Apologies for the delay in answering....... Needed to pop up to the local pub for a Guinness.....
Hudson,
With the introduction of our new fleet aircraft a couple of years ago, we had two schools of thought in relation to the V-speeds at actual temperature. Some wanted to use the convoluted method that I described above. They justified that with the argument that if you satisfy all of the takeoff requirements at 70T, the surely if you use the same takeoff thrust at the lower weight of 45T with the higher V-speeds, you will reach the V1 point sooner with a greater distance to stop and with less mass to stop.
Is this safe?? We couldn’t find any regulation that said that it wasn’t.
Is it prudent?? We operate in an environment of excessively long runways with severe Temperature inversions (+15°C) during the summers. Some felt happier taking the extra speed into the air. Using the higher V-speeds introduced the Boeing philosophy of Improved Climb (Airbus Over-speed.). The extra runway length was traded for greater climb performance.
Your situation is totally different; I seem to remember that you or someone else mentioned using a takeoff flap setting of 25 for takeoff from those atolls. If this was the case then keeping the aircraft on the ground for that extra 15 kts totally defeated the purpose of selecting the higher flap setting!
Some may argue that you should never have a higher V1 than absolutely necessary, but considering that we are using Balanced field V1s, Optimized V-speeds, Improved Climb or even just rounding V1 up to Vmcg. You may find that its an everyday part of our lives.
Mutt.
