For a time, ATC at Stansted allowed us to fly 170 to 5, yet it was scrapped.
Yes it was a trial that was never adopted. The 738 works lovely at 170, but 160 requires the gear down/F15 so not fuel/noise efficient at all. There is nothing to stop you requesting '170 to 5' on first contact with Essex for STN which I'm more than sure they'll accommodate when they can. I do it regularly with LTN (request on first call with LTN Director) as based there, and have always had it accepted
Technique we mostly use. 160 F2 (watching ND to see how quickly to achieve it....If you are already 2.5nm behind when told to reduce - Speed back quick!)
I'd suggest just flying the allocated speed as promptly as possible on all occasions and not second guess compliance promptness based on TCAS seperation with the one ahead. Whilst 2.5nm is the MINIMUM, Wake Vortex seperation from the one ahead may well demand a greater seperation than that. The requirement to report aircraft type on first call is so they can confirm that the wake seperation they apply is legal. The final approach seperation is ATC applied in accordance with the rules, they're bloody good at it and LHR are abosolute masters at it
- no second guessing or basing speed reduction on TCAS from us - just do as we are told and the system works extremely safely and efficiently
