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Balanced Field Length, V-speeds

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GravityHater

Well-known member
Joined
Aug 12, 2004
Posts
1,168
I am trying to figure out why we do not adjust anything with respect to V speeds, when the runway is huge as in multiple so of the BFL.
Lets say the BFL is 3500' and the actual length is 12000' (I have experienced something similar).
Just past V1, still on the ground, you lose one - or have a fire. You are probably 2500' down the runway (CJ). All the training says Go..... but it seems like we ignore the fact that you can easily stop in these circumstances.
Tell me what I overlooked.
 
Overlooked? Nothing. You're right.

V1 decision speed only comes into play on an abort critical or obstical critical runway. If you've got room ... you've got room!. I like room ...

Just be certain you know what you're doing. Most folks don't.

In many of the advanced FMS/Perf systems you can adjust V1 to account for an abort critical or obstical critical situation. Older "Tab Data" on a checklist won't do it.

TransMach
 
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It may also depend on what type of aircrat you fly. On the F900, V1/Vr are the same speed, so at the V1 call, you are removing your hand from the throttle, starting rotation and are effectively flying. When there is a significant delay between the two speeds, I have heard of pilots matching V1/Vr on a long runway.
 
You've overlooked nothing....but you are applying common sense and critical thinking to a situation.

Doing that removes you from the "train like you fly, fly like you train" mindset and could possibly cause you issues if you hesitate on a runway that is shorter.

If I bang an engine at V1 1/4 down a long runway, I know I'll have PLENTY of runway to return to for a OEI approach and landing...and I'll take those odds over the proven higher risk from a high-speed RTO any day.
 
You've overlooked nothing....but you are applying common sense and critical thinking to a situation.

Doing that removes you from the "train like you fly, fly like you train" mindset and could possibly cause you issues if you hesitate on a runway that is shorter.

If I bang an engine at V1 1/4 down a long runway, I know I'll have PLENTY of runway to return to for a OEI approach and landing...and I'll take those odds over the proven higher risk from a high-speed RTO any day.


agreed! a high speed abort is no good on any runway.
 
V1 can also be brake energy limited. Abort past V1 and you're no longer in the realm of the calculated and tested and certified performance. Prang it up and the FAA will crucify you. High speed, high weight abort, you don't really know what will happen. Blow the tires, depart the paved surface etc.
 
I am trying to figure out why we do not adjust anything with respect to V speeds, when the runway is huge as in multiple so of the BFL.
Lets say the BFL is 3500' and the actual length is 12000' (I have experienced something similar).
Just past V1, still on the ground, you lose one - or have a fire. You are probably 2500' down the runway (CJ). All the training says Go..... but it seems like we ignore the fact that you can easily stop in these circumstances.
Tell me what I overlooked.
You become the test pilot if you abort after V1. If you continue the takeoff single engine after V1 the plane has proven to perform if you continue. High speed aborts can lead to some very ugly things.
 
It may also depend on what type of aircrat you fly. On the F900, V1/Vr are the same speed, so at the V1 call, you are removing your hand from the throttle, starting rotation and are effectively flying. When there is a significant delay between the two speeds, I have heard of pilots matching V1/Vr on a long runway.

Don't you mean V2 and Vr are the same speed in the DA-50 or DA-900? we always rotate at V2, not V1.
 
You are referring to balanced field length. I am not sure what type airplane you fly, but V1 is adjustable in my airplane (G4).

If you are field limited you can use V1min (shortest accelerate stop-longest accelerate go).

Or when using a contaminated runway for example you may use V1max (longest accelerate stop-shortest accelerate go).

Check the AFM and see if it allows for changing V1. Using balanced field is fine most of the time, but it is not always the safest option. If you are not runway limited and don't feel good about high speed aborts you can use V1 min every time if you want. But I agree that you would be crazy to disregard the training you have received and choose to do something in the test pilot realm during an emergency. That is not the time to be jumping "outside the box", so to speak.
 

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