This guy posting on the BBC web-site found the solution - or maybe not
"Most air travel is unnecessary, holidays can be taken in the country of origin and many business meetings could be held by video conferencing. We should consider a permit to fly similar to the permit to travel required during the second world war. If passenger numbers were substantially reduced then a much higher level of security inspections would be practicable. Terrorists would have the double deterrent of obtaining a permit and passing tightened security."