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How Might Have An A330 Have Responded In BA038?  
User currently offlineMotopolitico From United States of America, joined Dec 2005, 212 posts, RR: 0
Posted (6 years 2 months 6 days 19 hours ago) and read 4618 times:

I know this may well be an exercise in futility, but given the apparent situation of BA038, dual engine failure 40 seconds from landing, and a FO who appears to have pushed his aircraft to the limit to get it across the fence, would an A330 in a similar situation with Airbus' envelope protection have fared better or worse?


Garbage stinks; trash don't!
63 replies: All unread, showing first 25:
 
User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 1, posted (6 years 2 months 6 days 19 hours ago) and read 4613 times:



Quoting Motopolitico (Thread starter):
I know this may well be an exercise in futility, but given the apparent situation of BA038, dual engine failure 40 seconds from landing, and a FO who appears to have pushed his aircraft to the limit to get it across the fence, would an A330 in a similar situation with Airbus' envelope protection have fared better or worse?

Considering the aircraft are both FBW, I don't think it would have made any difference at all. ?????


User currently offlineDH106 From United Kingdom, joined Jun 2005, 623 posts, RR: 1
Reply 2, posted (6 years 2 months 6 days 18 hours ago) and read 4605 times:
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Yes, but as I understand it Airbus has a 'hard' envelope protection whilst Boeing allows pilots the final say - exceeding the envelope if commanded. Assuming similar glide ratios it boils down to:

1) the margin (if any) that Airbus allows at the envelope limits
2) how 'accurately' the F/O flew the B777 at it's perfomrance limits



...I watched c-beams glitter in the dark near the Tanhauser Gate....
User currently offlineMotopolitico From United States of America, joined Dec 2005, 212 posts, RR: 0
Reply 3, posted (6 years 2 months 6 days 18 hours ago) and read 4598 times:

Ah! I hadn't considered differing glide characteristics. There's clearly a lot more to the question than I thought when I asked it. I guess what I really meant to ask was how would BA038 have done if the T7 had had Airbus-style hard envelope protection. I suppose the world will never know.


Garbage stinks; trash don't!
User currently offlineRJ111 From , joined Dec 1969, posts, RR:
Reply 4, posted (6 years 2 months 6 days 18 hours ago) and read 4581 times:

I think it's quite important to establish all the facts of the incident first before we speculate on how an Airbus would have performed.

User currently offlineDH106 From United Kingdom, joined Jun 2005, 623 posts, RR: 1
Reply 5, posted (6 years 2 months 6 days 18 hours ago) and read 4575 times:
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Quoting RJ111 (Reply 4):
I think it's quite important to establish all the facts of the incident first before we speculate on how an Airbus would have performed.

Definitely agreed.



...I watched c-beams glitter in the dark near the Tanhauser Gate....
User currently offlineStarlionblue From Greenland, joined Feb 2004, 16908 posts, RR: 67
Reply 6, posted (6 years 2 months 6 days 17 hours ago) and read 4551 times:



Quoting RJ111 (Reply 4):
I think it's quite important to establish all the facts of the incident first before we speculate on how an Airbus would have performed.

As long as it's understood we're speculating with incomplete information, I don't think it's really a problem.

So here's my speculative answer.
As far as flying characteristics, an 330 would have behaved the same way after the "lack of power-up". Envelope protection would only have come into play is the aircraft had been entering a stall.

If the aircraft had been entering a stall, the 777 would have activated the stick shaker (right?) and the trusted the pilots to do the right thing. The 330 would have prevented the stall altogether by lowering the nose.

It's also important to remember that Airbus envelope protection is there to make the aircraft safer. Preventing a stall at low altitude ensures the plane hits the ground wings level and controlled (as in the notorious Mulhouse 320 crash) as opposed to flipping end over end. Envelope protection is not a suicide pact. It is not the case of a French computer suddenly intoning (cue French movie villain voice): "I don't wanna talk to you no more, you empty headed animal food trough wiper! I fart in your general direction! Your mother was a hamster and your father smelt of elderberries!"

Anyway...



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineSEPilot From United States of America, joined Dec 2006, 6682 posts, RR: 46
Reply 7, posted (6 years 2 months 6 days 12 hours ago) and read 4451 times:



Quoting Starlionblue (Reply 6):
"I don't wanna talk to you no more, you empty headed animal food trough wiper! I fart in your general direction! Your mother was a hamster and your father smelt of elderberries!"

 bigthumbsup 
Good summary. I suspect that your conclusion is correct; the pilot in the 777 did not exceed the envelope that an Airbus would have enforced; if he had the 777 would almost certainly have stalled and crashed. The only situation I can envision where the envelope protection of the Airbus could stand in the way of a successful outcome would be a violent maneuver to avoid a collision. But there may arise some other situation, which is what Boeing feels. They do not consider themselves smart enough to foresee every situation, and thus leave ultimate control to the pilot.



The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
User currently offlineDH106 From United Kingdom, joined Jun 2005, 623 posts, RR: 1
Reply 8, posted (6 years 2 months 6 days 10 hours ago) and read 4393 times:
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Quoting SEPilot (Reply 7):
I suspect that your conclusion is correct; the pilot in the 777 did not exceed the envelope that an Airbus would have enforced; if he had the 777 would almost certainly have stalled and crashed

Do we know the B777 didn't in fact stall ?
I'm speculating , but it may well have stalled from quite a low height and 'just' carried over the fence. The initial grooves at the point in the earth of the runway undershoot seemed quite deep to me which might imply a fairly high vertical descent speed at touchdown and the state of the gear afterwards seems to reinforce this - the left gear looked as though it had been fairly brutally forced up through the wing rather than just drag damage from running over rough unprepared ground.
I'm not taking anything away from the skill of the F/O here - it was certainly a disaster averted.
Be interesting to see what the report says..



...I watched c-beams glitter in the dark near the Tanhauser Gate....
User currently offlineMoo From Falkland Islands, joined May 2007, 3829 posts, RR: 5
Reply 9, posted (6 years 2 months 6 days 9 hours ago) and read 4367 times:



Quoting SEPilot (Reply 7):
the pilot in the 777 did not exceed the envelope that an Airbus would have enforced;

There is also no guarantee that the Airbus FBW system would have enforced anything - the aircraft would have been in an unknown state, and Airbus FBW (like Boeings) has several modes of operation, one of which includes 'get out of the pilots way and play no part other than to pass messages between pilot and control surfaces' (Direct Law).


User currently offlineKELPkid From United States of America, joined Nov 2005, 6265 posts, RR: 3
Reply 10, posted (6 years 2 months 6 days 7 hours ago) and read 4261 times:



Quoting Starlionblue (Reply 6):
"I don't wanna talk to you no more, you empty headed animal food trough wiper! I fart in your general direction! Your mother was a hamster and your father smelt of elderberries!"

What's next, livestock being catapulted over the wall?  mischievous 



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineStarlionblue From Greenland, joined Feb 2004, 16908 posts, RR: 67
Reply 11, posted (6 years 2 months 6 days 6 hours ago) and read 4233 times:



Quoting Moo (Reply 9):

There is also no guarantee that the Airbus FBW system would have enforced anything - the aircraft would have been in an unknown state, and Airbus FBW (like Boeings) has several modes of operation, one of which includes 'get out of the pilots way and play no part other than to pass messages between pilot and control surfaces' (Direct Law).

It would not have been in an unknown state. Direct Law is only used if you lose quite a few control systems and power systems. Assuming the engines were the only affected system, the aircraft would have remained in Normal Law.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineRoseFlyer From United States of America, joined Feb 2004, 9379 posts, RR: 52
Reply 12, posted (6 years 2 months 6 days 6 hours ago) and read 4224 times:

Quoting PhilSquares (Reply 1):

Considering the aircraft are both FBW, I don't think it would have made any difference at all. ?????

The 777 has a slightly different manual reversion should certain FBW be lost. What that means is that there are a few cables running to certain control surfaces. However at this point it isn't believed that the FBW system was lost, so that point is not important.

Quoting Starlionblue (Reply 6):
If the aircraft had been entering a stall, the 777 would have activated the stick shaker (right?) and the trusted the pilots to do the right thing. The 330 would have prevented the stall altogether by lowering the nose.

It takes about 70lbs of back pressure to make a 777 stall. The computer will let you do it, but you have to put a lot of work into stalling a 777. 70lbs of force means that you basically have your feet up and are pulling with all your might. The stick shaker of course is going off along with visual and verbal master alarms and cautions. I've never been in a 777 when it has stalled, but I hear it is made to be very difficult.

[Edited 2008-02-15 16:38:39]


If you have never designed an airplane part before, let the real designers do the work!
User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 13, posted (6 years 2 months 6 days 6 hours ago) and read 4216 times:



Quoting PhilSquares (Reply 1):
Considering the aircraft are both FBW, I don't think it would have made any difference at all. ?????

FBW means that electrical signals are used to tell the flight control servos where to position the control surface (by supplying hydraulic fluid to the actuators) rather than controls cables. So FBW nothing to do with the incident.

Quoting Starlionblue (Reply 11):
It would not have been in an unknown state. Direct Law is only used if you lose quite a few control systems and power systems. Assuming the engines were the only affected system, the aircraft would have remained in Normal Law.

There is nothing "Normal" about loosing forward thrust when the wing is as dirty as BA038's.

Quoting RoseFlyer (Reply 12):
The 777 has manual reversion should FBW be lost.

I need a explanation of how this is possible?


User currently offlineRoseFlyer From United States of America, joined Feb 2004, 9379 posts, RR: 52
Reply 14, posted (6 years 2 months 6 days 5 hours ago) and read 4209 times:

Quoting 474218 (Reply 13):
Quoting RoseFlyer (Reply 12):
The 777 has manual reversion should FBW be lost.

I need a explanation of how this is possible?

I'm not exactly sure how it works, but I'll ask around when I'm at work on Monday. What I do know is that Boeing's Fly By Wire on the 777 is different than the Airbus model and that there are differences in how the backup systems work. I think I chose my words incorrectly since it does not have manual reversion in the sense of the 737. I could be wrong though since I'm not an expert on the 777. What I have been told is from a coworker who worked on the early design of the 777.

[Edited 2008-02-15 16:36:46]


If you have never designed an airplane part before, let the real designers do the work!
User currently offlineDw747400 From United States of America, joined Aug 2001, 1254 posts, RR: 1
Reply 15, posted (6 years 2 months 6 days 5 hours ago) and read 4188 times:



Quoting 474218 (Reply 13):
I need a explanation of how this is possible?

Direct linkages that bypass the FBW system entirely. I know a 777 has to spoilers hooked up for non-FBW roll control, and I think either the elevator or the elevator trim can be manually actuated as well.

Does anyone know what an A330 would do if it lost both engines? Does the envelope protection stay engaged, or will it go back to another mode (normal mode, direct mode--whatever it is you avionics experts call it).



CFI--Certfied Freakin Idiot
User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 16, posted (6 years 2 months 6 days 5 hours ago) and read 4179 times:



Quoting Dw747400 (Reply 15):
Direct linkages that bypass the FBW system entirely. I know a 777 has to spoilers hooked up for non-FBW roll control, and I think either the elevator or the elevator trim can be manually actuated as well.

So the 777 has control cables, bell-cranks and push rods, just like a non-FBW aircraft, except they are only used for back-up?


User currently offlineBuyantUkhaa From Mongolia, joined May 2004, 2828 posts, RR: 3
Reply 17, posted (6 years 2 months 6 days 4 hours ago) and read 4167 times:



Quoting Starlionblue (Reply 6):
t is not the case of a French computer suddenly intoning (cue French movie villain voice): "I don't wanna talk to you no more, you empty headed animal food trough wiper! I fart in your general direction! Your mother was a hamster and your father smelt of elderberries!"

What a strange person!

If the BA777 weighs the same as a duck... (see signature)



I scratch my head, therefore I am.
User currently offlineZeke From Hong Kong, joined Dec 2006, 8643 posts, RR: 75
Reply 18, posted (6 years 2 months 6 days 4 hours ago) and read 4147 times:



Quoting Motopolitico (Thread starter):
Yes, but as I understand it Airbus has a 'hard' envelope protection whilst Boeing allows pilots the final say - exceeding the envelope if commanded. Assuming similar glide ratios it boils down to:

1) the margin (if any) that Airbus allows at the envelope limits
2) how 'accurately' the F/O flew the B777 at it's perfomrance limits

Because of the envelope protection that is on the Airbus, it has a lower stall buffet than similar aircraft, it is one of the reasons why the Airbus FBW outperforms the Boeing FBW on maneuvers like a CFIT recovery. With the engines still developing thrust, as it was in this case, it would be possible to fly a A330 in landing configuration at stall speed without a risk the aircraft from stalling. One would not fly the aircraft so slow, as flying at that speed would actually increase your descent rate, and reduce performance.

Quoting RJ111 (Reply 4):
I think it's quite important to establish all the facts of the incident first before we speculate on how an Airbus would have performed.

Agreed 100%

Quoting Starlionblue (Reply 11):
It would not have been in an unknown state. Direct Law is only used if you lose quite a few control systems and power systems. Assuming the engines were the only affected system, the aircraft would have remained in Normal Law.

It is not an unknown state with all engines failed, with an all engine flame out you are in direct law because of the loss of electrical buses and hydraulics, the FBW protections are not in place, Airbus has a QRH procedure for this (unlike the 777). With engines still developing thrust as it appears in this accident, a A330 in a similar case would still be in normal law as the electrics and hydraulics are normally powered.

Quoting RoseFlyer (Reply 12):
The 777 has a slightly different manual reversion should certain FBW be lost. What that means is that there are a few cables running to certain control surfaces. However at this point it isn't believed that the FBW system was lost, so that point is not important.

It is difficult to say what would be lost with a dual engine flame out, Boeing does not have a procedure for dual engine flame out on the 777 in their QRH or FCOM 3. With engines still developing thrust, nothing would have been lost at all on a 777 or A330.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 19, posted (6 years 2 months 6 days 4 hours ago) and read 4148 times:



Quoting 474218 (Reply 13):


Quoting PhilSquares (Reply 1):
Considering the aircraft are both FBW, I don't think it would have made any difference at all. ?????

FBW means that electrical signals are used to tell the flight control servos where to position the control surface (by supplying hydraulic fluid to the actuators) rather than controls cables. So FBW nothing to do with the incident.

Am I missing something??????

Just for the record, THERE IS NO MANUAL REVERSION on the 777. By manual reversion I am talking about what exists on the 737/727. There is a manual backup very similar to the 320, but it's not manual reversion


User currently offlineEx52tech From United States of America, joined Dec 2006, 559 posts, RR: 1
Reply 20, posted (6 years 2 months 6 days 1 hour ago) and read 4112 times:



Quoting Starlionblue (Reply 11):
It would not have been in an unknown state. Direct Law is only used if you lose quite a few control systems and power systems

My question here is .........Is the A330 being powered by the APU, which would have allowed for the hydraulics to be powered by the electric pumps, or are we on just the emergency bus here?
How does the protection system work on just battery power? I do not recall if that situation came up when I went to A320 school many years ago.



"Saddest thing I ever witnessed....an airplane being scrapped"
User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 21, posted (6 years 2 months 6 days 1 hour ago) and read 4100 times:



Quoting PhilSquares (Reply 19):
There is a manual backup very similar to the 320, but it's not manual reversion

What I want to know is how the "manual back up works". How is the servo actuated in the manual back-up mode, are there cables? From what I have read the 777 has three separate channels in the flight control system which, did away with the requirement for a mechanical back-up. Is this wrong?


User currently offlineStarlionblue From Greenland, joined Feb 2004, 16908 posts, RR: 67
Reply 22, posted (6 years 2 months 6 days ago) and read 4095 times:



Quoting Zeke (Reply 18):
Quoting Starlionblue (Reply 11):
It would not have been in an unknown state. Direct Law is only used if you lose quite a few control systems and power systems. Assuming the engines were the only affected system, the aircraft would have remained in Normal Law.

It is not an unknown state with all engines failed, with an all engine flame out you are in direct law because of the loss of electrical buses and hydraulics, the FBW protections are not in place, Airbus has a QRH procedure for this (unlike the 777). With engines still developing thrust as it appears in this accident, a A330 in a similar case would still be in normal law as the electrics and hydraulics are normally powered.

Indeed as you say the "engines out" and the "engines idling" scenarios are quite different. AFAIK BA038 had engines idling, so in an equivalent 330 it would have been normal law unless I'm much mistaken.

Quoting 474218 (Reply 13):
Quoting Starlionblue (Reply 11):
It would not have been in an unknown state. Direct Law is only used if you lose quite a few control systems and power systems. Assuming the engines were the only affected system, the aircraft would have remained in Normal Law.

There is nothing "Normal" about loosing forward thrust when the wing is as dirty as BA038's.

It's called "Normal Law". I didn't invent the name. It is not a reference to flight circumstances. It is a mode of the Airbus flight control systems.

Quoting BuyantUkhaa (Reply 17):

Quoting Starlionblue (Reply 6):
t is not the case of a French computer suddenly intoning (cue French movie villain voice): "I don't wanna talk to you no more, you empty headed animal food trough wiper! I fart in your general direction! Your mother was a hamster and your father smelt of elderberries!"

What a strange person!

Did you not watch "Monty Python's Quest for the Holy Grail"?!? If you haven't, you owe it to yourself to go rent or buy it and have a nice evening of hysterical laughter. Big grin KELPkid's comment is in reference to the same scene.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 23, posted (6 years 2 months 5 days 22 hours ago) and read 4071 times:



Quoting Zeke (Reply 18):
Because of the envelope protection that is on the Airbus, it has a lower stall buffet than similar aircraft, it is one of the reasons why the Airbus FBW outperforms the Boeing FBW on maneuvers like a CFIT recovery.

Are you sure about that? On the Airbus you get Alpha Prot at a AOA less than the stall AOA. However, on the 777 you can pull up to the max energy line and be right on the stick shaker. That is where the wing is being max performed. My understanding was on Airbus you could never get there. In a situation as you described, CFIT, the Boeing would give a little bit better AOA.


User currently offlineMandala499 From Indonesia, joined Aug 2001, 6590 posts, RR: 75
Reply 24, posted (6 years 2 months 5 days 22 hours ago) and read 4058 times:



Quoting DH106 (Reply 2):
Yes, but as I understand it Airbus has a 'hard' envelope protection whilst Boeing allows pilots the final say - exceeding the envelope if commanded. Assuming similar glide ratios it boils down to:

Yes but as Roseflyer wrote...

Quoting RoseFlyer (Reply 12):
It takes about 70lbs of back pressure to make a 777 stall. The computer will let you do it, but you have to put a lot of work into stalling a 777.

And according to a friend who flies the 777... "you can tell the computer to buzz off, but you do that by having a fight against it!"  Smile

Quoting Dw747400 (Reply 15):
I know a 777 has to spoilers hooked up for non-FBW roll control, and I think either the elevator or the elevator trim can be manually actuated as well.



Quoting PhilSquares (Reply 19):
Just for the record, THERE IS NO MANUAL REVERSION on the 777. By manual reversion I am talking about what exists on the 737/727. There is a manual backup very similar to the 320, but it's not manual reversion

I agree that it isn't manual reversion, it's a manual back up... ie: you can't select it, it gets selected when everything else screws up... Manual reversion I think you can select it or induce it (I wouldn't bother unless I'm a test pilot getting bored with my career).

If I was informed correctly, for the 777 it's roll by spoilers or differential thrust and pitch by trim (the electric switches on the yoke, or the STAB TRIM tab on the pedestal... no elevator no rudder... On the bus, again if I was informed correctly, it's rudder, trim wheel and thrust...

It does sound like the Bus manual back up require more than a handful, but then again, I haven't read the manuals on those sections for those aircraft.

Mandala499



When losing situational awareness, pray Cumulus Granitus isn't nearby !
25 Zeke : Compare the two CFIT recovery procedures, the Airbus is full back stick to go to Alfa Max (with auto speed brake retraction), on the 777 you pitch at
26 Jetlagged : Stick shaker does not occur at Clmax. So in flying on the shaker you are not at maximum lift. Airbus is similar, you climb at what is effectively sti
27 SEPilot : When is Direct Law invoked? Does the pilot select it or is it automatically selected under certain circumstances. If so, when?
28 OldAeroGuy : It's not quite pulling with all your might. The current 777 Chief Pilot is female and weighs about 55 kg. She has been able to stall the 777 quite re
29 DH106 : Twas me you actually quotede Zeke - not Motopolitico Yes, but as Zeke has alluded to with his CFIT explanation - you're not looking for max AOA/CL (m
30 474218 : That is just as I though, no manual revision, thanks OldAeroGuy.
31 OldAeroGuy : The 777 QRH's I've seen have an All Engines Inoperative set of procedures. Maybe you were looking at a version your airline had edited.
32 Zeke : All of our manuals are tailored, but I would not think we would remove that. Can you let me know the exact title, I have access to the manuals from a
33 Post contains images Jetlagged : The MD80 flight controls are manual all the time! Manual reversion on a 777 sized aircraft would be very difficult to arrange, FBW or not. The 747 is
34 Post contains links OldAeroGuy : Then why is there a hydraulic line running to the elevators? http://www.md80.it/OLDFILES/schemi/FlightControls/two.JPG The MD80 and the 737 use hydra
35 DH106 : I think the MD-80 has an emergency stall recovery push-down elevator function, which is probably what the hydraulic line is for. Normally the elevato
36 SEPilot : Thanks for the explanation.
37 Post contains links Jetlagged : Correct. This thread describes it all in detail: MD-80 Elevator Controls (by TWAMD-80 Jul 12 2003 in Tech Ops)
38 OldAeroGuy : Thanks for correcting my mis-understanding. I thought the 737 and DC9/MD80 flight control systems were similar since they are of the same airplane de
39 OldAeroGuy : Don't have a copy of the QRH at hand, but you might try "Dual Engine Failure".
40 BAe146QT : From what we have been told, that's what the FO did anyway. So the answer might be, "The same outcome would probably have occurred in the Airbus. The
41 DH106 : Lot of 'if's there. Why wouldn't the pilot of the A330 also lower the nose in the same situation? The computers would only do so to prevent an immine
42 Post contains images Litz : Only if catapulted by guys in medieval armor, with British accents ... We'd have probably felt the earth shake on this side of the pond, in that case
43 Starlionblue : Yeah. The pilot would have behaved the same way, but the plane would have been there to catch a stall if needed. Of course a well trained pilot won't
44 OldAeroGuy : I thought the cow was catapulted by guys with French accents. Since Airbus FBW won't allow you to fly past stall warning speeds and Boeing FBW will,
45 Post contains images Starlionblue : Fair point. So it's all still pretty academic.
46 DH106 : I believe the report is published by the British AAIB, not AARB. Didn't the captain take the flaps in a notch - to reduce the 'drag flap' when he rea
47 Jetlagged : Below 100 feet RA the Airbus is in a form of direct law anyway so presumably could have been stalled in over the last few feet, just as the 777 appea
48 Post contains images BAe146QT : Thanks all who picked up my question and analysed/answered it. Please understand that I asked the question not because I have a prejudice one way or t
49 Longhornmaniac : My dear friend, you must have missed the rest of his post... A WITCH!!!!!!!!!!!! This has been a really interesting read... Cheers, Cameron
50 Post contains images KELPkid : But it would have to float first...
51 Starlionblue : Yes I did. I blame jetlag. Not that I've flown anywhere in 5 months. But I still blame it!!!
52 Motopolitico : Well, thanks one and all for entertaining my foolish question. I knew I wouldn't be able to ask this in civil aviation without it degenerating into a
53 Post contains images BuyantUkhaa : I saw your post only now - "what a strange person!" is King Arthur's reaction to zee French.
54 Starlionblue : Sorry again. ***embarrassed***
55 Post contains links OldAeroGuy : Not mentioned in the AAIB (note corrected alphabetology) report. http://www.aaib.dft.gov.uk/publicati...08___boeing_777_236_er__g_ymmm.cfm It says th
56 DH106 : Well - at 1.04Vs(1g) you'll almost certainly be on the back side of the drag curve, so allowing the airplane slow to 1.01Vs(1g) would actually shorte
57 OldAeroGuy : Only if you immediately go to 1.01Vs. From a purely static case, the best glide distance would be achieved by holding best L/D speed (near 1.23 Vs fo
58 DH106 : Yes - fair enough: IF the AirBus has Normal Law down to the ground, the 777 has a small advantage in being able to flair slightly longer with a skill
59 Zeke : Sorry, I just dont that is possible on the 777 or any airliner for that matter. The amount of control force required, and the precision required to g
60 DH106 : Didn't realise there was a video. Do you have a link Zeke?
61 OldAeroGuy : Which is why I said what I did in Reply 28. The real vs the theoretical tends to cloud the whole Airbus FBW vs Boeing FBW discussion. However, the di
62 Zeke : It was linked on one of the previous threads in CivAv, only it was only short. You are talking about relative angles of attack seen by the wing, I wa
63 OldAeroGuy : But you don't want to slow from 1.23Vs until near the ground and then perform a flare . During the flare, the vertical velocity is decreasing and the
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