feeder fix time/ required time of arrival (RTA)
Quite often ATC will specify to cross a waypoint at a particular time.
How accurate must the aircraft be crossing this fix ?
Is within +/- 30 seconds good enough ? (considering that our timepiece only needs to be accurate to within +/- 30 seconds)
Some pilots aim to cross exact on time using whatever thrust/speed brake to make it happen whilst others happily accept anywhere within +/- 30 seconds.
Any ATC care to comment ?