Speed Control Non-Compliance
I know this has come up on previous threads but it's caused me issues on several occasions this week and it's really starting to bug me.
Why do pilots have such issues complying with a speed restriction? The below is an example of an exchange I've had multiple times this week:
'ABC123 Descend (from cruising level) when ready FL180 level by xxx, speed 280 knots or less'
Pilot reads backs correctly and does not start descending for another 10-15 miles.
On passing around FL230 I check the Mode S which shows me an IAS of 305 knots so I quiz the pilot politely.
'ABC123 Just confirm you're doing 280 knots?'
'Affirm, 280 knots ABC123'
'ABC123 You're Mode S is currently showing 305 knots....reduce to 280 please'
'Errr, oh yeah, err sorry just coming back now'
At which point the longitudinal separation with the aircraft ahead has been massively reduced.
I know aircraft need to fly a minimum speed in order to keep up a sufficient descent rate so they can make restrictions especially if the descent clearance or speed restriction has been given late, but in all these situations the descent and speed was given on first call and the pilot did not descend straight away. Plus on questioning there is always a sheepish excuse for non-compliance (I'm guessing the fact we have Mode S is often forgotten).
A speed restriction is a form of separation! It is not given out willy nilly for a laugh! Pilots wouldn't dare not comply with a heading or climb/descent instruction, so why is speed not treated the same? I mean if you're out by +/- 5 knots then fair enough I can deal with that, but 25-30? No excuse. If you genuinely cannot make the level with that speed, then tell me! And although I might think you're talking crap I'll come up with an alternative plan without a single complaint. Don't just speed up by 25-30 knots and hope I won't notice. At the end of the day it's your safety that's being compromised, not mine.
It's becoming more and more common and if I'm honest I only ever have this problem with UK airlines. Really starting to bug me!
Ok rant over, thanks for listening.