Traffic is,
Just a pilots perspective on this:-
When unregulated, airborne not before restrictions can be hugely frustrating, and can it can be felt that the CFMU system is not working as it should.
The truth is the system is NOT perfect - if it was overloads, bunching etc etc would not occur. What I do not want however is to get airborne and create one if it CAN be stopped by such a short term FMP restriction.
On restrictions such as this there is obviously a short term sector issue to be resolved. In the many hours I've spent over the years in Ops rooms taking an interest, there's not one LAS/GM who is there to create an issue, only to solve them. I firmly believe however it is the LAS/GM's DUTY to manage the SC's workload whenever possible.
So, how do they solve a short term issue? To my experience, and I'm not a controller (so happy to be corrected by your fellow colleagues!), reducing flow rate is not necessarily what will solve the short term problem. If a sector is running at say 42/60 and a short term issue is apparent, reducing via the CFMU to say 35/60 will probably not solve the problem, and takes some time to be apparent. The only short term measure is to do what you are experiencing, or apply an MDI. The CFMU is a primary form of system protection, but with it not being perfect, there is a need for secondary measures as well.
It is frustrating that these restrictions are not transparent, and yes your right, it also means that they do not then show against NATS statisitics. We're all under pressure, on both sides of the industry regarding on time performance/delays - that won't go away, what I am convinced of though is that operational staff are NOT puppets to pin stripe suit requirements. It's our licences - not theirs.
I understand that such restrictions place extra difficulties on aerodrome controllers, and that perhaps you feel your on the receiving end of the problem. I work from BB, with 33 deps that have only one runway line up point and single taxi-way serving it. The poor GMC given relatively short notice in a stream of outbounds can suddenly find the whole dep sequence stopped if subject aircraft is already in the taxiway stream. Very difficult situation for all!
Not sure how we improve the current situation, but open to suggestions?
Anyhow, enough rabbling - I'm sure the centre guys can give far better responses....
Keep it safe!
Rgds
30W