Calling V1 Early
JT, Mutt, Smokey, Alex, et al,
Thank you for arguably the best discussion I have read on pprune. This is a fascunating issue and it is clear that there are lots of pilots out there whose knowledge of takeoff performance remains hazy to say the least.
Smokey said it all when he said BELIEVE THE NUMBERS. Don't attempt to second guess either the manufacturer's data or your company's Flight Ops/Performance people. Stick to your company's script and you will not go far wrong. If you are unhappy with the SOPs try to get them changed. In my flying experience (25+ yrs) your Chief Pilot will take notice of a well-argued letter on any technical/operational topic from one of his pilots. He may not agree with you but should tell you why if he doesn't. Remember the collective wisdom of the Flight Ops department is almost certainly greater than your particular hot topic.
For what it's worth, the biggest issue in any RTO is to get the MAX RETARDATION AVAILABLE. This means max reverse (a bonus on dry runways) consistent with directional control and MAX BRAKING. Boeing did a study some years ago on the amount of braking applied in RTOs by a range of pilots ranging from their own certification test pilots to the average line guy. It was interesting that the only group who consistently used the max braking available to them was the test pilot group. This is not surprising when we rarely operate our aircraft to the absolute max and we are conscious of hot brakes etc for the next departure. An old instructor of mine used to teach us to "Get your ar*e up the back of the seat" to drive this message home to us that we needed to STAND on the brakes. Nowadays you would need to check whether the RTO function of your autobrake system applies absolute max braking or whether max manual effort would provide a higher level. In any case your non-pnormal SOPs should cover this area.
The Boeing study referred to above was published in either the Boeing Airliner magazine of the IFALPA mag (or both?). If anyone can tell us where it can be found, it would make interesting reading for today's pilots.
John, a wonderful discussion. Many thanks.