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balanced field
- Thread starter rk772
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Basic explanation:
Balanced field length occurs when the calculated accelerate-stop distance is equal to, or less than, the available runway length.
FAR 121 allows for the consideration of stopway lenght, but some airlines only use runway lenght to stay conservative.
It can be explain in much more detail but just keep it simple.
We are pilots right? Just fly the plane. If it says you can go.
Balanced field length occurs when the calculated accelerate-stop distance is equal to, or less than, the available runway length.
FAR 121 allows for the consideration of stopway lenght, but some airlines only use runway lenght to stay conservative.
It can be explain in much more detail but just keep it simple.
We are pilots right? Just fly the plane. If it says you can go.
JetPilot500
Well-known member
- Joined
- Dec 5, 2001
- Posts
- 335
Lets clear this up a little.
Balanced Field Length (BFL) is NOT when Accellerate-Stop equals the runway length!
BFL is when:
Accellerate Stop = Accellerate Go
When you have a "Balanced Field" you require the least amount of runway for takeoff.
Definition of V1: The speed at which you make your decision to Abort or Continue a takeoff. If a problem arises before this speed you abort. If a problem occurs at or after this speed you continue the takeoff (unless the plane is unflyable).
The BFL is determined by adjusting your V1 Speed so that the Accel Stop and Accel Go distances are the same.
If you selected a higher speed for V1 your Accel Stop would be Greater than your Accel Go. In other words, since you could abort at a higher speed it would take a longer distance to stop the airplane than it would if you made your decision to abort at a lower speed since you have more decellerating to do. Accel Go would be less because your V1 Speed is closer to VR and you have less accellerating to do with an engine inoperative.
On the other hand, if you lower your V1, then your Accel Go is greater than your Accel Stop. In this case, it would take longer to continue your takeoff with an engine inoperative from a lower speed since it would be harder to accellerate to VR with an engine inop. However your Accel Stop would be less since you decide to make your abort at a lower speed and you have less speed to lose.
Either way, the distance required is greater than if you have a Balanced Field.
Hope this helps,
JetPilot500
Balanced Field Length (BFL) is NOT when Accellerate-Stop equals the runway length!
BFL is when:
Accellerate Stop = Accellerate Go
When you have a "Balanced Field" you require the least amount of runway for takeoff.
Definition of V1: The speed at which you make your decision to Abort or Continue a takeoff. If a problem arises before this speed you abort. If a problem occurs at or after this speed you continue the takeoff (unless the plane is unflyable).
The BFL is determined by adjusting your V1 Speed so that the Accel Stop and Accel Go distances are the same.
If you selected a higher speed for V1 your Accel Stop would be Greater than your Accel Go. In other words, since you could abort at a higher speed it would take a longer distance to stop the airplane than it would if you made your decision to abort at a lower speed since you have more decellerating to do. Accel Go would be less because your V1 Speed is closer to VR and you have less accellerating to do with an engine inoperative.
On the other hand, if you lower your V1, then your Accel Go is greater than your Accel Stop. In this case, it would take longer to continue your takeoff with an engine inoperative from a lower speed since it would be harder to accellerate to VR with an engine inop. However your Accel Stop would be less since you decide to make your abort at a lower speed and you have less speed to lose.
Either way, the distance required is greater than if you have a Balanced Field.
Hope this helps,
JetPilot500
Last edited:
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