Is V1 called 'Decision Speed' or 'Action Initiation Speed'?

[john_tullamarine]

HN39, an extremely pertinent observation, good sir. I would entreat you to reinstate it for the benefit of the readership.

[HazelNuts39]

Thanks John,

I withdrew my remark because on reflection is wasn't entirely pertinent and didn't add anything to what had already been said better by other posters.

[LeadSled]

Multiple main gear tire failures.

Aviatorhi,

No way, a lot of people died in Spain when a pilot did that (nose gear tyres, in this case)

This is too critical a matter for any pilot who is actually flying heavy transport aircraft (FAR 25 or equivalent) to be any doubt, please do not read the manufacturer's description like a bush lawyer, the definition ----- and what you have to do if you are confronted with a potential go/no go decision must be clear and simple.

The reason V1 is not a "decision speed" is that the decision must be made before V1, think of V1 as the speed at which the takeoff must be continued if the abort has not already been commenced.(That's how Boeing describe it, in an extensive discussion paper on the subject)

Don't get all tied up in in certification standards, if you are the pilot.

In the case of an abort, or continuing the takeoff you have to keep things very simple.

Some time before V1, something has happened and you decide it is important enough to abort.

or

Something happens so close to V1, that it is going to be passed before any reject action, so you must continue, unless the failure is so severe that the aeroplane will not get airborne and fly.

Boeing (and, no doubt Airbus) have excellent training material on the subject, the words used may seem different, but the "definition" of V1 should be clear, you can't start making the decision at V1, you have either commenced the abort by that speed, or you go.

The 2 seconds doesn't belong to the crew.

FE Hoppy,
That is correct, very correct, the 2 sec. is a matter for performance engineers preparing takeoff data.

PLEASE, PLEASE don't any of you who are actually flying these aircraft think you can commence an abort 2 seconds after V1.

If you think otherwise, you are misinterpreting something that that must be very clear in your mind.

[john_tullamarine]

hear ! hear !

[good egg]

High Time to Redefine V1

Having been preparing a paper on windshear I noticed this link referring to V1...

http://flightsafety.org/asw/jul-aug1...23-24.pdf?dl=1

Any comments?

[HazelNuts39]

High Time to Redefine V1

The title had me a little bit worried. But then the author doesn't really want to change the definition of V1. All he wants is a descriptive name for it, to replace the misleading name 'decision speed'.

In that respect, I agree with Vilas in post #34. However, it is not a very good name because action to stop can be initiated at any speed less than V1.

If one wants a really short name, I would suggest 'go speed'.

[tommoutrie]

Its called V1. It means we are continuing the take off. Maybe it used to be called decision speed because you've already made the decision. But once V1 is called, you have made the decision to continue. If you have made the decision to stop but happen to be so close to V1 that your reaction time means the aeroplane accelerates through V1 before the application of brakes and closing the levers etc starts to have an effect, you are stopping. Thats because you made the decision before V1. Lets call it Decision Made Speed! You'll never get a bunch of manufacturers to agree what to call it but as long as we know what it means, who cares? Short is good, lets go with HN39's idea of go speed.