Speedbrakes upon RTO

[JoeDiamond 67]

You may prefer continuing the takeoff to making a high speed RTO, if it's only an pack failure. 

 

Once you enter the high speed abort region, above 80 knots in our case, you aren't going to be aborting for a pack failure.  In the high speed region the list of items to abort for gets much shorter.  Engine fire, engine failure, predictive wind shear warning, or anything that makes you question the airplanes ability to fly would be the main reasons for a high speed abort.

[BlueStar 323]

The aircraft is decelerating as soon as you pull the thrust levers back. How long does that take? The speed may well peak above V1 but that doesn't matter. V1 is the decision speed, not a maximum which if exceeded you must take off.

Kevin,

 

Once the airspeed reaches V1 then a successful RTO is no longer assured. V1 is not the decision speed, it is the point where the RTO must have been initiated. The RTO initiation is brakes, engine to flight idle and spoilers applied. The time from which the braking starts until the engines are brought to flight idle is about a second or second and a half. I feel that the V1 call ("GO") must be completed before reaching V1. A warning call such as "Continue" (or an airspeed call) prior to reaching the V1 call is also important.

 

Just as a point of clarification when I talk about high speed aborts I am talking about aborts at or near V1.

 

blaustern

[kevinh 409]

Kevin,

 

Once the airspeed reaches V1 then a successful RTO is no longer assured. V1 is not the decision speed, it is the point where the RTO must have been initiated. The RTO initiation is brakes, engine to flight idle and spoilers applied. The time from which the braking starts until the engines are brought to flight idle is about a second or second and a half. I feel that the V1 call ("GO") must be completed before reaching V1. A warning call such as "Continue" (or an airspeed call) prior to reaching the V1 call is also important.

 

Just as a point of clarification when I talk about high speed aborts I am talking about aborts at or near V1.

 

blaustern

V1 is the decision speed. A significant failure before the V1 call means a takeoff is aborted, after the V1 call it is continued. It's very clear and it has to be so. Having a warning call would only cause confusion. V1 is calculated including an allowance for reaction times, etc.

 

You initiate the RTO as soon as a failure is identified and as long as V1 has not been called.The RTO does not commence when reverser and speedbrake are fully deployed. As soon as you close the thrust levers you are committed to stop.

By suggesting there should be a new "GO" speed below V1 you are changing the basis on which all aircraft takeoffs are certified.

[ESzczesniak 128]

Once you enter the high speed abort region, above 80 knots in our case, you aren't going to be aborting for a pack failure.  In the high speed region the list of items to abort for gets much shorter.  Engine fire, engine failure, predictive wind shear warning, or anything that makes you question the airplanes ability to fly would be the main reasons for a high speed abort.

 

Just to echo and emphasize this point.  If you listen to most take off briefings, they will say something like "below 80 kts I'll abort for any failure or abnormality, above 80 kts I'll abort for engine fire/failure..." (condensed for brevity).

[skelsey 765]

Kevin,

 

Once the airspeed reaches V1 then a successful RTO is no longer assured. V1 is not the decision speed, it is the point where the RTO must have been initiated. The RTO initiation is brakes, engine to flight idle and spoilers applied. The time from which the braking starts until the engines are brought to flight idle is about a second or second and a half. I feel that the V1 call ("GO") must be completed before reaching V1. A warning call such as "Continue" (or an airspeed call) prior to reaching the V1 call is also important.

 

Just as a point of clarification when I talk about high speed aborts I am talking about aborts at or near V1.

 

blaustern

 

To be pedantic: V1 is the maximum speed for the first action to initiate the RTO (Annex I to IR-OPS), which could be any one of the items you specified, not all of them. So yes, technically this means that the decision needs to be made fractionally before, hence some operators requiring that the V1 call be initiated just before the actual speed is reached so that the call is completed at V1. The implication being that you must have initiated the first action before the call is completed.

 

However, earlier you said:

 

 

 

if I'm even close to V1 I'm go'n.   

What would you define as "Close to V1"? V1 -1kt? V1 -5kt? V1 -10kt? If you have an engine failure below V1 and continue because you "don't do high-speed aborts", can you be certain that you will clear the obstacles/terrain at the end of the runway?

[19dcavscout 39]

I think the confusion here is what V1 is. V1 is that decision speed. All of your takeoff and aborted takeoff performance charts are built with that in mind. It shouldn't be before, it is right then. Unless you hear V1, you abort the takeoff. If you hear it, you continue. Trying to stay conservative on the matter could have detrimental results.  

If you decide that your GO/NO-GO speed is V1-5.  You have an Engine Failure at that speed and because of trying to be conservative, you attempt the takeoff anyways instead of conducting an RTO. You will eventually climb through V1, Vr, and begine to climb, but you have added a tremendous amount of distance in order to attempt to clear a 50 ft obstacle at the end of the runway.  Look up ACCEL-GO charts compared to ACCEL-STOP.  ACCEL-GO distances can sometimes be nearly double the runway required.  

And honestly, worse case, you decide to go before V1 and crash the airplane, that will be something the investigation will focus on. "Why did the pilot in command choose to continue the takeoff before V1 when there was time and runway distance remaining to reject it.

[Driver170 42]

Remember that V1 is not the maximum speed at which the captain can decide to initiate the rejected takeoff, but the maximum speed during takeoff at which the captain or PF must take the first action (close thrust levers) to stop the airplane ! The decision to stop must have been made prior to V1

[scandinavian13 5,192]

Seems like one of those discussions where hairs are split for no true good reason. A lot of this would be covered under 91.3, and like always, you simply have to own up to your decision. This isn't as clear cut and dry as people seem to be making it.

 

Plus, if you lost an engine at V1-5, but somehow didn't have enough room/power to accelerate, that would indicate that you really don't have the power reserve to climb away, which is a certification requirement of the aircraft.

[pcubine 143]

Remember that V1 is not the maximum speed at which the captain can decide to initiate the rejected takeoff, but the maximum speed during takeoff at which the captain or PF must take the first action (close thrust levers) to stop the airplane ! The decision to stop must have been made prior to V1

Once you have gone beyond V1 all you can do is rotate. Whatever problem you had at V1 is going into the air with you.

[Driver170 42]

Realise and react.

 

Its simple...let's consider this -

 

If you have a warning at 100kts, you reject without question!!

 

If you have a very long runway, you reject. But don't go smashing on MAX manual braking etc consider BCS.

 

around 10kts to V1, runway not as long, you can continue, sort out the thing at 400ft (fly the aircraft) and return to land with the whole length of the runway available to you.

 

you can add more scenarios to that.

 

lesson is, safer to continue the takeoff and come back for a landing rather than betting on being able to stop with/in the ASDA with high energy and without any other incident (ex: blown tires)

[ALF1 15]

Not sure why all the discussion about V1. It is clearly defined as decision speed. Other airlines say "GO". The Pilot flying takes his hand off the thrust levers and grabs the yoke with both hands discarding messing around with the power thereafter and committing to rotate the airplane.

 

Simple.

[skelsey 765]

around 10kts to V1, runway not as long, you can continue, sort out the thing at 400ft (fly the aircraft) and return to land with the whole length of the runway available to you.

Tyre failure -- sure. Engine failure -- not necessarily. Your "go" performance OEI is only guaranteed from V1. The reduced acceleration with an engine out will alter your net flight path and if you are terrain/obstacle limited you may find yourself much closer to that terrain than you bargained for.

 

The OEI screen height is 35 feet. Wet, it's just fifteen feet. Do you really want to "go" on one engine from V1 -10kt? Sure, there are margins built in etc etc -- but the whole point of the margin is that we avoid using it intentionally, the same way as we avoid intentionally dipping in to our final fuel reserve or intentionally exceeding Vmo by a couple of knots etc etc.

 

That said, the risks involved in an high-speed RTO are not to be underestimated and the high speed/low speed reject items should be well covered in the takeoff brief. Obviously if something outside the briefed items occurs then it is up to the Captain to make a judgement on the safest course of action, which in many cases may well be to continue and deal with the problem in the air.

Not sure why all the discussion about V1. It is clearly defined as decision speed. Other airlines say "GO". The Pilot flying takes his hand off the thrust levers and grabs the yoke with both hands discarding messing around with the power thereafter and committing to rotate the airplane.

 

Simple.

To be clear -- neither EASA nor the FAA define V1 as "decision speed".

 

EASA:

‘V1’ means the maximum speed in the take-off at which the pilot must take the first action to stop the aeroplane within the accelerate-stop distance. V1 also means the minimum speed in the take-off, following a failure of the critical engine at VEF, at which the pilot can continue the take-off and achieve the required height above the take-off surface within the take-off distance.

 

FAA:

V1 means the maximum speed in the takeoff at which the pilot must take the first action (e.g., apply brakes, reduce thrust, deploy speed brakes) to stop the airplane within the accelerate-stop distance. V1 also means the minimum speed in the takeoff, following a failure of the critical engine at VEF, at which the pilot can continue the takeoff and achieve the required height above the takeoff surface within the takeoff distance.

 

Technically, therefore, in order to take the "first action" no later than V1 the actual decision to reject needs to have been made fractionally before. Some airlines account for this in their SOPs by requiring the "V1" callout to be made at, say, V1 -5kt so that you finish saying "Vee One" just as the aircraft actually reaches the V1 speed. Thus the decision/first action must be taken before the V1 callout is completed. After that you are going.

 

Having said that, if you pull the TLs back at V1 +1kt are you definitely going to go off the end of the runway? Of course not, any more than the aeroplane is going to fall out of the sky if you fly a knot below minimum manoeuvring speed. But as I say, the margins are there as an extra buffer, not to be used as a matter of routine.

[Stearmandriver 2,266]

Wow, in all the airline qual cycles I've been through and all the new hires I've worked with on OE, I've never seen anyone get down in the weeds like this about what is intentionally designed to be a simple concept! ;-)

 

V1 is the decision speed, period. There's a low speed call out somewhere in the takeoff roll, typically 80 knots or 100 knots, that serves as an airspeed cross check and to signal the transition into the high speed regime, and then there's V1 which signals you're going flying. Company SOPs will usually instruct an abort for any abnormality below the low-speed call, and contain a (short) list of mandatory items to abort for in the high speed regime (to which is usually appended a judgement clause along the lines of "or any time the captain feels the airworthiness of the aircraft is in doubt"). Some companies call V1 at 5 knots prior to allow for human reaction time to initiate the abort, that's all.

 

All this debate about "well I use V1 -10", "well I'm still aborting a few knots above V1 as long as I have the length, on a dry runway, with acceptable density altitude, on a Tuesday when I'm wearing my xmas tie" type stuff is actually missing the point of why the V1 concept is structured the way it is.

 

The captain, way back when, used to make the abort decision just using his judgment. This didn't work so well, because pilots, like all human beings, get complacent. After thousands of uneventful takeoffs, you can't expect the guy to be a hero and nail it the one time something goes bad - which will probably happen on an early morning after a late night in lousy weather with a performance-limiting MEL etc. So, we compute a decision speed for every takeoff that takes all performance factors into account, and that's it. It's designed to remove the need to think at all in a high-speed, high-workload, high-stress, high-surprise and high-stakes moment of time. No person, at that moment, will ever be able to instantaneously make a determination anywhere near as precise as the team of engineers who took their time to develop the takeoff data, including a decision speed, for every possible takeoff.

 

Then there's the fact that humans always fall back on their training in times of surprise and stress. If you've always trained to abort below V1 and fly above it (and you have because all training programs are structured that way), that's what you'll do on the line, no matter your intentions and no matter what you've briefed. So you may as well keep your intentions and briefings in line with your actions ;-).

 

This one doesn't need over-complication, guys. There's times we want you to think... and times we don't. Bad problem below V1, abort. Bad problem above V1, fly. The end.

[ALF1 15]

I am glad you stepped in Andrew. This is what I have been saying in another post.

 

Knowing who the pros really are, on this operational concept by the pros day in and day out through the ages I will take their opinion over any other.

[Bobsk8 12,669]

I have known a few pilots and CFI's as well who liked to adjust the rules to fit their idea of how it should be. Two of them are no longer with us, and I suspect that one of their self designed rule adjustments was partially to blame. I won't fly with any pilot that has that attitude.