Leave XXX heading....
I operate into & out of LHR on a regular basis where we are almost always asked to leave which ever holding fix on a heading. Normally we preselect this heading & when we are directly over the fix heading engages automatically or we engage it manually. The heading change involved is not usually a great deal & of course the TAS & hense the radius of turn is fairly low. ATC seem happy with this technique of turning when we get to the beacon.
However I was recently asked to leave an airway fix on a given heading which involved a turn of about 60 degrees. I used the above technique but with the higher FL & TAS the radius of turn was significantly greater. ATC queried whether we were indeed leaving on the given heading.
In this situation what do ATC expect:
1) Fly to fix then turn.
2) Turn before beacon to leave as if we had flown overhead on that heading.
3) Split the differance.
4) Something else.