Good trick in the Billy Boeing convayance (if your going to
be delayed for p.back) is to release the brakes after doors
close PROVIDED THE CHOCKS ARE IN. The box records the
time. I had a good record for "on time" departures despite
a "28 min taxy" to a runway only 5 mins away!
The Scarebus records time on departure to the actual
minute when the nose-wheel starts rotating (rounded up
to the next minute when over 45 secs) after p.brake
release with doors shut. On arrival it records to the
EARLIER minute. Want more time in your log-book? Delay
setting the p.brake till the clock ticks over 59 secs!
The more ways FMC engineers throw new ideas into the
plumbing for reduced timings (and therefore reduce your
flight pay) the easier it is to clog up the drains!