the satellites) and the radial component of the attached velocity ). To be simple, take no wind trajectories for a start.

I say it again : I 'd like to see the demonstration , or just one demonstration of that method.

IOW, it's a challenge, buddy.   

Quoting nupogodi (Reply 324):
I have been paying attention.

Apparently not to my method.

Quoting nupogodi (Reply 324):
I know some French people don't like Quebecers, but I can assure you, I'm from Ontario

           
Contrail designer
 
nupogodi
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 1:18 pm

Quoting Pihero (Reply 330):
In this case, and mind you, I can be wrong, tell me how you determine the derived trajectories from a set of *loci*, LOPs, whatever you name them (Just distances from the satellites) and the radial component of the attached velocity ). To be simple, take no wind trajectories for a start.

I say it again : I 'd like to see the demonstration , or just one demonstration of that method.

*sigh*

I don't need to, the Inmarsat folks have already done it for you.

http://i.imgur.com/kSXSyW3.jpg
http://i.imgur.com/ZMvCBKs.jpg

You'll notice that they specifically say the difference they plotted is due to the combination of the Doppler shift caused by aircraft motion combined with satellite motion. The satellite moves north and south in a very narrow elliptical orbit about its intended station. If the satellite is moving south when you go do your test flight, but it was moving north when the accident flight was flying, the measured data from the the two aircraft would not match even if their flight paths were identical.

All I am saying is that to replicate their results, which necessarily depend on the movement of the satellite due to its inclined orbit, you also need to replicate the conditions on board the satellite - its position on that orbit.

[Edited 2014-03-29 06:20:00]
A man must know how to look before he can hope to see.
 
WarrenPlatts
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 1:18 pm

Quoting nupogodi (Reply 240):
Quoting WarrenPlatts (Reply 239):You don't have to worry about it because your GPS powered autopilot does the thinking for you.Autopilot? GPS? I'm lucky to have a working radio.

Like I said, if you're flying your 172 on a compass heading, you are compensating for the Coriolis effect without realizing it.
 
Backseater
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 1:23 pm

Quoting nupogodi (Reply 324):
Quoting Pihero (Reply 314):
The NTSB / Inmarsat *loci* are totally independent from a point of origin.

Sorry buddy, you're 100% incorrect this time! The original arcs assumed a stationary satellite, but the Doppler analysis specifically relied on the satellite's inclination.

Isn't the above your original post?
What "original arcs" are you referring to? Are there several? I must have missed something.
 
nupogodi
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 1:30 pm

Quoting BackSeater (Reply 333):
Isn't the above your original post?
What "original arcs" are you referring to? Are there several? I must have missed something.

By "original arcs", I mean the distance from the satellite Inmarsat calculated before they refined their data with Doppler analysis. It was the first piece of the SATCOM ping analysis released. I believe only the 0811L one was released, which showed the aircraft somewhere on roughly a circle with a 40 degree elevation to the satellite. By using known radar data and taking aircraft range into account, parts of that circle could be eliminated as possibilities and what we were left with was two arcs, areas where the aircraft could have been at that time. This left us with the possibility of the "northern track" and the "southern track", and the northern one fueled conspiracy theories. With the Doppler analysis, which took into account the satellite's motion, they were able to model the predicted Doppler shift based on other similar aircraft on similar paths at similar times, and completely discount the northern arc as a possibility.

This narrowed the search area down to the extent of the aircraft's range on the 'southern arc', and now they have revised their calculation for the aircraft's range based on PSR data and so have moved the search area 'further up' the arc.
A man must know how to look before he can hope to see.
 
nupogodi
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 1:40 pm

Pihero, let me remind you of the conversation that started this discussion:

- Someone questioned the possibility of recreating the accident flight
- Someone noted that unless you want to crash another 777, you'll need to take on more fuel
- Someone noted that by removing pax and cargo, you could take on more fuel
- rcair noted that weather and winds aloft would not be identical and would cause a problem for recreating the flight
- I noted that, as well, you would need to fly at exactly the same time in the satellite's orbit to recreate the measured Doppler shift

How we got here from there, I don't know.
A man must know how to look before he can hope to see.
 
Kaiarahi
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 1:40 pm

Quoting nupogodi (Reply 331):

A word of advice, since you've only been on a.net for 3 weeks. There are a number of people on these threads who have earned very widespread respect over the course of years due to their expertise, knowledge and experience. Most of us enjoy learning from them. They enjoy reasoned debate, but not disdain and disrespect. We used to have more - including a flight test engineer who was incredibly knowledgeable about B777 systems, who would have been a great contributor to this discussion - but they've been driven away by disrespect.
Empty vessels make the most noise.
 
Pihero
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 1:41 pm

Quoting WarrenPlatts (Reply 329):

The Coriolis correction you're talking about is something you add or subtract to the sextant altitude--the angle between the horizon and whatever star or planet you're looking at.

Another load of Bull. It's a lateral displacement of your celestial LOP... proof is that, added with the *Curve correction* I mentioned in the same post becomes the total *lateral* displacement of your DR.
(btw, there is no Lat correction on any sextant I've used. IOW, that was a trap... sorry )
... and my experience, being on jets, was with periscopic sextants.

Quoting WarrenPlatts (Reply 329):
an aircraft flying inertially,

Pray tell what that means.

Quoting WarrenPlatts (Reply 329):
But the correction is to a line of position (LOP)--not a great circle track.

How can't you know that a free gyro ( be it a polar compass or a gyrocompass ), corrected for the earth precession, determines an orthodrome...as that correction is by design inside an inertial platform, it means that if one follows an *inertial* track, that track is an orthodrome, the basis for todays' FMGS navigation.

I asked your refs from an Air Force navigator's manual as I'm interested in new ways, methods that were different from the ones I used.
Contrail designer
 
nupogodi
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 1:45 pm

Quoting Kaiarahi (Reply 336):
A word of advice, since you've only been on a.net for 3 weeks. There are a number of people on these threads who have earned very widespread respect over the course of years due to their expertise, knowledge and experience. Most of us enjoy learning from them. They enjoy reasoned debate, but not disdain and disrespect.

I'm not disrespecting anyone. I think there is a communication problem here, since we seem to be talking about completely different things.

Please don't take my exasperated tone as a sign of disrespect.

[Edited 2014-03-29 06:48:54]
A man must know how to look before he can hope to see.
 
Pihero
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 1:54 pm

Quoting nupogodi (Reply 331):
All I am saying

Sorry, buddy.
You have not answered my question. Those links are just about frequency shifts and sat displacement. They certtainly do not give you a trajectorey... So why are these guys so sure of their results and their method ?
On top of that, how did they originally determine the probable tracks without the Doppler infos they got three or four days later ?
To make the question clearer :
- You do not have a heading or a course.
- You do not have a ground speed. You just have times of intersection to different arcs.
- How do you determine a trajectory ?

Plus with the Doppler
- You still haven't got a ground speed, just a radial component of it. Nothing else, albeit accurate it could be.
- How do you determine a trajectory ?

Feel free to use a sheet of paper and your written computations.

[Edited 2014-03-29 06:57:59]
Contrail designer
 
WarrenPlatts
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 1:55 pm

Quote:
Quoting nupogodi (Reply 324):
Sorry buddy, you're 100% incorrect this time! The original arcs assumed a stationary satellite, but the Doppler analysis specifically relied on the satellite's inclination.
In this case, and mind you, I can be wrong, tell me how you determine the derived trajectories from a set of *loci*, LOPs, whatever you name them (Just distances from the satellites) and the radial component of the attached velocity ). To be simple, take no wind trajectories for a start.

I say it again : I 'd like to see the demonstration , or just one demonstration of that method.

IOW, it's a challenge, buddy. [/quote]



For a series of circular LOPs, assuming a given, constant speed, a general direction, and straight lines between LOPs, there is only one track. Different speeds will generate different, but unique tracks. All the Doppler does is say which track is the more plausible. As for the relation of the inclination's effect on the LOPs, the satellite only moves a degree or two: therefore, the effect is within the error (plus or minus a hundred miles), and doesn't materially affect where to draw the LOP.
 
nupogodi
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 2:00 pm

Quoting Pihero (Reply 339):
- How do you determine a trajectory ?

I'm not saying anything about determining a trajectory, friend. I am not sure why we have our wires crossed here. You may have had my original reply that spawned this confused with a reply to something else, but as I outlined above, all I was talking about was the idea someone floated of *potentially* recreating the accident flight. You know, flying an identical aircraft on potential trajectories and seeing what fits? I said that to do that, you would need to match the satellite's position in its orbit.

I said nothing about calculating trajectories. I am aware that even with the best analysis in the world, all you're going to get from Doppler+round-trip-time is a wide range of possible trajectories.

edit: To somewhat answer your question, I believe they used an assumed ground speed + the aircraft's range to calculate their potential trajectories. Assuming it more or less flies in a straight line, changing the speed changes the extent of where the aircraft could be on that "final ping" arc, which is why the map they released had two potential tracks, one at 400kt and one at 450kt.

[Edited 2014-03-29 07:06:27]
A man must know how to look before he can hope to see.
 
Pihero
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 2:07 pm

Quoting WarrenPlatts (Reply 340):
For a series of circular LOPs, assuming a given, constant speed, a general direction, and straight lines between LOPs, there is only one track.

I totally agree with the method.

Quoting WarrenPlatts (Reply 340):
. As for the relation of the inclination's effect on the LOPs, the satellite only moves a degree or two: therefore, the effect is within the error (plus or minus a hundred miles)

Agreed, but the Inmarsat people are quite confident - and do not doubt them one millisecond - that they've nailed the shifts to a precision of  
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Finn350
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 2:16 pm

Quoting WarrenPlatts (Reply 340):
Different speeds will generate different, but unique tracks. All the Doppler does is say which track is the more plausible.

As stated in the Inmarsat graphs:

Quote:
D2 is a combination of the Doppler components due to the satellite motion, which is accurately known, and the aircraft heading and speed. Using the burst frequency offsets measured at the land earth station, it is possible to compare against the predictions for aircraft heading and speed.

Inmarsat clearly states that the satellite's motion is known. When the trajectory of the satellite is known, the Doppler shift component induced by the satellite's motion can be eliminated and the remaining Doppler shift component is resulting from the aircraft's motion alone.

As you say, one has to assume a ground speed, as only the radial component of the velocity can be determined from the Doppler shift. If you assume a ground speed, there is only one tangential velocity component and thus a heading consistent with that ground speed and the radial velocity component.

They have apparently select a TAS of 400 knots (which corresponds to some other ground speed when taking winds into account). It might that the Doppler shift measurement is not precise enough to select a heading with a great accuracy, though.
 
Backseater
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 2:23 pm

Quoting nupogodi (Reply 334):
By "original arcs", I mean the distance from the satellite Inmarsat calculated before they refined their data with Doppler analysis.

Thank you for the lecture on what you know that I know full well as I also explained all this in earlier posts. Your post #324 as originally written did not make sense to me. Notice it did not confuse me but it might have confused others casually reading what you wrote.

Anyway if those in the know do not want to release the RTD, margin of error and aircraft (not composite) Doppler data, there in no point IMO trying to speculate about possible tracks through the Indian Ocean. When the northern arc had not yet been eliminated, I could possibly understand why such data might not be released. But now that only the southern arc over the ocean is feasible, WHAT IS THE BIG SECRET?

In fact, who owns the data?
- Inmarsat? Probably not because even though the ping came from Inmarsat ES, the actual response was generated by the MAS aircraft owned by their customer. Sat operators cannot release to third parties the positioning data of their customers' mobiles, unless that data is requested under a Court order.
- MAS? Would they be any happier without all that data? In the end, that data should help lift the veil of mystery and possibly increase MAS financial exposure?
- the Ministry of Transportation of Malaysia? They control what is released as it is part of their official investigation. I suppose they could also stuff it into their "sealed evidence file", ensuring that not too many people will ever see it.
 
panampaul
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 2:29 pm

In today's Australian maritime safety agency report, it turns out that the ships are finding objects but nothing MH370 related.

Planes continue to spot possible MH370 debris.

More Ships Head to Flight 370 Search Area - So Far Objects Recovered by Ships Not from Missing Plane

Quote:
As the search for Malaysia Airlines Fight 370 drew to a close Saturday, a small flotilla of ships was headed to the newly-identified search area in the southern Indian Ocean where officials believe the plane may be found, while officials conducting the search reported that new items were spotted floating in the sea.

Authorities said that three additional ships had arrived on Saturday and more were scheduled to join the search Sunday, bringing the total number to nine. More are scheduled to arrive at the beginning of the week, according to Australian officials managing the search.

In a statement released midday Saturday, the Australian Maritime Safety Authority said 252,000 square kilometers (97,297 square miles) were searched on Saturday....
 
WarrenPlatts
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 2:39 pm

Quoting Pihero (Reply 337):
Quoting WarrenPlatts (Reply 329):
The Coriolis correction you're talking about is something you add or subtract to the sextant altitude--the angle between the horizon and whatever star or planet you're looking at.
Another load of Bull. It's a lateral displacement of your celestial LOP...

It's both! A minute correction to your sextant angle translates to a nautical mile lateral displacement of your celestial LOP.

Quoting Pihero (Reply 337):
Quoting WarrenPlatts (Reply 329):an aircraft flying inertially,
Pray tell what that means.

Again: it's an aircraft (or submarine) whose only heading is dead ahead, regardless of compass heading, the Earth's surface, or way points.

Quoting Pihero (Reply 337):
if one follows an *inertial* track, that track is an orthodrome

No, most emphatically, an inertial track is not a great circle track. An inertial track is a function of speed and the Coriolis effect. In the northern hemisphere, it will bend to the right; in the southern hemisphere it will bend to the left. In order to navigate a great circle track, the Coriolis effect must be compensated for.

Quoting Pihero (Reply 337):
... and my experience, being on jets, was with periscopic sextants.

The principle is the same as a bubble sextant. Since you're not measuring the angle WRT the visible horizon, you must measure the angle WRT what feels like flat level based on gravity. But because you are moving in a rotating reference frame, what feels like level is not absolutely level WRT the Earth's surface. E.g., if you're flying wings level at 450 knots at 45 degrees south, you're actually tilted by 8.5' WRT the Earth's surface. Thus you make the Coriolis correction to your sextant angle/LOP.

Quoting Pihero (Reply 337):
I asked your refs from an Air Force navigator's manual as I'm interested in new ways, methods that were different from the ones I used.

We used Dutton's as our primary reference, although I believe we kept a copy of the Air Almanac in the chartroom library.
 
canoecarrier
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 3:02 pm

Quoting nupogodi (Reply 338):

I have to agree with Kahaiari. This accident has brought a lot of new people to the forum who have run up some abnormally high post counts in under a month. There are some very intelligent, professional aviators that post here. Let's not run them away.
The beatings will continue until morale improves
 
nupogodi
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 3:29 pm

Quoting canoecarrier (Reply 347):
I have to agree with Kahaiari. This accident has brought a lot of new people to the forum who have run up some abnormally high post counts in under a month. There are some very intelligent, professional aviators that post here. Let's not run them away.

Kind of unfair to jump on me, guys, as 'running' professionals away. I appreciate Pihero's contributions, clearly a very intelligent and knowledgeable person. But what I was saying was correct, and I think the exchange was basically due to a failure in communicating properly. All I was talking about was how you would recreate the data with a test flight, and it's true that the satellite's position in orbit is crucial to that. There can be no objection to that, it's the factor that allows you to break the symmetry. Did not mean to offend anyone, just get prickly when I'm misunderstood. My post count may be high (and the number of posts on this topic in general have been high) but I think my contributions have been high-quality as well.

Don't mistake my desire for factual information to stand as disrespect or anything of the sort. We all want the same thing here, a better understanding of what occurred.
A man must know how to look before he can hope to see.
 
comorin
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RE: MH370 Malaysia Airlines B772 Missing Enroute KUL-PEK Part 47

Sat Mar 29, 2014 3:38 pm

Quoting canoecarrier (Reply 347):

Agreed. To advise the Head Moderator to look up something on Wikipedia is impertinent.   

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