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'Pilotless Jumbo Seconds From Disaster" At VHHH  
User currently offlinePolAir From United States of America, joined May 2001, 893 posts, RR: 2
Posted (9 years 9 months 1 week 4 days 20 hours ago) and read 15102 times:

I am not sure when that happened, but article is dated today, so must be fairly new.

http://www.telegraph.co.uk/news/main...t=/portal/2004/10/14/ixportal.html


I don't get it. So all pilots left the cockpit after go around? If not, why nobody answered ATC? Can 747, even relatively light, sustain 120 knots (130mph) or is it just pure media imagination? What do you guys think?

41 replies: All unread, showing first 25:
 
User currently offlineDLKAPA From , joined Dec 1969, posts, RR:
Reply 1, posted (9 years 9 months 1 week 4 days 20 hours ago) and read 15058 times:

Show me a 747 doing 120 knots and I will show you a hole in the ground.

User currently offlineDoug_Or From United States of America, joined Mar 2000, 3441 posts, RR: 3
Reply 2, posted (9 years 9 months 1 week 4 days 20 hours ago) and read 15038 times:

Did you read the article? The autopilot disconnected and the pilots didn't know it.


When in doubt, one B pump off
User currently offlinePolAir From United States of America, joined May 2001, 893 posts, RR: 2
Reply 3, posted (9 years 9 months 1 week 4 days 20 hours ago) and read 15023 times:

Did not read this closely. Crew was in the cockpit. However, didnt they feel steep climb/loss of speed? I assume visibility was poor.

User currently offlineOzGlobal From France, joined Nov 2004, 2732 posts, RR: 4
Reply 4, posted (9 years 9 months 1 week 4 days 20 hours ago) and read 15007 times:

This happened four months ago from memory. The article is dated, if you look carefully, 14/10/2004. Today's date is being automatically displayed on the webpage.

[Edited 2005-03-14 02:36:11]


When all's said and done, there'll be more said than done.
User currently offlineDLKAPA From , joined Dec 1969, posts, RR:
Reply 5, posted (9 years 9 months 1 week 4 days 20 hours ago) and read 14984 times:

The article also said that the aircraft was doing 120 knots (130mph) in a 30* Roll and because of the roll AVOIDED the stall. That's physically impossible, the roll would cause the wing to be less efficient in lifting the plane (hence why when you turn an aircraft in flight you also pull back on the yoke to give it a slightly noze-high angle of attack), thus the airplane would have fallen to the ground in a nice sliding corkscrew action.

Ok, so maybe it's possible for an empty 747 to be doing 120kts in flight, provided it's the phase of flight known as "Flare" and the thing is inches above a runway, but comeon, a 747 loaded with 350 pax doing a 30* bank at 120kts, no way!

[Edited 2005-03-14 02:37:11]

User currently offlineDoug_Or From United States of America, joined Mar 2000, 3441 posts, RR: 3
Reply 6, posted (9 years 9 months 1 week 4 days 19 hours ago) and read 14938 times:

DLKAPA, Chill! My response was written when there were no replies. I was reacting to the question about the crew not being in the cockpit.

However, if you enter a roll , like you say, you need to apply an up elevator input. Otherwise the nose drops. Since the pilots didn't apply any backpreasure, the nose did drop and so the angle of attack was reduced.



When in doubt, one B pump off
User currently offlineDLKAPA From , joined Dec 1969, posts, RR:
Reply 7, posted (9 years 9 months 1 week 4 days 19 hours ago) and read 14683 times:

Quoting Doug_Or (Reply 6):
However, if you enter a roll , like you say, you need to apply an up elevator input. Otherwise the nose drops. Since the pilots didn't apply any backpreasure, the nose did drop and so the angle of attack was reduced.

True, but according to the article, the noze didn't drop until at or near 120kts airspeed. I'm pretty sure a 747 flying with a decent pax load will stall well before that.


User currently offlineHAWK21M From India, joined Jan 2001, 31702 posts, RR: 56
Reply 8, posted (9 years 9 months 1 week 4 days 17 hours ago) and read 14437 times:

How did the News reach this "Aviation Correspondent" BTW.
regds
MEL



Think of the brighter side!
User currently offline727EMflyer From United States of America, joined Mar 2005, 547 posts, RR: 0
Reply 9, posted (9 years 9 months 1 week 4 days 17 hours ago) and read 14390 times:

Keep in mind this story is coming to us via the media... the most often flamed contributor at a.net. I would guess the 130 MPH quoted speed was groundspeed. Given all the variables like wind and angle of climb, the aircraft could have been in much better shape airspeed wise. Either way if the course the plane took is anywhere close to that shown in the articles graphic, shame shame shame on the flightcrew. When did crew stop being pilots and start being mere "airplane operators?"

User currently offlineFriendlySkies From United States of America, joined Aug 2004, 4120 posts, RR: 5
Reply 10, posted (9 years 9 months 1 week 4 days 17 hours ago) and read 14326 times:

Quoting 727EMflyer (Reply 9):
I would guess the 130 MPH quoted speed was groundspeed.

Not to be nit-picky, but isn't groundspeed usually HIGHER than airspeed?


User currently offlineDLKAPA From , joined Dec 1969, posts, RR:
Reply 11, posted (9 years 9 months 1 week 4 days 16 hours ago) and read 14230 times:

Quoting FriendlySkies (Reply 10):
Not to be nit-picky, but isn't groundspeed usually HIGHER than airspeed?

Depends on the winds. Airspeed is really a measurement of Ram Air Pressure into the aircraft's Pitot tubes, so if there is a strong headwind, the measurement of the rate at which the aircraft cuts through the air will be higher. The airspeed will always be higher than the groundspeed in the event of a headwind.

Generally, one way to think about a headwind is "Free Airspeed." If you are rolling down a runway with a 30kt headwind, you can lift off the runway going 30kts slower than your normal takeoff speed with no headwind. The same works for landing, as it's much easier to make a soft touchdown with the same 30kt headwind (provided it's an almost direct headwind), because you are again travelling 30kts slower than normal touchdown speed.


User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 12, posted (9 years 9 months 1 week 4 days 16 hours ago) and read 14186 times:

Sorry to be a nay sayer, but airspeed really doesn't have a lot to do with stalls. What is relevant is the angle of attack. I can have 0 angle of attack on an airplane and 0 airspeed and I am not in a stalled condition.

I can assure you depending on the flap configuration, with full thrust and 130 mph (kias more likely) the airplane probably flying fine.

Remember this incident is really very old news. It was on PPRUNE for a while and I am sure if you want search the archives on there you will probably get a better idea of what happened.


User currently offlineDLKAPA From , joined Dec 1969, posts, RR:
Reply 13, posted (9 years 9 months 1 week 4 days 16 hours ago) and read 14161 times:

Quoting PhilSquares (Reply 12):
I can have 0 angle of attack on an airplane and 0 airspeed and I am not in a stalled condition.

When you're sitting on the ground parked, yes. I find it very hard to believe that any airplane in flight could be at 0 angle of attack and have 0 airspeed while not being in a stalled condition.


User currently offlineDoug_Or From United States of America, joined Mar 2000, 3441 posts, RR: 3
Reply 14, posted (9 years 9 months 1 week 4 days 16 hours ago) and read 14112 times:

Quoting DLKAPA (Reply 13):
I find it very hard to believe that any airplane in flight could be at 0 angle of attack and have 0 airspeed while not being in a stalled condition

Well you'll just have to work on that. Stall is caused by one thing- angle of attack. In normal 1 g flight, angle of attack needs to increased as airspeed decreases, just as AoA must be increased when weight is increased. However, when in less than 1 G flight- like, I don't know- when the nose is coming down, the AoA @ a given airspeed will be lower, and therefore further from stalling.

RE: Airspeed vs ground speed, there are two basic kinds of airspeed indicated (IAS, the ram preasure you talked about) and true airspeed (TAS, the actaul speed of the aircraft moving through the air). Statisticaly, TAS will on average be average be faster that ground speed, becasue more than half of the potential wind vecotors result in a reduction in groundspeed. However, as altitude increases, IAS goes down @ a given TAS, and therefore will most likely be less than GS.



When in doubt, one B pump off
User currently offlineGoBoeing From United States of America, joined Jun 2000, 2725 posts, RR: 15
Reply 15, posted (9 years 9 months 1 week 4 days 16 hours ago) and read 14102 times:

Quoting DLKAPA (Reply 13):
I find it very hard to believe that any airplane in flight could be at 0 angle of attack and have 0 airspeed while not being in a stalled condition.

Try this, you might like it:


View Large View Medium
Click here for bigger photo!

Photo © Jean



Nick


User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 16, posted (9 years 9 months 1 week 4 days 16 hours ago) and read 14086 times:

DKKAPA,

What happens when you "unload" an airplane?

The angle of attack approaches 0. The wings are producing no lift, so you have no induced drag. All your thrust is being converted to potential energy.

When I flew fighters you tried to do all your maneuvering in the vertical. It's the best way to conserve/make energy. It was not uncommon to go vertical, unload and have your airspeed bleed down to 0. When I was a T-38 instructor, you tried to teach energy management and that was a great demo to go to mil power and unload and watch the airspeed go to 0 and the angle of attack go to 0.


User currently offlineDLKAPA From , joined Dec 1969, posts, RR:
Reply 17, posted (9 years 9 months 1 week 4 days 15 hours ago) and read 13965 times:

Ahh... I'm LEARNDING!!! Big grin

One more question though

Quoting PhilSquares (Reply 16):
The angle of attack approaches 0. The wings are producing no lift

I'm probably missing something here, but isn't the plane technically in a "stall" if the wings are producing no lift?


User currently offline707437 From United States of America, joined Nov 2003, 152 posts, RR: 1
Reply 18, posted (9 years 9 months 1 week 4 days 14 hours ago) and read 13912 times:

No load means you need no lift to maintain altitude so no problem right?

So as long as your momentum is holding the airplane up who even needs a wing anyway. . .

But realistically when the lift is slightly less than the weight of the aircraft you've got a controlled mild descent.

But when these numbers diverge seriously. . . Then the flow separates across the airfoil and game over.

That's my take on it. . .


User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 19, posted (9 years 9 months 1 week 4 days 14 hours ago) and read 13840 times:

The reason the wings are producing no lift is you are in a 0G, or close to it, environment. So as the g-load approaches 0 the demand for lift on the wings decreases (read angle of attack). Conversely, a 60 degree bank level turn, will give you a 2 G load. Now you have to have back pressure on the stick (yoke) to increase your angle of attack. If you add no power, you will lose airspeed, and have a greater need for back pressure. Now you are increasing the angle of attack to produce the same amount of lift at a lower airspeed. I have felt buffet on the airframe at over 500 KIAS while maneuvering. Why? Because I was approaching the Max AOA. Now you have an accelerated stall.

Hope that helps. If not just ask here or send me an email.


User currently offlineDLKAPA From , joined Dec 1969, posts, RR:
Reply 20, posted (9 years 9 months 1 week 4 days 13 hours ago) and read 13567 times:

That is all my fragile little mind can handle tonight...

Thanks dude!


User currently offlineOly720man From United Kingdom, joined May 2004, 6843 posts, RR: 11
Reply 21, posted (9 years 9 months 1 week 4 days 12 hours ago) and read 12826 times:

Interesting caption on the little graphic..... "Near miss for Britons on Cathay Pacific flight to Hong Kong."

Were the other nationalities perfectly safe then??



wheat and dairy can screw up your brain
User currently offlineMEA-707 From Netherlands, joined Nov 1999, 4358 posts, RR: 35
Reply 22, posted (9 years 9 months 1 week 4 days 8 hours ago) and read 11253 times:

Yeah, that's a hilarious caption, typically the UK tabloid, like that the Britons on board make the story connect more to their reader base, they presume the reader might otherwise raised his shoulder "who cares about some shaded eyed people in some bamboo airplane"


nobody has ever died from hard work, but why take the risk?
User currently offlineDAYflyer From United States of America, joined Sep 2004, 3807 posts, RR: 3
Reply 23, posted (9 years 9 months 1 week 4 days 6 hours ago) and read 10014 times:

Quoting DLKAPA (Reply 5):
The article also said that the aircraft was doing 120 knots (130mph) in a 30* Roll and because of the roll AVOIDED the stall. That's physically impossible, the roll would cause the wing to be less efficient in lifting the plane (hence why when you turn an aircraft in flight you also pull back on the yoke to give it a slightly noze-high angle of attack), thus the airplane would have fallen to the ground in a nice sliding corkscrew action.

Ok, so maybe it's possible for an empty 747 to be doing 120kts in flight, provided it's the phase of flight known as "Flare" and the thing is inches above a runway, but comeon, a 747 loaded with 350 pax doing a 30* bank at 120kts, no way!

I believe in a dirty configuration it must maintain a minimum of 140 knots to remain airborne.



One Nation Under God
User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 24, posted (9 years 9 months 1 week 4 days 6 hours ago) and read 9965 times:

Quoting DAYflyer (Reply 23):
I believe in a dirty configuration it must maintain a minimum of 140 knots to remain airborne.

Believe me, it will continue to fly well below the 140 Knots you mention!!!! Again, it's not speed, but angle of attack.


25 Post contains images DLKAPA : Nope! Last night after reading this thread I decided to test this theory in a fully loaded 744 in flightsim. I did a touch and go and pulled the plan
26 B742 : Lucky escape there! I was at Kai Tak when the China Airlines 747 overran the runway, not a pretty sight! Good job we didn't have another HKG disaster!
27 Powerofpi : I wonder if they retracted the flaps like they were supposed to. Once I was on a 737 and we did a go-around. I know it's not a 747, but I was pretty a
28 Doug_Or : It might be possible they had partialy retracted the flaps. I don't know anything about 747 automation (or lack there of), but in the Boeing I'm famil
29 Rootsgirl : Did you read the post? Start your own post about rolls etc and someone answer the question. It involves the crew in the flight deck. Ignoring the ques
30 DLKAPA : Neither is coming into a thread 30 replies in and trying to tell us what the topic should be.
31 Stealthpilot : The article also mentioned that the aircraft had a pitch (not bank) of 28 degrees. That seems scarier than a 30 bank!! Does anyone know the critical a
32 BuckFifty : This makes me really wonder what the hell the pilots were doing up there because obviously you don't leave full flaps in on a go around. Who was respo
33 VEEREF : Actually we'll be seeing this headline again on a regular basis some time in the future when pilots are removed from aviation...........
34 VEEREF : The scary part of this event, assuming the numbers are correct, is the degree to which the crew lost situational awareness of what mode they were oper
35 Post contains images LAPA_SAAB340 : Hi Stealth One detail you have to be careful about is that angle of attack is not the same thing as pitch angle - it is not affected by where the nose
36 Post contains images Stealthpilot : LAPA_SAAB = Correct you are, the angle of attack is the angle to the relative wind Nevertheless, what is the critical angle? -Nikhil
37 PhilSquares : There is no angle of attack indicator on the 744. In addition, it would depend on other factors such as gross wight and g loading (bank angle). Howeve
38 Airlinelover : Most passengers disembarked without realising they had been so near to disaster. Until now.. That's crazy.. Pilots must have been wasted or something.
39 PhilSquares : I am amazed at all the experts on this forum. If there are so many experts, why has no one suggested an autopilot malfunction? No, that couldn't happe
40 Post contains images DLKAPA : They did, hence very few members of this forum will ever find their way into a cockpit
41 Doug_Or : "but I can land in MSFS9, so anytime anything goes wrong anywhere its becuause they are incometpant and should be fired"
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