Time for the next summary ... and the thread is developing very nicely, I believe.
(a) the detail of the certification basis for V1 has evolved over the years and can be studied via the reg changes and the flight test guide for those who are interested (FAR25). That is, V1 for a B707 means something a bit different to what applies for the latest offering from the OEMs.
(b) early aircraft are PARTICULARLY accel-stop critical on limiting runways. Effectively, there is near nil room for the pilot to think about what he is doing at the time .. lest he desire a near guaranteed overrun.
(c) amendment 42 addressed a gaping deficiency but is not the comfort zone which some might suppose. Consider two (2) seconds at, say, 150 kt .. equivalent to around 150 metres (if I have my conversions lined up correctly). That's still around 500 ft (in real numbers) but not very far in real runway eaten up at V1 terms .... so one needs to be very focussed.
(d) "V1 is the speed where the first actions to abort the T/O should be initiated" ... NO. He who follows this point of view sets himself up for needless excitement. As a general rule, if it isn't already stopping by V1, then it's going .. especially for the earlier aircraft.
(e) it is a lemma that the calculations are only as good as the quality of the information fed into the sums.
(f) it would be nice if pilots knew all the ins and outs of the basis for performance calculations. Unfortunately that is unlikely ever to be the case. Some of us, either due to interest or employment, end up with a bit more knowledge than most pilots. Mutt, for instance, is an experienced operations engineer rated on most (and possibly all) of the aircraft for which he crunches the numbers. Centaurus, while having a piloting background, possesses a knowledge base on this subject far greater than the great majority of pilots. I would suggest that, in respect of his reference to "V1 - 15", he is probably suggesting that he starts to become GO-minded at that delta.
(g) for the accel-stop manoeuvre, the brakes MUST be full deflection (assuming the Type has anti-skid) until the aircraft HAS stopped ... one needs to be VERY careful about releasing any pressure until the aircraft has actually stopped. Human estimation of speed under significant acceleration is not good.
(h) the point about AEO/OEI is very important. Other than for some later aircraft, all the accel-stop data is predicated solely on a fuel cut failure at the scheduled speed .. which history tells us is not the usual case facing our hapless pilot during the real world event.
(i) query ? FAR 25.109 appears not to support the contention that "the JAR accelerate-stop definition differs from the FAR definition in that the JAR includes the stopway in the calculation, whereas the FAR determines that the aircraft will stop on the runway itself". Perhaps the poster might give us some further guidance as to the origin of his assertion ?
(j) for those who might seek to develop their own techniques, it needs to be kept firmly in mind that the CVR/DFDR history on most modern aircraft may just bring you unstuck at the enquiry ....
Ref (i) I have now had a chance to search for the AIC referred to and cannot find a link to it. Can the poster provide one, please ?
Last edited by john_tullamarine; 31st Jan 2006 at 03:59.