Ah, a local question! Devizes is only 8 miles from here and is either under or close to military airspace. To answer your question, I'd have to then kill you! Only joking, but I did see several more planes today over Westbury. Usual summer parachute jumps I think.
I'm only a novice at this so somebody might like to correct me... but here goes. From Gatwick flights seem to fly towards Southampton and Exeter before turning right and heading up over North Devon and towards Ireland.
From Heathrow, due west along the M4
, over north Bristol, and along the South Wales coast.
Bristol to the west join the M4
corridor, somewhere near the Severn Bridge.
From South Wales you either head westish towards Cork or northwest towards Shannon. There's a weekend track north-west from the Swindon area towards Dublin.
If more northerly tracks are used then either fly up the M1 (from LHR
), M5 (from BRS
), out over the Isle of Man, or even further north still. Flights to NYC would tend to take the more southerly ones; LAX
flights more northerly (think great circle mapping).