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Procedural question for an Evergreen pilot

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ootskdog

Well-known member
Joined
Dec 27, 2005
Posts
66
I am working on a study regarding rejected takeoffs.

At Evergreen International Airlines, do you still use V1 minus 8kts for your actual V1 speed?

In other words do you still bug V1 at a speed that is actually 8 knots less than V1, to give yourselves additional time to reject?

Thanks in advance Zoners!
 
One of the best studies done on V1 speeds was done by Luftansa. Many airlines (including mine) call "V1" at V1-5kts. The bug is still set at V1. Basically it allows you to have the aircraft decellerating AT V!.
A 2 second delay at V! can have you departing the end of the runway at 50-70kts. (depending on type of aircraft) I can send you a good training vid if you are interested.
 
But an engine failure at V1 minus 4 secs can have you taking out trees at the edge of the airport, or worst yet, just clipping that low hill out there.

Whats wrong with V1 being V1.
 
I am working on a study regarding rejected takeoffs.

At Evergreen International Airlines, do you still use V1 minus 8kts for your actual V1 speed?

In other words do you still bug V1 at a speed that is actually 8 knots less than V1, to give yourselves additional time to reject?

Thanks in advance Zoners!

Yup...still doin it that way.
 
But an engine failure at V1 minus 4 secs can have you taking out trees at the edge of the airport, or worst yet, just clipping that low hill out there.

Whats wrong with V1 being V1.


well the numbers are supposed to be somewhat conservative. remember this data is based on power being set by 80 kts, but in many cases your pwr is set well prior to that. What about eating too much rwy in your lineup distance prior to advancing the throttles? That sometimes is or isnt accounted for. Theres a lot of buffers in there.

then theres crossing the threshold at 0 ft versus 35ft etc.
 
what about taking off at v1 minus 8 will the plane get airborne and clear the obsticales in the second segment climb. rember v1 is the decision speed at which you can safely take the aircraft into flight or stop in the remaining distances. i think that there are much smarter people than me that figure this stuff out and a room full of others backing them up. why not just use the published numbers.
 
Thanks avpro91.

Many Boeing operators use V1 - 5kts, I was pretty sure that Evergreen was -8 kts, but I wanted to check. It's been a long time since I last flew 486EV ;)

Thunderworm, remember that V1 is not a decision speed.

It is the speed which represents:
  1. [FONT=Arial, Helvetica, sans-serif]The maximum speed by which a rejected takeoff must be initiated to assure that a safe stop can be completed within the remaining runway, or runway and stopway; [/FONT]
  2. [FONT=Arial, Helvetica, sans-serif]The minimum speed which assures that a takeoff can be safely completed within the remaining runway, or runway and clearway, after failure of the most critical engine at a designated speed; and [/FONT]
  3. [FONT=Arial, Helvetica, sans-serif]The single speed which permits a successful stop or continued takeoff when operating at the minimum allowable field length for a particular weight.[/FONT]
In other words, if you are going to reject the takeoff, you need to be accomplishing the rejected takeoff maneuver (ie Thrust Idle, S/Bs, Reversers) before reaching V1.
 
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Thanks avpro91.

Many Boeing operators use V1 - 5kts, I was pretty sure that Evergreen was -8 kts, but I wanted to check. It's been a long time since I last flew 486EV ;)

Thunderworm, remember that V1 is not a decision speed.

It is the speed which represents:
  1. [FONT=Arial, Helvetica, sans-serif]The maximum speed by which a rejected takeoff must be initiated to assure that a safe stop can be completed within the remaining runway, or runway and stopway; [/FONT]
  2. [FONT=Arial, Helvetica, sans-serif]The minimum speed which assures that a takeoff can be safely completed within the remaining runway, or runway and clearway, after failure of the most critical engine at a designated speed; and [/FONT]
  3. [FONT=Arial, Helvetica, sans-serif]The single speed which permits a successful stop or continued takeoff when operating at the minimum allowable field length for a particular weight.[/FONT]
In other words, if you are going to reject the takeoff, you need to be accomplishing the rejected takeoff maneuver (ie Thrust Idle, S/Bs, Reversers) before reaching V1.


That is correct, EV still uses V1-8kts and actually bugs this speed. Furthermore, many people incorrectly say that V1 is the decision speed, IT IS NOT. Like any other regulation or definition in any gov. manual, you must read carefully and completely.

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 takoff, 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.

V1 is the maximum speed by which an abort can be INITIATED. doesnt matter if your V1 is 100kts in a small plane or 160kts in a B747, if you bug that speed and actually have a V1 cut, you will be initiating the abort actions AFTER that speed. This is why it is good procedure to actually bug a lower speed. Now the acceleration rates vary if it is 100 or 160kts, however most jets use a balanced field length. The bigger heavies also include clearways and special engine out procedures for each specific airplane and runway. Quickly looking at the situation like someone posed, you could be making the decision to continue before the minimum speed that assures a safe takeoff. However the safe "buffer factor" used to reference a lower V1 speed also applies to the later part of the definition. If the speed were kept at V1 and an engine fails at that speed, the average pilot will actually make the decision to keep going after V1 (same as if he were making the abort decision). But now since the V1 speed is bugged lower, then by the time the pilot makes the decision to continue (assuming there are no controllability issues), based on the acceleration rates, that decision will still be made by the MINUMIM V1 SPEED, thus still satisfying the requirements of the definition. Just like there are gross climb requirements for climb gradient in climbout for test pilot/airplanes given ideal conditions, the FAA allows for a reduction to NET CLIMB GRADIENT, which is the gross climb gradient reduced by .8% (2-eng a/c), which is required by FAR 25 for terrain clearance determination to allow for variables in performance. (actual airplanes in line use, with different atmospheric conditions with pilots WHO ARE NOT ANTICIPATING ENGINE FAILURES)

In any case, these remain techniques. The FAA obviously doesn't regulate that it should or should not be used. I just cant see how if using the actual speeds, you will INITIATE any abort by V1 speed in any airplane. I also at first, thought about the back end of it, which some people have brought up, that says that you will be basing the go decision on a speed lower than the minimum speed for continued safe takeoff (back end definition of V1), however as i said above, actual response time to actually make the decision to go, will still be made BY V1, not before or after it.

just my opinion.....
 
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you guys are all right but the v1 speed is based on reaching that speed and having 1 sec to complete the actions and 2 sec of buffering time so that is three seconds after reaching the v1 speed and still make the reqired distance. however if you have an engine failure 2 seconds before v1 and continue the takeoff you will only clear the end of the runway by 15feet. so there is a lot of room for interpitation that is why i say let v1 be v1 since the guys who came up with the number are way smarter than me and give us plenty of buffering time since they know that i react as fast as i type. which it took me about five minutes to write this.
 

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