Hi Knold and Baggy,
Ok for the time being I wont mention noise on this debate again but I want to concentrate on the FLEX T/O.
If taking off from a not limited rwy with an ATOW of 60.000 kg at sea level and 15ºC using standard flap setting (11º)
we have:
V1 - 130
Vr - 136.5
V2 - 145.5
but if the temperature is 50ºC we must add 4 and 2 knots to the V1 and Vr, hence
V1 - 134
Vr - 138.5
V2 - 145.5
These figures are from the AOM, and I think the reason why captains add those knots when flexing is behind this temperature correcction.
But again, if taking off from a hotter airport the engines are developing less power and we will need more rwy to reach the same speed as if the temp was lower. Also, if we take into account that the speeds used are IAS we will find that the TAS (which is what it matter to stop the aircraft) is higher with higher temp. ¿correct?
Same thing if we take off from a higher field, knots are also added to V1 and Vr. but lets just concentrate in the temperature increase.
Could you please check your AOM for a situation like I have mentioned. This will help me to undestand a bit more why captains vary the speeds when derrating.
I might going a bit too far, but I believe that I can only solve my doubts within the pprune community.
gracias chicos.