While flying BA155 (currently operating to a revised timetable) LHR-CAI yesterday I got to thinking - given that aircraft supposedly make their money while in the air - how incredibly inefficient this revised timetable is vis-a-vis time spent in the air / time spent on the ground for the aircraft.

Using published (as opposed to actual) flight times and letting:

A = LON-XXX flight duration
B = XXX-LON flight duration
C = duration on ground at XXX

and calculating the aircraft utilisation efficiency (let's call this 'E') as:

E = (A+B)/(A+B+C)

for BA155/BA154 LHR-CAI-LHR

A = 4h 40m
B = 4h 55m
C = 12h 5m

yields an E value of 44%.

In other words, well under half of the overall LHR-CAI-LHR journey time is spent in the air (in reality it's probably closer to 40%).

Any nominations for a route with a lower 'E' - and for the highest 'E'?