Trim Stab...If we have filed a flight plan, which has been accepted and acknowledged with a stated cruise flight level, how do ATC justify holding us down at a lower level?
On more than one occasion, I have uplifted OPS-minumum fuel for the filed and accepted flight plan, then been held down below the planned flight level for a significant portion of the cruise meaning that we risk not having enough fuel for the flight. The answer is not - "you should have uplifted more fuel" - we fly to extremely tight margins and if fuel is more expensive at departure than arrival, we uplift the OPS minimums.
The whole point of OPS fuel regulation is that it should cover all forecasted eventualities with sufficient safety margin for safety - so how do ATC justify throwing a completely unforecasted spanner into the equation by holding us down below the planned flight level?
How does ATC "justify" it? How can anyone who flies not know the answer is "traffic"?
If your "extremely tight margins" don't allow you to "hope for the best, plan for the worst", it calls into question the viability of the operation itself. If saving 50 lbs of fuel is going to make or break the company then the real concern is how such a shoe-string operation can afford far more costly and more critical things like maintaining the aircraft to a safe standard or hiring experienced pilots who understand the difference between theory and reality when it comes to flight planning.
In the future, you should apply real-world aviation experience to your operation's fuel-figuring and (that's right) uplift more fuel. It sounds like the policy (or the person driving that policy) itself is flawed or not well-versed enough if it/they ignore the world of ATC delays/changes etc. They are as much a fact of aviation life as dynamic/unforecast weather situations, blocked runways, State aircraft showing up, aircraft in distress, etc, etc that can force delays that require more fuel than what your planning program includes. A couple bingo-fuel diversions in a year will blow any teacup-fuel savings you think you're realizing by flying around in a potential pan-state all the time.
In the meantime, unless you've stated to the controller you can't accept a speed/altitude assignment or its been given at pilot's discretion, you're obligated to comply promptly, not "
as tardily as you think you can get away with". Your faulty planning or erroneously thinking yourself unique in the cause to save fuel/money for your operation does not justify unprofessional behaviour in the cockpit.