Alternative clearance problems
During work yesterday, our sector had problems with aircraft of the World's favourite airline after issuing new clearances.
Several times, I and collegues were asked after issuing a new descent/climb/heading if the new clearance invalidated the old one.
Towards the end of shift, I had an A319 inbound to EGBB which was cleared as standard FL220 Level HEMEL. I put the aircraft direct to WELIN and the aircraft then proceeded to cross HEMEL at about FL250.
The change of track was not significant, only about a 5 mile or so shortcut, so it wasn't as if I gave a drastic turn.
On chatting with the pilot he told me that their ops dept had just issued some papers saying that ANY new clearance invalidates the old clearance COMPLETELY. So if you put an aircraft on a heading for example, then they assume that the previous clearance is no longer in effect, whether it contained a level restriction or not.
Now surely this has serious implications, after all how many of us have time to keep re-issuing the previous clearance when issuing a new one?
In these days of multiple sectors with vertical splits, the whole thing will fall apart if aircraft don't adhere to standing agreements, simply because they were put on a heading or descended/climbed etc.
Cheers
Expedite