Go Back  PPRuNe Forums > Flight Deck Forums > Rumours & News
Reload this Page >

Air France B777 control issues landing CDG

Rumours & News Reporting Points that may affect our jobs or lives as professional pilots. Also, items that may be of interest to professional pilots.

Air France B777 control issues landing CDG

Old 26th Apr 2022, 23:57
  #121 (permalink)  
 
Join Date: Sep 2004
Location: Yorkshire
Posts: 597
Likes: 0
Received 3 Likes on 2 Posts
From the examples above:-
Weak auto thrust design, the system could go to sleep; the designer was surprised.
Weak FD switching logic, mandated use of FD for takeoff; the operator was surprised.
Multiple probe icing beyond the conditions assumed by regulation; the regulator was surprised
Okay, the above anomalies occurred, but the in each case the aircrew made some woeful errors that actually caused the accident/incident:
- No attempt to monitor the airspeed during the approach into SFO
- Blindly following the FD during take-off without looking out of the window (or again, monitoring their airspeed!)
- Continuing to maintain a pitch-up input despite the obvious clues!
H Peacock is offline  
Old 27th Apr 2022, 08:52
  #122 (permalink)  
 
Join Date: Jul 2003
Location: An Island Province
Posts: 1,226
Likes: 0
Received 0 Likes on 0 Posts
The adverse human view continues, ‘aircrew’, … ‘error’ - a definition after the fact.
Similarly human activities, ‘monitor’, ‘blindly following’, ‘continuing to maintain’, describe what is assumed to have occurred, but for which we have insufficient knowledge about the crews were thinking, nor their reasoning of the choice of activity / inactivity.

The important question is if it is reasonable to expect crews to manage these situations, considering the nature or rarity of the anomaly, the operational pressures, and crew’s training and experience.
40 yrs ago safety was defined by outcome, body count. Nowadays, still based on outcome, much safer, but we fret over mistaken button pushes, the finesse of flight control and judgement calls, in very safe but vastly more complicated aircraft flown in complex situations.

This incident had a safe outcome; how was that accomplished, compare that activity with the vast number of normal operations. Then and only then consider the specific activities which we judge adverse, what is assumed, taken for granted.
The investigation into this event could help with these questions, but even so, our biased selves with hindsight will conclude what ever we wish; what we choose to learn.
alf5071h is offline  
Old 27th Apr 2022, 18:22
  #123 (permalink)  
 
Join Date: Apr 2008
Location: London
Posts: 195
Likes: 0
Received 0 Likes on 0 Posts
The BEA have issued a report


Lord Bracken is offline  
Old 27th Apr 2022, 19:31
  #124 (permalink)  
 
Join Date: Sep 2012
Location: Europe
Posts: 211
Likes: 0
Received 0 Likes on 0 Posts
So if I am reading this right, the copilot was surprised by his actions having the exact consequences you'd expect, given this collection of input/output data? Eg. mostly left roll input, airplane banks left.
Or did he maybe expect higher roll rate from the aircraft for his inputs? I know this is just a preliminary report/investigation update, but seems like there was not much wrong with the aircraft.

About the fact that they did not notice their conflicting inputs... I do not fly the type, so excuse my lack of knowledge on the exact flight control config on the 777. But is it not supposed to be one of the upsides of Boeings FBW philosophy, to keep the yokes still moving in sync and provide feedback?
Intrance is offline  
Old 27th Apr 2022, 20:53
  #125 (permalink)  
 
Join Date: Aug 1998
Location: the ridge where the west commences
Posts: 760
Likes: 0
Received 0 Likes on 0 Posts
So....nothing wrong with the airplane other than that the two people sitting farthest forward were not competent and disciplined pilots.

Quelle surprise.
Dropp the Pilot is offline  
Old 27th Apr 2022, 21:14
  #126 (permalink)  
 
Join Date: Jul 2013
Location: Everett, WA
Age: 67
Posts: 3,806
Received 7 Likes on 6 Posts
Originally Posted by Intrance View Post
About the fact that they did not notice their conflicting inputs... I do not fly the type, so excuse my lack of knowledge on the exact flight control config on the 777. But is it not supposed to be one of the upsides of Boeings FBW philosophy, to keep the yokes still moving in sync and provide feedback?
Yes, the control wheels are physically interconnected so that whatever one wheel does, the other does.
There is a 'breakout' feature that can disconnect the two should one get jammed, but it takes considerable force to trigger that 'breakout' and it certainly doesn't look like it came into play in this incident.
tdracer is offline  
Old 27th Apr 2022, 21:47
  #127 (permalink)  
zzz
 
Join Date: Mar 1999
Location: N/A
Posts: 64
Likes: 0
Received 0 Likes on 0 Posts
It seems like both pilots made control inputs simultaneously but there doesn’t sound like a break out of the control columns happened; that requires a lot of force.
Why was the FO confused about the bank? He was hand flying in cloud. Did he become disorientated and/or have “the leans”?
zzz is offline  
Old 27th Apr 2022, 21:47
  #128 (permalink)  

Only half a speed-brake
 
Join Date: Apr 2003
Location: Not commuting home
Age: 45
Posts: 4,117
Received 2 Likes on 2 Posts
The BEA press release clearly spells the flight column channels had been temporarily de-synchronized due to opposing forces on the yoke. Also, note "8" explains what that means and the 50 lbs force required. Parlez vous Twitter?

How that works or manifests IRL would be great to hear if someone has the knowledge or experience to share.
FlightDetent is online now  
Old 27th Apr 2022, 22:18
  #129 (permalink)  
 
Join Date: Nov 2000
Location: UK
Age: 67
Posts: 1,332
Received 1 Like on 1 Post
FFS "I have control" end of. But then the French have an inordinate love of the third person indefinite.
On est un con.
beardy is offline  
Old 27th Apr 2022, 23:54
  #130 (permalink)  
 
Join Date: Sep 2012
Location: Europe
Posts: 211
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by tdracer View Post
Yes, the control wheels are physically interconnected so that whatever one wheel does, the other does.
There is a 'breakout' feature that can disconnect the two should one get jammed, but it takes considerable force to trigger that 'breakout' and it certainly doesn't look like it came into play in this incident.
OK, that is what I expected. Slightly odd to not have noticed those 'de-sync' or breakout moments, though I can see it possibly being missed or forgotten about in a high stress/high workload situation. And it kind of seems like the pilot flying caused such a situation with the pilot monitoring trying to understand what was going on and failing to intervene properly.

I think this investigation and its results will be pretty interesting reading, though possibly not very flattering for the pilots...
Intrance is offline  
Old 28th Apr 2022, 00:36
  #131 (permalink)  
 
Join Date: Jul 2013
Location: Everett, WA
Age: 67
Posts: 3,806
Received 7 Likes on 6 Posts
Originally Posted by FlightDetent View Post
The BEA press release clearly spells the flight column channels had been temporarily de-synchronized due to opposing forces on the yoke. Also, note "8" explains what that means and the 50 lbs force required. Parlez vous Twitter?
If they activated the breakout (surprising - the normal loads on the 777 control wheels are pretty light as long as you're not doing something stupid like pulling into a stall - to have to apply greater than 50 lbs. on the wheel should have been a dead giveaway that the pilots were working against each other), I'm reasonably sure it takes a maintenance action to reconnect them (I'm thinking it's a frangible link but I'm not sure about that). So that would explain the aircraft being grounded for a few days after the event.
tdracer is offline  
Old 28th Apr 2022, 01:51
  #132 (permalink)  
 
Join Date: Mar 2016
Location: UK
Posts: 68
Likes: 0
Received 0 Likes on 0 Posts
Ignoring the initial confusion and left roll by the PF. Seems like the pilots conception of the aircraft not responding to commands as expected could be due to them fighting each other without realising it and believing they are fighting the aircraft? They then apply this mental model retroactively to the initial event?
am111 is offline  
Old 28th Apr 2022, 03:53
  #133 (permalink)  
 
Join Date: Mar 2002
Location: Above and beyond
Posts: 1,060
Received 22 Likes on 15 Posts
Originally Posted by tdracer View Post
If they activated the breakout (surprising - the normal loads on the 777 control wheels are pretty light as long as you're not doing something stupid like pulling into a stall - to have to apply greater than 50 lbs. on the wheel should have been a dead giveaway that the pilots were working against each other), I'm reasonably sure it takes a maintenance action to reconnect them (I'm thinking it's a frangible link but I'm not sure about that). So that would explain the aircraft being grounded for a few days after the event.
The control column breakout mechanism is a cam and roller mechanism, held together by springs. The flight parameters in the report show the control columns were ‘desynchronised’ for about 15 seconds. After that, they again moved in unison. The control wheel jam breakout mechanism has two force limiters and two lost motion devices that allow the other control wheel to continue roll control if one of the control wheels jams. The flight parameters show the control wheels were desynchronised for two brief periods of 2 seconds and 5 seconds duration during the same period the control columns were desynchronised.

The force required to override either breakout mechanism is 50 lb.

Last edited by BuzzBox; 28th Apr 2022 at 13:14. Reason: Updated with details of the control column and control wheel breakout mechanisms.
BuzzBox is online now  
Old 28th Apr 2022, 04:50
  #134 (permalink)  
 
Join Date: May 2008
Location: us
Posts: 17
Likes: 0
Received 0 Likes on 0 Posts
Yet another wrestling match at AF.

Perhaps it"s their actual procedure ..... best man wins.
runner1021 is offline  
Old 28th Apr 2022, 06:27
  #135 (permalink)  
Pegase Driver
 
Join Date: May 1997
Location: Europe
Age: 72
Posts: 3,278
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by runner1021 View Post
Yet another wrestling match at AF.
Perhaps it"s their actual procedure ..... best man wins.
Good one , Indeed not a good day for them again. The BEA does not make any remark on the rest / fatigue status of the pilots which is one of the main rumors around CDG . But that might come with the full report, although, based on their previous publications, I am not sure the BEA will go too deeply into it..
ATC Watcher is offline  
Old 28th Apr 2022, 06:52
  #136 (permalink)  
 
Join Date: Mar 2002
Location: Above and beyond
Posts: 1,060
Received 22 Likes on 15 Posts
Originally Posted by ATC Watcher View Post
Good one , Indeed not a good day for them again. The BEA does not make any remark on the rest / fatigue status of the pilots which is one of the main rumors around CDG . But that might come with the full report, although, based on their previous publications, I am not sure the BEA will go too deeply into it..
Recency is another factor they should consider, given the reduced flying rate for most pilots during COVID.
BuzzBox is online now  
Old 28th Apr 2022, 11:28
  #137 (permalink)  

Only half a speed-brake
 
Join Date: Apr 2003
Location: Not commuting home
Age: 45
Posts: 4,117
Received 2 Likes on 2 Posts
Originally Posted by BuzzBox View Post
The control columns were ‘desynchronised’ for about 15 seconds. After that, they again moved in unison.
And desynchronised twice again momentarily. Revealing 50 lbs of opposing force - unless the mechanism was misadjusted soft (speculation, don't even know how it works) and uncoupled too easily.

The idea that on a Boeing you can't feel with your steering what the other person is doing or overpower him is a novelty in many circles, mine included.

​​​​
FlightDetent is online now  
Old 28th Apr 2022, 11:30
  #138 (permalink)  

Only half a speed-brake
 
Join Date: Apr 2003
Location: Not commuting home
Age: 45
Posts: 4,117
Received 2 Likes on 2 Posts

FlightDetent is online now  
Old 28th Apr 2022, 12:17
  #139 (permalink)  
 
Join Date: Apr 2018
Location: Sudbury, Suffolk
Posts: 219
Likes: 0
Received 0 Likes on 0 Posts
It appears that the BEA are just as puzzled by
a) desynchronised control inputs and
b) the inability of the crew to recognise them
as this forum is.
Maninthebar is online now  
Old 28th Apr 2022, 12:34
  #140 (permalink)  
 
Join Date: Jan 2015
Location: Centre of Universe
Posts: 346
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by BuzzBox View Post
Recency is another factor they should consider, given the reduced flying rate for most pilots during COVID.
So recency is an issue and ATC watcher is saying fatigue played a hand. If its recency then its sleepiness (the need for sleep) rather than fatigue. There is a subtle difference ATC Watcher
Twiglet1 is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell or Share My Personal Information

Copyright © 2023 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.