I must be getting old. In all my years I have only ever been interested in 3 things during the takeoff roll:
1. Runway centreline;
2. IAS; and
3. Engine EGTs.
So, in answer to any question about the wind vector during the takeoff roll, my answer must be "what wind vector?"
The IAS indicator will tell me anything I need to know about windshear. I don't care what the wind is. If the IAS is telling me the aircraft can't fly, then that means stop. If the IAS is telling me I can fly, and there is insufficient runway to stop, then I go. The wind might be 50 knots on the tail. I don't care. Letting a wind vector influence your stop/go judgement is asking for trouble. The aircraft doesn't care about wind, it only cares about IAS. It's IAS that makes you fly (or not), not wind. And it's the EGT's that will keep you flying... There is
nothing else in the cockpit that is of any interest during the takeoff roll.
Funnily enough, Boeing don't make any mention of the wind vector in the windshear section of their manuals either. And windshear is not the only potential cause of slow acceleration: sticking brakes or incorrect takeoff data could be other examples. Only your IAS will tell you if you have slow acceleration, regardless of the cause.
So, eyes off the wind vector and back to the IAS/EGTs where they belong please folks...
