Thanks for the replies guys. I am going to write to my Chief Pilot (an ex ATCO) to ask him to review this aspect of our manuals. CA I see the time tolerance in Annex 11 but can’t find a reference to either two or three minutes. Pint of Guinness \ bottle of wine if you can help me out with that ?
confused_atco is correct, and his/her references are valid. Anything greater 2m 30s is three minutes for the purposes you are referring to. Applies worldwide, not just in the Atlantic.
The same logic applies to holding and adjusting speed to cross a waypoint at a given time. A sequencing instruction to depart a holding fix or cross a waypoint at, say 0030 means any time between 0029 30 seconds, and 0030 29 seconds.