737-200 V1 cut

[AirRabbit]

Nicely Said JT!

JT … a very reasonable synopsis of what’s been posted … as usual.

The document that’s been referenced now several times, the Takeoff Training Safety Aid is a 300-page document that does essentially recap most of the original concerns, took into consideration a great deal of the takeoff accidents / incidents (both rejected and continued takeoff) and as we’ve pointed out, that group completely understands the desire to ensure adequate amount of runway remaining in case an RTO is chosen … but they acknowledge that should something else happen (I’ve used the term “abort-worthy failure”) immediately or within seconds of that now-reduced speed call-out, the decision will have become much more complicated to address. Because there was apparently very vocal groups wanting to push for one or another of the individualized approaches, the task of the folks running the effort AND the airplane manufacturers – who were on the “hot-spot” for making the data available and ensuring its accuracy – the result was the “kinda-sorta” two-point description of this “mysteriously defined” speed called “V1” … that says the following:

First, V1 is the maximum speed at which the rejected takeoff maneuver can be initiated and the airplane stopped within the remaining field length under the conditions and procedures defined in the FAR’s. It is the latest point in the takeoff roll where a stop can be initiated.

Second, VI is the earliest point from which an engine out takeoff can be continued and the airplane can attain a height of 35 feet at the end of the runway.

The way I’ve always described the V1 speed importance is to say that the pilot flying has to be ready to abort the takeoff if or when he/she deems it appropriate to do so. Once the power is advanced and stabilized and the brakes are released (normally these things are accomplished simultaneously) there are only two(2) actions that the pilot performing the takeoff can take:

1. reject the takeoff; or
2. continue the takeoff.

The pilot flying may, in his/her own consideration of any possible problem, reject the takeoff at any time UP UNTIL the other pilot says V1, at that point and forward the takeoff is to be continued. In other words, the so-called “decision” is being contemplated from brake release until hearing “V1” – at that point there is NO decision, if the pilot flying had not already initiated the RTO, he/she is now committed to continue the takeoff. That specific speed has been colloquially referred to as “the decision speed,” when it is probably more accurate to colloquially refer to this number as “the no decision speed,” since the decision will have already been made. We shouldn’t have to get wrapped around the axle in trying to determine what that speed actually means. It’s been defined. It’s been described. It’s that we have apparently done a poor job in making line pilots understand the correct meaning of the term.

Perhaps what we should have been saying is ... the pilot flying may decide to reject at any time up until he/she hears “V1” called out, from that point forward the pilot flying is committed to completing the takeoff. If the pilot flying initiates the abort procedure (moves the throttles aft; steps on the brakes; extends the spoilers, or any combination) before he/she hears the other pilot call out “V1” – the airplane should have sufficient runway to safely stop. IF the pilot flying slams the throttles shut and does so simultaneously with the other pilot calling out "V1," we would see the penultimate example of the absolute latest point at which the RTO can be initiated - and it WOULD have been initiated ... in that the throttles were closed - there are no "do-overs" - the airplane is stopping! Observing the penultimate example of the earliest point at which the takeoff is committed, by definition, is not likely to be able to be observed, because there is no observable action that the pilot flying would take to “continue” doing what he/she had been doing from the initiation of the takeoff roll ... the only "observable" action would be to observe the pilot flying taking "no action" as the "V1" callout is made.