engine falilure after V1 before VR and a long runway?

[CA1900]

Yeah, but the guy asking the question seems to be flying ATR42s.

Them things may be a different animal than a high-performance jet.

Never flown an ATR or heavy turboprop, but guessing on a V1 speed of 88 knots, Vr 92..?

On a 12000 feet runway?

Perhaps a safe abort after V1 could be made.

Then what's the point of calculating it at all? "Perhaps" doesn't cut it. All your runway and performance data is predicated on following the speeds and procedures properly, and that includes continuing if there's a problem after V1. Trying to abort past V1 is inviting disaster.

That was my reason for posting the link to the Mesa accident in Bangor, in fact. They took off from an 11,500-foot runway, with a fairly small and agile turboprop (~17000 pounds). They tried to "abort" after V1 (in fact, right as they got into the air), and they had so much momentum at that speed, they couldn't stop it in time, even with the engines in reverse. They touched back down nearly 8,000 feet down the runway, and ended up ripping open the fuselage after they lost control in the snow.

I don't have the numbers for the ATR, but a full 1900 will have a V1 speed of 107 knots, and rotation at 109. At that speed, an abort is extremely risky.

 

[FreightGod]

Well hell, what is the point.

Lets make it even more extrme then:
Say ya are flying empty in a Cessna Twinahawk, or whatever the lighest twin is>
Ya take of from Edwards Air base with their 15K runway and their 15K overuns.

ya are light and ya loose one after V1, Vr, etc...Ya only burnded 2000 feet taking off, ya got 13,000 feet ahead to land on.

A) Should ya disregard any kind of commn sense and airmanship to try to take this sick bird around the pattern and land becuase the you have passed V1..?

B) Or should you chop the power, select full flaps and land straight ahead?
(If the gear is still down)

We do get paid fairly well to throw the book away from time to time and just fly the plane instead of the book.
Again, if this was a heavy jet, ya don't even want to think about aborting after V1......

 

[DC8 Flyer]

Disregard, I misread, we are talking engine failures.

Here is something "curious". From the DC8 chats at 220K pounds
V1 120, VR 125, V2 143. At 325K pounds (max gross) V1, VR, and V2 are 142, 152, 169. I know that the 325K numbers are good for TOL on a "cool" day. So if I am taking off at 220K my V2 is the same as the 325K's V1. The airplane will stop on the runway if the abort is at 142 knots at 325K, why wont the airplane stop on the runway at V1 + 15 at 220K pounds?? Takeoff power is temp based, not weight based (for max that is).

Not advocating aborting above V1 for an engine failure, I just think it is a new way to look at your speeds and your options should you need it.

 

[avbug]

Nothing in aviation is absolute. If there is a question if the airplane will or will not fly, ABORT!

I believe I said that...when I said every situation is unique. However, departing from a briefed takeoff is far more likely to cause problems, and high speed aborts statistically are far more likely to end up badly. Once in a blue moon something occurs that demands an abort anyway...but very, very rarely.

I've had several occasions to experience genuine priority moments during the takeoff roll, and have both aborted and continued...but attempting to abort after I've made the decision to continue would have ended badly in virtually every case.

Those extremely rare moments might occur in which one can and should still get stopped; jammed controls may certainly be among them...again, rare, rare moments, and far, far more the exception than the rule...by orders of magnitude.

 

[DC8 Flyer]

I believe I said that...when I said every situation is unique. However, departing from a briefed takeoff is far more likely to cause problems, and high speed aborts statistically are far more likely to end up badly. Once in a blue moon something occurs that demands an abort anyway...but very, very rarely.

I've had several occasions to experience genuine priority moments during the takeoff roll, and have both aborted and continued...but attempting to abort after I've made the decision to continue would have ended badly in virtually every case.

Those extremely rare moments might occur in which one can and should still get stopped; jammed controls may certainly be among them...again, rare, rare moments, and far, far more the exception than the rule...by orders of magnitude.

Absolutely right, BUT, those are, I think, what is going to end up in disaster more ofter than engine failures. The DC10 out of ORD, if the FO had not pitched to V2, the airplane would have most likely been able to limp around, but following procedure allowed the slats to retract and thus the crash. Im not advocating anarchy, but I am very much against robotism. Think outside the box, take off briefings should be short and sweet, not this below 80 knots, blah blah blah, above 80 knots blah blah blah. I think that programs everyone to go or not based on a set of standards and if something pops up that isnt within those standards, the programming takes over and the decision to continue may be made when a decision to stop would have been better.

 

[CA1900]

Once in a blue moon something occurs that demands an abort anyway...but very, very rarely...

Those extremely rare moments might occur in which one can and should still get stopped; jammed controls may certainly be among them...

Exactly. "Well, we have lots of runway left" should not be one of the factors in whether to abort after V1. "It won't fly" is about the only reason I can think of for a post-V1 abort. And those are extremely rare. As others have pointed out, high-speed aborts tend to end badly, whatever the reason.


We had just such an abort a while back -- one of our planes got to rotation speed, and the elevator wouldn't move. They aborted at a little over 100 knots on a 7000-foot runway. Fortunately it was dry and the airplane was light, so they were able to stop it in time.

As it turns out, the trim wheel was removed for a maintenance procedure, and was reinstalled 90 degrees from where it was supposed to be. Unfortunately, the trim index is on the knob, not the pedestal, so the crew had no way to know. (Raytheon's poor maintenance manual doesn't directly address this, as I understand it. Ours does -- now.)

The elevator was trimmed severely nose-down, hence the elevator feeling jammed on takeoff. We've added a procedure to the crew-change preflight to run the trims to their stops and back to center, to be sure they stop at the red lines, and that should catch it if it ever happens again.

 

[100LL... Again!]

If there is a serious concern as to whether the aircraft could actually fly, I would consider such an abort.

An extreme example might be a collision with wildlife. Anyone see the posters with the bizjet that is severely damaged by an elk, I think?

That said, COULD you abort a slower turboprop on a very long runway even after getting airborne? Sure, propbably, but why would you want to?

These are transport category aircraft, and it is important not to fly them with a GA light-twin philosophy.

 

[100LL... Again!]

We had just such an abort a while back -- one of our planes got to rotation speed, and the elevator wouldn't move. They aborted at a little over 100 knots on a 7000-foot runway. Fortunately it was dry and the airplane was light, so they were able to stop it in time.

I that situation, I think the crew made the right call. I've met some pilots that mechanically think that V1 is inviolable under any and all circumstances. Too much book-learnin' and not enough common sense.

 

[Groucho]

V1 is not a hard number anymore

With the advent of computerized weight and balance and performance data, V1 is now computed on a specific airplane, weight, temperature, and runway condition at our airline. There is no specific hard number. It can be increased for incrased cliimb performance, if runway lenght and aircraft weight are not limiting. It can be reduced with an incrased flap setting for contaminated runways to improve stopping capability.

For high hot and heavy operations, such as Las Vegas in August, V1, V2 will be upagainst the limiting tire speed, runway length considered, to improve second segment climb performance.

The fact of the matter is, is that with computerized performance data V1, V2 and other factors can be computed on a case by case basis to optimize performance.

To answer the orginal question, yes V1 can be increased to improve climb performance or some other paramater. You do not however change the way we handle V1. Once computed, by whatever method, prior to V1 for an engine failure, we stop. After V1 we continue the takeoff.

I hope we are all confused now at a much higher leve.