speed control on final
I'm getting a bit concerned with aircraft slowing down on final approach without being instructed. this can be in the form of reducing below 160kts before 4 dme, or reducing to 160 from 180 when established on the ILS.
In the last two days I've had three aircraft reduce to 160 before instructed.
First time the vortex gap was eroded and I had to break off the following aircraft and reposition. Thanks to the profesionalism of the lufthansa pilots behind we didn't lose any aircraft movements/ miles on the approach, but still a lot of work for me and therefore all the other aircraft on frequency.
Second time the aircraft increased speed again. This made the spacing difficult for the tower controller to judge so they didn't line up a departure. That means every departure at the holding point was delayed for an additional 2 minutes as the airport lost a movement.
Third time I had to take the following aircraft through the localiser then back for a shorter final than expected. again a huge impact on workload and RTF congestion.
Apart from the vortex erosion these incidents were not really a safety problem, but they could have been.
I've had a dozen of these incidents in the last year and almost half infringed vortex or standard separation. The most serious of which I was suspended from radar until a brief investigation was complete. All because a pilot didn't follow a clear and unambiguous instruction which had been read back.
I try emphasising "maintain 180kts" when clearing someone to descend on the ILS, although I feel the last assigned speed should be flown until instructed. (The extra two seconds to say "maintain 180kts" can mount up for 40 aircraft an hour.)
There doesn't seem to be any pattern in the airlines or fleets that are guilty (or nationality, these last three were british airlines and crew)
So what can I do ? increase the spacing (and therefore delays)?
MOR each aircraft that slows down ?
Shout at the pilot at such a critical phase of flight ? (I don't fancy being on a plane being landed by someone who has just had a bollocking)
This always appears to me a terrible breakdown in CRM, after all you wouldn't dream of changing a heading or level without instruction (or at the very least asking first) so why ignore a speed instruction ?
Sorry about the moan, the professionalism of aircrew flying into London airfields is generally fantastic, I'd just really like to know why tis happens and how to stop it happening again.
Phew, glad I've got that off my chest !