Originally Posted by
florens
Sorry, I always thought there was a difference between an orbit (either lefthand or righthand turns) and a holding pattern (at least there is one technically, since there is no entry for an orbit). I agree that an orbit is a form of a holding pattern (not in the strict sense though), but it is a different procedure, that's why I made the difference.
There is a difference, an orbit means a 360 degree continuous turn "on the spot", as opposed to a hold which is two 180 degree turns with 2 minutes level flight in between.
The exact length of the level flight component of a hold is dependent on the altitude and clean speed requirement of the aircraft. It's not unknown to have a 5 or even a 10 minute leg, if it's at a particularly high altitude or it's known the hold will be particularly lengthy (since you consume more fuel in a turn than level).
My ATC friends have long remarked that Heathrow is working at its best if there's always one aircraft in the holds/stack, since it gives the Intermediate controllers maximum flexibility with sequencing. This is how you perceive the orbit on arrival, you enter the stack (having been told it'll only be once around) and then shortly after are told to exit the hold on a heading (before you rolled out of the first turn), thereby completing the "orbit".