737 Classic Reject or Continue?

[Rainboe]

The abort parameters are very strictly laid down, both for the sub-80kt case and the over-80kt/belowV1 case. It always bemuses me the number of people who come up with 'but I would do this if it happened'. I suppose they like being part of the accident statistics for discussion in Pprune! If the parameters are strictly laid down by companies with the bark of Boeing and presumably Airbus, who are these pilots that reckon they know better, and why do they think they are safe enough to fly passengers?

I see Post 2 of 'Abort Abort Abort!' has, not surprisingly, been removed.

[NonFlushingLav]

Corporate jet crashed due to two buckets opening up on take off...evidentely they had been locked out by maintanance, then closed. Pilot hopped in, took off, crashed. TR light for me, is an instant abort prior to V1...simply put, hitting the stow button might not work. In the sim a double TR deployment acts stupid, unrealistic, I think it can be flown with enough speed...but at lower speeds, trying to acclerate and fly out with all that drag prior to V1 is suicide in my opinion.

[PantLoad]

Airbus FCOM (A320 Series) Inclusive of REV 42

Gentlemen:

With regard to rejected takeoffs, Airbus has this to say:
-----------------------------------------------------------------------
ABOVE 100 KNOTS AND BELOW V1:

Rejecting the takeoff at these speeds is a more serious matter, particularly on slippery runways. It could lead to a hazardous situation, if the speed is approaching V1. At these speeds the captain should be "go- minded" and very few situations should lead to the decision to reject the takeoff:

1. Fire warning or severe damage.
2. Sudden loss of engine thrust.
3. Malfunctions or conditions that give unambiguous indications that the aircraft will not fly safely.
4. Any red ECAM warning.
5. Any amber ECAM caution listed below:
. F/CTL SIDESTICK FAULT
. ENG FAIL
. ENG REVERSER FAULT
. ENG REVERSE UNLOCKED

Exceeding the EGT red line or nose gear vibration should not result in the decision to reject the takeoff above 100 knots.

In case of tire failure bewteen V! minus 20 knots and V1:
Unless debris from the tires has caused serious engine anomalies, it is far better to get airborne, reduce the fuel load load, and land with the full runway available.

The V1 call has precedence over any other call.
-----------------------------------------------------------------------


Boeing may be different...it's been many years since I flew a Boeing, so I can't tell you what they say. But, this is the Airbus philosophy.


Fly safe,


PantLoad

[Rainboe]

Interesting. Slightly different philosophy, but not significantly different.

[Mach E Avelli]

In my view, not knowing whether the reverser has really unlocked or could unlock at any time falls into the 'it's better to be on the ground wishing you were up there, than being up there wishing you were on the ground' category. Having read all about the Lauda crash, I would reject up to V1 and cop the criticism from the armchair experts even if it did turn out to be nothing more than a faulty sensor.

[NonFlushingLav]

Mach E Velli +1 Couldn't have said it better...everyone on the ground alive, vs yet another pilot who thought he could fly the plane off to the scene of the accident. Yeah I will take a little flack from the Monday morning quaterbacks if the passengers are alive.

[SNS3Guppy]

You'd be copping a lot more than criticism if you rejected only to find you'd damaged the airplane...which is a big part of the reason that Boeing states one should NOT reject for a T/R indication in absence of vibration, directional control issues, or other indications that it's more than just a light.

Bear in mind that with the Lauda mishap, the airplane had already experienced 13 incidents of recorded T/R failures and failure messages in the months preceeding the crash. The crew had warnings for about ten minutes before the reverser deployed. Further, the event which occured where the subject of multiple later system changes and airworthiness directives...this isn't something to be expected or reasonably anticipated on other aircraft, or the same aircraft in the time since.

If you place the flight in jeopardy over what you think might happen, you accept a real risk and a high probability of damage, vs. a possibility which does not yet exist. When considering abnormalities or emergencies occuring during the high speed portion of the takeoff roll, in nearly all cases you are FAR better to continue the takeoff and treat the condition as an airborne emergency.

Whereas the engine may be shut down in very sort order, the threat of a T/R deployment isn't worthy of a high speed rejected takeoff if no other conditions exist at the time of the reverser indication.

If you want to compare the 767 mishap with the question central to the thread about identifying a problem a few knots before V1, you have to take into account the ten minutes the crew had to consider the abnormality announcement. Furthermore, the crew wasn't looking at an unlocked or T/R deployment condition immediately, but the same valve annunciations that had been occuring in the past; there's more history to what happened than simply someone saw a light and took action (or didn't).

[lomapaseo]

It sounds to me like a good idea to follow the recommended procedure for your specific aircraft. If life would be simpler to have a consistent procedure accross both Boeing and Airbus aircraft than just ask them for a rationale through your safety representative.

[A37575]

and a roll mode is selected

What on earth has a roll mode got to do with it? You have got ailerons - use them and forget about a god almighty rush to get the autoflight systems engaged. Flight directors are there as an aid - not the be all and end all of navigating the beast.

[Centaurus]

During Toff roll say 10 to 5 Kts. prior to V1, the Reverser Unlocked light of one engine pops up

If the thrust lever retards automatically then you are in reverse on that engine and you reject fast. If there is no movement of the thrust lever then you are in forward thrust and you continue. Sort the problem light when you get time. Any abort that close to a real V1 on a limiting runway length - especially if a wet runway, is asking for trouble. Sometimes you have to make a critical decision and wear it.

[Rainboe]

What on earth has a roll mode got to do with it? You have got ailerons - use them and forget about a god almighty rush to get the autoflight systems engaged. Flight directors are there as an aid - not the be all and end all of navigating the beast.

I'm afraid things have changed on the more modern aeroplanes! It is standard now with any defect you carry into the air to get the aeroplane settled in teh climb, gear up, and at 400' select a roll mode- Hdg or LNav as required. if you have an engine out, you are not allowed to turn, you must climb straight ahead unless specifically req'd on that runway to do otherwise. Contravene that and you look for another job.

Mach E Avelli:

In my view, not knowing whether the reverser has really unlocked or could unlock at any time falls into the 'it's better to be on the ground wishing you were up there, than being up there wishing you were on the ground' category.

Ignore your training and you will be looking for another job! You get trained, then come a problem and you throw it away and decide you know better than Mr. Boeing? How many Boeing aeroplanes have crashed with full reverse on take-off? Zero. How many Boeing aeroplanes have had false 'reverser unlocked' warning lights on take-off? Quite a few I would hazard a guess- I have had false reverse indications, but not on take-off. Boeing recommend that particular take-off briefing I outlined earlier. Why throw that away the first time you have (what you think is) an emergency? Foolhardy to abandon near V1 for a stupid false warning light! Wake up guys and reread your emergency briefing! Then for goodness sake stick to it! You do not know better!

Mach E Avelli- you aren't a prof pilot, are you? Have you been Boeing trained? If not, why are you involving yourself in this discussion without saying so? Do you think passing your opinion is advisable in a discussion of this nature?
'

[galdian]

Rainboe

Actually (at least on the NG) Boeing DOES allow (albeit implied, not explicit) a reject for something such as T/R:

The criteria in my company's manuals:
- engine fail
- engine fire
- predictive windshear
- if the aircraft is insafe, or unable, to fly.

Suspect T/R deployed would comfortably fit the last, of course more than happy for the techies to provide how successfully an aircraft will take-off and climb (or not) with a T/R deployed.

Would be interesting to ask those who have been there (maybe the Lauda boys??) what a real T/R deployment does to an aircraft - oops, sorry, they're too busy looking for another job.

Call me crazy but I go to work each day not worrying about whether I'll need to start looking for another job tomorrow but hoping to marry my training with a fair amount of commonsense regards what's happening around me in the real environment, not a simulator solely or the thoughts of the multitudes on Pprune and similar.

Partly to safeguard the aircraft and all the souls within, mainly to minimise all those pesky "reports to the company" you have to write when things don't quite line up as expected.

Cheers.

[SNS3Guppy]

Suspect T/R deployed would comfortably fit the last, of course more than happy for the techies to provide how successfully an aircraft will take-off and climb (or not) with a T/R deployed.

Have you looked at the procedure for inadvertant reverse thrust in flight?

A T/R light isn't a suspected T/R deployed. Not without secondary indications such as directional control issues, buffeting, vibration, etc. Further, if you're comparing the 767 to your 737, especially the 767 prior to introduction of the T/R AD's, then you're making an inappropriate comparison.

The criteria in my company's manuals:
- engine fail
- engine fire
- predictive windshear
- if the aircraft is insafe, or unable, to fly.

Is a T/R unlock light an engine failure? No.

Is a T/R unlock light an engine fire? No.

Is a T/R unlock light a predictive windshear warning? No.

Is a T/R unlock light an unsafe condition that makes the airplane unable to fly? Not according to Boeing.

By applying your own spin or interpretation, rather than the manufacturer, you risk making a high speed rejected takeoff and putting the flight in certain danger, rather than a perceived danger which does not exist...in other words, you're putting the flight in harms way...not avoiding a dangerous situation. When you see that light and it's not accompanied by movement of the thrust lever or by secondary (and obvious) indications that the T/R really is deployed, then you're creating a dangerous condition when one doesn't yet exist...in other words, there isn't a problem until you elect to make one by rejecting the takeoff unnecessarily.

[galdian]

OK

That's fair enough.

When all hell breakes loose we can each write our reports - and the aviation fraternity can learn from decisions made which will be good, or bad, or somewhere in-between.

RTO's, regardless of how close to V1, are still part of training - are they not??

Cheers

[c100driver]

Yes V1 aborts are part of the training but they still get cocked up with regularity outside of the simulator. A T/R light is just a light not an actual reverser deployment.

[Stan Woolley]

But it's a Boeing light!

How could it possibly be telling us something that isn't true?

[Harry Cane]

Thanks a lot guys for your different opinions about Reverser Unlocked light during takeoff roll. Just one thing I want to point out, and makes me rethink the subject over and over. That was the accident of a Fokker 100 in Sao Paulo (CGH) in 1986. The cause of the mishap was a Reverser Deployment after rotation with a fatal outcame.

Thanks again for the help,
H. C

[lomapaseo]

Thanks a lot guys for your different opinions about Reverser Unlocked light during takeoff roll. Just one thing I want to point out, and makes me rethink the subject over and over. That was the accident of a Fokker 100 in Sao Paulo (CGH) in 1986. The cause of the mishap was a Reverser Deployment after rotation with a fatal outcame.

Thanks again for the help,
H. C

I don't think that you have the details correct, but lets not let a single one-off event cloud the discussion.

The go-no-go decision needs to be appropriate for the aircraft type and experience both pro and Con. I just happen to be strongly on the side of following the manufacturers recommendations since they have access to all the data and recommended training material.

Also as I understand the original question it has to do with a warning light, and not necessarily with a mechanical outcome. However if you would like to expand the question then please be specific.

[SNS3Guppy]

Just one thing I want to point out, and makes me rethink the subject over and over. That was the accident of a Fokker 100 in Sao Paulo (CGH) in 1986. The cause of the mishap was a Reverser Deployment after rotation with a fatal outcame.

That particular incident really deserves it's own discussion. It wasn't a case of a reverser light illuminating prior to rotation. In the case of the fatal TAM flight, the autothrottle was engaged. The autothrottle attempted to retard power, and the first officer pushed it up twice, complicating the problem and making it worse. He was fighting the autothrottle which was attempting to adjust the thrust levers, and finally disengaged it and pushed up the power manually on both powerplants...sealing their fate.

The fact that the thrust reverser deployed wasn't what brought them down. it was their insistance on not recognizing that the reverser had deployed and repeatedly fighting the airplane while using the incorrect response. One has to recogize the problem that exists in the first place, in order to do something about it, and the crew wasn't aware that a reverser was deployed, at all. You really can't compare that situation to the discussion at hand.

With a reverser deployment, retarding the power on the affected engine is critical. There's really not much one can do that's worse than pushing the power up on the affected engine...repeatedly. It's a different topic than a rejected takeoff, however...and with a reverser unlock light on takeoff, we're not talking about an unsafe condition that places the ability of the airplane to fly in question. We're talking about a light, with no other indications. One can't handle an emergency that doesn't exist, and by rejecting the takeoff for that light, one is creating an emergency when one didn't exist.

Be careful of scars earned from battles in which you should never have fought.