Calling V1 five knots early?

Tell me if I misunderstand this, but I thought that below V1 you may not accelerate to take off speed before you're out of room...correct me if I'm wrong, and goodness knows that's possible, but V1 (at that speed/day/temp) guarantees that you will reach T/O velocity and climb necessary to get out of where you're at.
 
MikeD said:
Not missing anything. You're somewhat missing what I'm saying about technique/procedure. Your technique is your procedure there because that's the only method the company adopted. And that's fine. It's sound procedure, it's safe, it works, it accomplishes what it's designed to accomplish. However other companies may use a different technique as their procedure. Both techniques accomplish the same overall objective in the big picture, but taken individually, they are indeed techniques as they are methods to accomplish a task. That's the differentiation I was using.
Click to expand...

I am not missing anything.

Techniques are more for non-safety items related to flight operations. Procedures are for safety related items related to flight operations.

So, with that said, calling out V1-5 is our procedure. Other companies call V1 at V1 as their procedure. With both of these approaches there is science and technical research that backs them up one way or another. They have adopted the procedure that they feel is best.

Finally, the V1-5 procedure reinforces the more important point that after 100 knots you are in a go orientated mode and even if you have an engine failure or fire, it is safer to deal with it in the air, bring it around and land than doing a high speed RTO.
 
Last edited:
Bumblebee said:
Tell me if I misunderstand this, but I thought that below V1 you may not accelerate to take off speed before you're out of room...correct me if I'm wrong, and goodness knows that's possible, but V1 (at that speed/day/temp) guarantees that you will reach T/O velocity and climb necessary to get out of where you're at.
Click to expand...

As stated, if you call out V1-5 by the time the other guy reacts, if there is an issue, you will be AT V1 speed.
 
PeanuckleCRJ said:
That's not necessarily the case due to wide variance in acceleration rates as well as how rapid problems occur.
Click to expand...

Not to much difference between 1.2 seconds and 2.1 seconds. Even with that, it would probably be safer to deal with the problem in the air and bring it around to land than a high speed abort within a few knots of your V1 speed.
 
Here are two incidents that really show how ridiculous this discussion is.

In this incident the crew had to rotate well beyond V1 in order to not hit the other aircraft...

http://en.wikipedia.org/wiki/2005_Logan_Airport_runway_incursion

During this incident the crew had to rotate at V1-10 knots....

http://www.ntsb.gov/aviationquery/brief.aspx?ev_id=20061115X01674

http://videosift.com/video/NTSB-animation-of-Chicago-OHare-Runway-Near-Miss

What I am getting at here is that we are paid professionals and sometimes the situation dictates we react a certain way to see a favorable outcome.
 
image.jpg

Bedtime reading anyone?
 
Seggy said:
I am not missing anything.

Techniques are more for non-safety items related to flight operations. Procedures are for safety related items related to flight operations.

So, with that said, calling out V1-5 is our procedure. Other companies call V1 at V1 as their procedure. With both of these approaches there is science and technical research that backs them up one way or another. They have adopted the procedure that they feel is best.

Finally, the V1-5 procedure reinforces the more important point that after 100 knots you are in a go orientated mode and even if you have an engine failure or fire, it is safer to deal with it in the air, bring it around and land than doing a high speed RTO.
Click to expand...

A technique is merely a method of accomplishing something. That said, particular techniques may or may not be adopted as a procedure, depending on what company wants to accept what research contained within, or have what measure of safety or accepted risk.

You have to have a technique, that gets vetted/researched properly, in order for it to become a procedure. Your company procedure is merely a different way of doing business from someone else's, not right or wrong, just different. That said, there are many techniques out there for any number of ways of doing business which have never been adopted as procedures, and may never will, since (as you allude) they are often for non-safety items.

To me, if after 100 knots you are in a "go" oriented mode (which is sound philosophy, I have no issue with that), then V1 -5 or V1 shouldn't matter in terms of "safer"........because with both you're normally well past 100 knots and should be in the "go" mode anyway. Unless your V1 happens to be 104 knots, and V1-5 brings you down to 99.

Seggy said:
What I am getting at here is that we are paid professionals and sometimes the situation dictates we react a certain way to see a favorable outcome.
Click to expand...

Agreed. Fully.
 
Seggy said:
Ahhh.....no.
Click to expand...
apparently it was during the emergency avoidance, and there is some gray area as to performance...or isn't there? I thought you just said that there are times when, on the Command Authority of the PIC that you could take off before or after V1. So the discussion about safety of a V1-5 is dumb because a captain made an emergency decision that worked out.
 
MikeD said:
A technique is merely a method of accomplishing something.
Click to expand...

So is a procedure.

That said, particular techniques may or may not be adopted as a procedure, depending on what company wants to accept what research contained within, or have what measure of safety or accepted risk. You have to have a technique, that gets vetted/researched properly, in order for it to become a procedure. Your company procedure is merely a different way of doing business from someone else's, not right or wrong, just different. That said, there are many techniques out there for any number of ways of doing business which have never been adopted as procedures, and may never will, since (as you allude) they are often for non-safety items.
Click to expand...

Nope, still not buying it.

When Boeing/Airbus puts out an aircraft they don't give the operator techniques to operate the aircraft by. They give them procedures. Airlines adopt the procedures to fit their existing operating procedures. Yes, airlines have different procedures as well as techniques, but the procedure comes first (Boeing probably says it is ok to call V1-5 or V1 which shows they approve of SOP being both ways) THEN the operating technique.
 
Bumblebee said:
apparently it was during the emergency avoidance, and there is some gray area as to performance...or isn't there? I thought you just said that there are times when, on the Command Authority of the PIC that you could take off before or after V1. So the discussion about safety of a V1-5 is dumb because a captain made an emergency decision that worked out.
Click to expand...

I really wasn't sure what you were saying with that post.

Yes, there is a gray area to performance. When you have to deviate from SOP such as rotating before or after V1 like the incidents I shared understanding that the performance is gray is important.

Finally, yes, calling it at V1 or V1-5 works. I would say though there is probably more danger of initiating a RTO at V1+5 than rotating at V1-5 (and obviously initiating a RTO at V1-5). I like how we do it calling it at V1-5, but calling it at V1 really doesn't matter in the grand scheme of things.
 
Derg said:
Not ours. The school of thought at my company is that once you reach V1, the decision to take off has been made as in the "takeoff decision speed" is somewhat mislabeled.

@PeanuckleCRJ is an instructor so please feel free to steer me if need be.
Click to expand...

Most airline captains are trained that once you hear V1 your hands come off the thrust levers to help reinforce the fact that you are going and you don't initiate an abort above V1
 
Seggy said:
Nope, still not buying it.

When Boeing/Airbus puts out an aircraft they don't give the operator techniques to operate the aircraft by. They give them procedures. Airlines adopt the procedures to fit their existing operating procedures. Yes, airlines have different procedures as well as techniques, but the procedure comes first (Boeing probably says it is ok to call V1-5 or V1 which shows they approve of SOP being both ways) THEN the operating technique.
Click to expand...

Of course they don't give techniques. They give procedures. But with a technique being a "method to accomplish something", that's where a procedure comes from......normally a single technique that's tested, accepted, and adopted as a single-method that's accountable. That's a procedure, such with what your company uses that you described. There's no allowance for doing anything else. By the same token, as you say, a procedure could also beget different techniques for accomplishing them, but they have to work towards the same end-state, such as the example you give.
 
Just face it Mike, airlines are use different procedures for their V1 call outs, not techniques.
 
Seggy said:
Just face it Mike, airlines are use different procedures for their V1 call outs, not techniques.
Click to expand...

They do use different procedures, not arguing that. Those procedures came from somewhere, the singular method didn't just appear from thin air. A technique....a way to accomplish something....was tested and accepted to then become that airline's procedure. A different airline chose a different methodology for their procedure, or maybe use the same, in order to establish their procedure.

We're kind of arguing the same thing.
 
Techniques are derived from and support procedures.

Not the other way around.

You can have a different procedure that fits your overall operating principles. You don't have overall operating techniques.
 
Seggy said:
Techniques are derived from and support procedures.

Not the other way around.

You can have a different procedure that fits your overall operating principles. You don't have overall operating techniques.
Click to expand...

This is true.

By the same token, you have to have techniques as methodology to accomplish a particular task. To create a procedure, or a singular accountable methodology for accomplishing a task, different ways or techniques (ie options) are usually tested/evaluated and the best one selected to become a procedure. The procedure came from somewhere, it didn't just all of a sudden appear as-such and be accepted as-such automatically.

The two operate interchangeably in ways.
 
You must log in or register to reply here.
Back
Top