Yeh, what you say about Va is true for light aircraft.But such a figure doesn't exist for a 767.Whenever the word manoeuvre is used it refers to the minimum speed for a given configuration.

Hi,I am sorry to point out a different point of you regarding to your own experience, but this is the rule applying for all JAR25 aircraft.To my knoledge, the 767 for example is a good old JAR25 bird.Know this kind of calculation speed is not provided to pilot training on the aircraft, but designed by the constructor of the aircraft, tested in a wind tunel and by the test pilot during the test campain.You will never see a 767 flight instructor who is going to teach you this, cause unless he is a test pilot, this nice to know and not need to know cause most of the time you wiil be flying using the FMC precalculated speed, and the computer knows much sharper than us how to calculate all thos speed and is programmed with all the common Bernouilli and Laplace lows, as well as Va, Vb, Vf lows.What I just want to say, it is something that is the matter of aircraft constructor, aircraft designer/engineer, and test pilot. I am not even sure this is part of the FAA ATP. But this is part of the French ATP under aerodynimics section, and it is a big big piece to obtain the f....g french ATp, beleve me... (went through it several times)With great respectvery best regardsCpt Cyrille de Lattre

Well the quoted figure of M.78/290KIAS is turbulent air penetration speed. I would regard this as Va. Whenever turbulent gets to moderate or worse, we slow down to .78 (or 290). Iz

I dont doubt that during the certification of a new aircraft all this is looked into!But from a line pilots point of view its not information we have.We have the minimum manoeuvre speeds, and as mentioned below the turbulent air penetration speed.

If you guys don't mind, I'd like to talk about this subject on the "PPRuNe" website (mentioning some of the things that have been said). The more experts we have in this debate the more we have to gain :-hah (maybe).Cheers.Ian.

Hi,This is not Va, this is the Vb, but most of pilots are by "language abuse" calling it Va. As soon as you are speaking about air turbulent penetration speed with a JAR 25 bird, as a purist, this is Vb.Cpt Cyrille de Lattre