With air resistance proportional to the square of speed, a 1,000kph airliner needs 10 times more energy than a 300kph high-speed train.
So aviation can never be green or sustainable if alternatives exist – or if engineers can build them.
In this context, UK transportation policy should be clear. Build high-speed lines linking to HS1 and the wider European network to replace short-haul city-to-city flights. Build high-quality orbital rail links to Heathrow to eliminate feeder flights to intercontinental routes. Then bin the whole policy of aviation expansion.
"Green" aviation is concentrating on the routes for which it is necessary, while leaving other routes, less damaging modes such as rail. This is the sustainable transportation future to which all engineers should aspire.
Good engineering is all about developing the right long-term solution – and hopefully earning public respect.
No responsible engineer should contemplate doing anything else.
COLIN ELLIFF (M), 20 Hartley Road, Harrogate HG2 9DQ