4th June 2010 B737-800 rejected takeoff after V1 Report is out

[aviatorhi]

What the above post said, and under dry conditions reverse thrust isn't taken into account. Not suggesting you should abort after V1 with confidence, but it's useful to know what the numbers are telling you.

On another note, the jet operations I've seen typically allow either pilot to call for an abort but the CA will take over the controls to perform the abort.

[pattern_is_full]

I thought the concept of V1 was primarily linked to "balanced field length."

Balanced field takeoff - Wikipedia, the free encyclopedia

- so, as some have said, if there was room to stop, then by definition the speed called out as "V1" - really wasn't.

With a runway long enough (say, 33,000 ft/10,000 m), one might reach Vr and V2 long before reaching "V1" for that particular runway and any particular aircraft weight.

But that raises the question - how was "V1" for this particular takeoff calculated? Since it doesn't appear to have fit the definition of V1.

[PLovett]

pattern_is_full, I am sure someone far more knowledgeable than myself can express it more eloquently but V1 is more than just balanced field length where there is excess runway length. It also marks a transition from takeoff to flight; a point where it is no longer a rejected takeoff but a form of touchdown and landing that would follow in the event of closing the throttles.

[BOAC]

As PL says.

Pif - read the first para of your reference again. The balanced field merely says the two distances are equal. With shorter runways this limits V1.

Long runway, smaller (737 type ) a/c

Vr is achieved well before the end of the runway. This defines the take-off distance required (allowing for an engine failure at 'V1' which will always be above Vmcg). Start with Vmcg as your V1. Long runway - a/c can accelerate from Vmcg on 1 engine and safely get airborne at Vr with room to spare. Can it stop from Vmcg in the distance available? Yes.

Now push V1 up towards Vr (V1 is limited by VR since we do not normally try to stop when airborne). Check the a/c can both accelerate from 'V1' to Vr AND stop from Vr in the remaining runway - yes. Thus V1 is equal to Vr.

V1 (normally) always represents the speed at or above which the take-off will be continued. It is important therefore to continue annunciating it in a crew since mind-sets change at that point and hands are removed from throttles (to prevent an inadvertent/incorrect stop). The call will be "V1/Rotate".

IN your case you are right, V1 is NOT the limiting stop factor. It is, however, normally the limiting 'go' factor' since at that speed you 'do aviation'. No-one says you will not be able to stop at Vr (or above) on a long runway. There have been instances where it has worked, many where it has failed. It is just that there are very few situations where it is desirable, eg double engine failure, jammed controls, a particularly dangerous a/c condition where the a/c would not successfully fly to a controlled landing to name a few.

[aterpster]

pattern is full:

With a runway long enough (say, 33,000 ft/10,000 m), one might reach Vr and V2 long before reaching "V1" for that particular runway and any particular aircraft weight.

With a light aircraft and a reasonably long runway this often happens. Where I worked V1 and Vr were the same in those cases. Otherwise, for us at least, VR set V1 in those circumstances.

[Teddy Robinson]

Surprised nobody has posted this

http://

http://http://www.youtube.com/watch?v=7VumXN8RNO8&feature=related

Scheduled performance is covered up to V1 stop/go, after V1 airborne, there is no data for stopping after V1, ergo, one is no longer protected if one decides to abort post V1.

[lomapaseo]

Scheduled performance is covered up to V1 stop/go, after V1 airborne, there is no data for stopping after V1, ergo, one is no longer protected if one decides to abort post V1.

seriously you are only protected if the pilot has sufficient skills and reactions to stop. The data shows that this is true in only 95% of the abort stops above 100kts.

[Tee Emm]

All this means that the crew probably knew that there was a safe margin

Try again. The copilot acted impulsively and there was no way he would have been certain the aircraft could have pulled up safely. The captain didn't have a clue what the copilot was going to do until it was too late for him to prevent the copilot's idiotic action.

It would be instructive for the investigation to have closely examined the copilot's history during his time with the operator. A highly dangerous impulsive action as was demonstrated sometimes means he has had problems during his type rating and line training. Not always of course but this behaviour is usually not isolated.

The Dutch incident report is notable by its addition of a large amount superfluous technical references to various manuals and other similar authoritive data. Very little of substance came out of the report.

[IGh]

Capt's DUTY to over-come T/O DISTRACTION

Tee M mentioned (just above):

"... captain didn't have a clue what the copilot was going to do until it was too late for him to prevent the copilot's idiotic action...."

I've got a file full of such HF failure-interactions -- the hazard is much the same while accelerating on the RWY, and during the initial CLIMB-out. F/O can be your major distraction, and the CAPT must firmly correct these mis-steps, very quickly. Maybe the CAPT should KEEP his RIGHT HAND backing the Throttles after V1. [In other cases it was the Captain who incorrectly responded to a Takeoff DISTRACTION, and the F/O had to intervene.]

In other T/O upset mishaps, the F/O became the distraction, drawing attention to some irrelevant issue during a critical interval just after T/O. There were numerous Stall Warning events (hull loss) just after Takeoff -- where the Capt should have intervened to prevent F/O's abrupt response to that nuisance-warning.

During the F/O's Takeoff, it is difficult to COMMUNICATE the nature of a subtle concern (scrubbing NLG tire, rudder-pedal failure, rudder-pedal forces, erroneous airspeed indication, Seat rollback) -- there are too many cases to easily summarize the variety of Takeoff DISTRACTION that deserved quick action by the Captain.

[Rananim]

No matter how shallow the cockpit gradient,I am a firm believer that the RTO is always the Captain's decision,never the co-pilots.

[MountainBear]

There have been instances where it has worked, many where it has failed. It is just that there are very few situations where it is desirable, eg double engine failure, jammed controls, a particularly dangerous a/c condition where the a/c would not successfully fly to a controlled landing to name a few.

The difficulty BOAC is that the conditions upon which an aircraft will not fly after V1 are subject to interpretation. Sometimes the precursors to dangerous conditions are subtle. For me, the whole discussion boils down to an issue of professional judgment. And where there is professional judgment there is by definition discretion. And where there is discretion there is by definition a gray area, a range of behaviors where reasonable professionals can disagree.

Just because you would not do the same thing in the same situation as this F/O is irrelevant. That's not the standard I would use to judge the PF behavior. For me, the standard is whether of nor there is a rational basis for the F/O doing what he did. And the report by the Dutch authorities clearly demonstrates that there was, in fact, a rational basis for his behavior: there were in fact data anomalies (three times) recorded on the FDR. His behavior was not capricious, it was not whimsical; it was based upon fact. Interpretation of facts is the embodiment of what professional judgment means.

That's why I can't agree with Tee Emm's post that the F/O behavior was 'idiotic' or the claim that stopping after V1 is 'suicidal'. Such comments go too far. Disagreement among professionals is fair enough; outright condemnation is wrong.

[lomapaseo]

Rananim

No matter how shallow the cockpit gradient,I am a firm believer that the RTO is always the Captain's decision,never the co-pilots.

We have been through this over and over on this board month after month with similar arguments for and against with all kinds of "what if"

The middle of the road suits me fine and that is the crew brief before the takeoff what roll they will take in the decision.

[Sunnyjohn]

The captain didn't have a clue what the copilot was going to do until it was too late for him to prevent the copilot's idiotic action.

The Dutch report stated that the CVR was not operating. Therefore there does not appear to be a record of conversation during the aborted takeoff. Unless I missed it somewhere, I don't see how we can be sure about this without a record of the flight deck conversation.

[euroflyer]

I wonder what the f/o would of done on a short runway out of CIA...
Had he done the same then it would be a different outcome so how can some people on this forum actually think his actions were correct?!
I think he had no idea if they could stop safely after v1, it was just pure luck they stopped in time, the guy obviously had concerns about the aircraft but at that speed after v1 his actions were totally unsafe.

[Herod]

Does anyone have a link to a report on the accident in post 68? It seems the nose was raised for some considerable time; wonder why it didn't fly?

[Land and Hold Short]

RTO by the F/O

Maybe they should change their SOP'S to if the Capt is the PM, the F/O sets 40% N1, Capt Calls engines stable, F/O presses TOGA advances the Thrust Levers and Capt then Has the Thrust Levers.

Therefore any decision to STOP or GO is solely the Capt's decision. No way for the F/O as PF or PM to abort a T/O. But he can Call STOP or ABORT!!

Just my 2 cents.

[The Ancient Geek]

For $diety's sake, why do we need so much nitpicking.

The PF realised that something was wrong. He had plenty of room to stop.
He aborted and stopped safely. Well done that man.
Having been in a similar situation, albeit in a Twotter with more than plenty of room, I can assure you that it is not a nice experience. There will be a crease in the seat and a change of underwear may have been required.

Fast reactions combined with familiarity with both the aircraft and the field all contributed to a safe outcome. Would the aircraft have been safe to fly if he had continued ?, on balance it probably would, but he had no way of knowing that in the available decision time.

In other circumstances the outcome could have been very different but IN THIS CASE experience and fast reactions saved the day.

[bubbers44]

My airline SOP is the captain makes the abort decision so he has the throttles once set by the FO. It eliminates any question about who aborts. I have taken off on 13,000 ft runways when we only needed 5,000 ft so knew the V1 speed was a legality, not a safety speed. I knew after V1 I could stop with just reverse as in a normal landing and have no brake problems. I also knew I would have a lot of explaining to do even though I cleared with minimum braking with 5,000 ft left. Sometimes it is easiest to follow the rules even if they don't make sense.

[HidekiTojo]

SOP's are right and correct 99% of the time. The other 1% anything goes and if the outcome is successful then so be it. I don't see the huge deal here. As pilots we usually know when we have room to stop or not. Dash 8 at Paris can go through V1 twice and stop.

The FO was faced with a very strange situation here, had he continued and impacted in a cabbage patch 1km away what would people here be saying then?

[pattern_is_full]

Thanks for the replies - obviously there has to be a go/no-go point, and V1 is the logical (and usually inarguable) choice.

Bust it and succeed, and you'll have some splainin' to do.

Bust it and fail as per video, and you'll have even more splainin' to do (if still around to do so.)