The simple arithmetic for rail vs air for Exeter - London (city centre to city centre) has always been the downfall of air services to Gatwick, which have been run, on and off, since the 1980s, as it would be to any airport near London. London City is on the edge of that category; we'll see how that works out. It's easy for Canary Wharf, quite a long ride to the City, and even longer to the West End.
Even with short check-in and security transit times, the air service cannot beat the rail service on overall speed. It can of course offer much less expensive fares than the rail 1st class fare, even taking the rail element of the air journey into account.
Passengers travelling out of the UK an air service to a hub airport can create a demand, but either the sector yield is too low to be viable, or the sector fare is too high for the passenger, who can always get a bus or train instead to the hub airport if it's in UK.
Part of the rationale of the CDG route is to access lower-cost long-haul services, perhaps even short-haul services, from there. As the London airports get more crowded and thus too expensive for (passengers using) small regional airlines, this makes more and more sense.
By the way, the worst case departure from Exeter's 2083m was a DC8 going non-stop to Toronto. It was a terrifying event for those on board, as the aircraft slowly gathered just enough speed to make a full-stop a crash. Concorde's several take-offs were fighter performance by comparison.
Last edited by Capot; 23rd Apr 2014 at 12:44.