Expeditedescent
The answer is .... it depends.
For example if I issue a new climb/descent clearance and the previous one had a level restriction, then yes, the previous restriction is cancelled unless restated (see MATS Part 1).
But if I simply put the aircraft on a heading (but don't touch the vertical element of the clearance), then I would expect the restriction to be complied with. The pilot should still have some idea of the location of the restriction point and arrange the flight to meet the restriction abeam it.
The difficulty you cite in the WELIN case is probably related to the Flight Management System. The pilot will have the original restriction for HEMEL programmed in, however as soon as he executes the route direct to WELIN then
ALL previous waypoints are erased from the system. HEMEL simply ceases to exist as far as the aircraft and the pilot are concerned and the restriction will drop out of the FMS. In this case you could argue that he will no longer be crossing the restriction point (even if in reality he does as near as damn it) and therefore the restriction is void.
The company notice about any new clearance cancelling ALL of the previous one is not in my opinion correct. It should only override the revised elements, i.e if I give a new level instruction, it doesn't cancel the previous route clearance does it ?
------------------
10 West
UK ATC'er
[email protected]