The keeping of a time reference within +/- 30 sec relates to the accuracy of the timepiece used. It's not a navigational tolerance.
There used to be a reference to +/- 2 mins for navigational accuracy. Bear in mind this applied to when ATS must be advised about a changed ETA. There was no suggestion that it was a time-on-target requirement.
Last edited by Tinstaafl; 30th Jul 2004 at 00:05.