777 FLCH getting stall protection
Thread Starter
Joined: Nov 2004
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From: Here, there, and everywhere
777 FLCH getting stall protection
Along with some other modes.....
Older planes in fleet......
Note: The autothrottle will not automatically activate to support stall protection when the pitch mode is FLCH SPD or TO/GA.
Note: The autothrottle will not support stall protection when the A/T mode is HOLD.
Note: During a descent in VNAV SPD with the autothrottle armed and not active, the autothrottle can automatically activate in HOLD mode and will not advance thrust levers to support stall protection.
Newer planes in fleet.....
If the pitch mode is FLCH SPD, VNAV SPD, or VNAV PTH and A/T is in HOLD or THR mode, and speed decreases into the amber band, the A/T will change from HOLD to THR mode. Thrust will increase proportional to amount speed has decreased into the amber band.
If the pitch mode is TOGA during takeoff, and the A/T is in HOLD mode, and thrust has been manually set below the TO thrust reference, and a low speed condition is encountered, then the A/T mode will change from HOLD to THR REF and will advance thrust towards the selected TO thrust reference while airspeed is within 10 kts of stick shaker speed.
Note: During a descent in VNAV SPD or FLCH SPD with the autothrottle armed and not active, the autothrottle automatically activates in THR mode and advances thrust to a throttle position corresponding to the relative distance speed has decreased into the amber band so that if speed continues to decrease, thrust will reach the CLB thrust limit as stick shaker is activated.
Older planes in fleet......
Note: The autothrottle will not automatically activate to support stall protection when the pitch mode is FLCH SPD or TO/GA.
Note: The autothrottle will not support stall protection when the A/T mode is HOLD.
Note: During a descent in VNAV SPD with the autothrottle armed and not active, the autothrottle can automatically activate in HOLD mode and will not advance thrust levers to support stall protection.
Newer planes in fleet.....
If the pitch mode is FLCH SPD, VNAV SPD, or VNAV PTH and A/T is in HOLD or THR mode, and speed decreases into the amber band, the A/T will change from HOLD to THR mode. Thrust will increase proportional to amount speed has decreased into the amber band.
If the pitch mode is TOGA during takeoff, and the A/T is in HOLD mode, and thrust has been manually set below the TO thrust reference, and a low speed condition is encountered, then the A/T mode will change from HOLD to THR REF and will advance thrust towards the selected TO thrust reference while airspeed is within 10 kts of stick shaker speed.
Note: During a descent in VNAV SPD or FLCH SPD with the autothrottle armed and not active, the autothrottle automatically activates in THR mode and advances thrust to a throttle position corresponding to the relative distance speed has decreased into the amber band so that if speed continues to decrease, thrust will reach the CLB thrust limit as stick shaker is activated.
Joined: Mar 2006
Posts: 1,115
Likes: 86
From: England
So is this a Boeing admission that this feature contributed to accidents or incidents ?
A positive view is ‘well done’ Boeing for improving a weak system to enhance safety.
The tacit recognition of the difficulties arising from human factors and the need to change system design opposed to ‘retrain’ pilots.
A positive view is ‘well done’ Boeing for improving a weak system to enhance safety.
The tacit recognition of the difficulties arising from human factors and the need to change system design opposed to ‘retrain’ pilots.
Joined: Mar 2006
Posts: 2,633
Likes: 137
From: USA
So is this a Boeing admission that this feature contributed to accidents or incidents ?
A positive view is ‘well done’ Boeing for improving a weak system to enhance safety.
The tacit recognition of the difficulties arising from human factors and the need to change system design opposed to ‘retrain’ pilots.
A positive view is ‘well done’ Boeing for improving a weak system to enhance safety.
The tacit recognition of the difficulties arising from human factors and the need to change system design opposed to ‘retrain’ pilots.
Joined: Mar 2002
Aviation Qualifications: ATPL
Posts: 9,226
Likes: 994
From: Seat 1A
The tacit recognition of the difficulties arising from human factors and the need to change system design opposed to ‘retrain’ pilots.
Maui, suck it up!
Joined: Jan 2004
Posts: 3,246
Likes: 202
From: Here and there
I believe constant descent is an option. Unfortunately our company doesn’t have it. I agree that the way managed DES flies level segments before and during approaches is ridiculous, along with the coding that puts the decel waypoint AT the level off point instead of slightly before, resulting in a burst of thrust during level off unless the pilot intervenes. It is a system designed by engineers with no thought on how to operate with finesse.
Joined: Jul 2009
Aviation Qualifications: Spotter
Posts: 241
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From: Coast to Coast...
Any one of you actually flown a 787 VNAV descent? (I admit not having flown a 777, maybe that is better than the 787). The 787 one is !!!!e probably because it's a straight port of the 777 one. I.e. Boeing, in what now appears to be a habit, has failed to update the logic which tells VNAV that the 787 is a much more slippery aircraft. This is basic, absolute BASIC QA and in over 5 years of operation, Boeing have not dealt with the issue despite it being reported by numerous airlines. Says a lot really.
Last edited by Smooth Airperator; 2nd May 2019 at 15:29.
Joined: Mar 2006
Posts: 2,633
Likes: 137
From: USA
As to the FINAL APP logic, yes, it's stupid with the level segments. I read on the Honeywell or Thales site that the A330 fmc has an update where it will fly a constant descent using the geometric path used for the rest of the descent. They don't seem to be interested in putting that in the 320 though.
Joined: Sep 2011
Posts: 352
Likes: 148
From: FL390
Any one of you actually flown a 787 VNAV descent? (I admit not having flown a 777, maybe that is better than the 787). The 787 one is !!!!e probably because it's a straight port of the 777 one. I.e. Boeing, in what now appears to be a habit, has failed to update the logic which tells VNAV that the 787 is a much more slippery aircraft.
Joined: Nov 2007
Posts: 44
Likes: 3
From: London
I have taken to starting the stopwatch at top of drop and accepting bets on how long before we get the drag required message. Often it’s less than two minutes. Some clever F/Os I fly with alter the anti-ice on altitude in the descent winds page of the FMC which allegedly helps but I haven’t worked out how that actually works. Sorry for he thread drift
Thread Starter
Joined: Nov 2004
Posts: 1,324
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From: Here, there, and everywhere
Joined: Mar 2001
Posts: 4,563
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From: I wouldn't know.
As to the FINAL APP logic, yes, it's stupid with the level segments. I read on the Honeywell or Thales site that the A330 fmc has an update where it will fly a constant descent using the geometric path used for the rest of the descent. They don't seem to be interested in putting that in the 320 though.
Joined: Mar 2006
Posts: 2,633
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From: USA
Joined: Oct 2013
Posts: 380
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From: Wengen
Options Must Be Standard!
Not speaking specifically about stall protection. Airbus does a pretty good job at that. As much as I like the plane, I still feel that the uncoupled sidesticks and stationary thrust levers are design flaws. Granted, that's harder to fix than the FLCH logic on the 777. Unfortunately, if they didn't admit that after AF447, they probably never will.
As to the FINAL APP logic, yes, it's stupid with the level segments. I read on the Honeywell or Thales site that the A330 fmc has an update where it will fly a constant descent using the geometric path used for the rest of the descent. They don't seem to be interested in putting that in the 320 though.
As to the FINAL APP logic, yes, it's stupid with the level segments. I read on the Honeywell or Thales site that the A330 fmc has an update where it will fly a constant descent using the geometric path used for the rest of the descent. They don't seem to be interested in putting that in the 320 though.
I am sure that airlines and manufacturers in the wake of the Max tragedies will rethink their "Profits Foremost, Savings First, Safety Last" policy.
It is an absolute scandal that contrived "options" are tantamount to safety being optional.
