I know it's slightly different but I've been meaning to ask - when ATC says "Hold at XXX, expect to depart XXX at XXXX, speed reduction approved.", is there any limits to the speed reduction?
Heard some ATC cracking it the other day because a 737 slowed down to 215KIAS and "that if you are going to slow down that much you have to let us know." Huh? Since when?
grrowler.
In this situation I think the controller should have been more careful. Once I slow an aircraft down like this I will either ask them what the are going to reduce to or descend them to avoid any following traffic because I am amazeded at how slow you can go sometimes. In saying that if you are aware there is an aircraft behind you, a call saying that you are reducing to x kts/mach can't hurt.
I'm very out of date here, but, from memory ....
Companies have Letters of Agreement with Airservices detailing a lot of stuff, including performance figures.
ATCs are trained in line with those agreements.
If the general performance figures are changed, the Company is expected to update the Letter of Agreement
Speeds entered into the flight plan are not entered into the software that ATC use???? I think.
So, obviously ATCs are expecting certain speeds. When they don't happen ...
Peuce et al
MATS currently details maximum cruise speeds for each company aircraft type and typical/maximum/minimum speed for approach and climb. There is no agreement for cruise speeds and the approach speeds are not mandated.
Speed entered into the flight plan is entered into TAAATS and estimates are calculated using the information.
The difficulty is 2 fold
1) Some enroute sectors operate with TMA strips which don't show the planned cruising speed and hence can't change the speed if a pilot advise them of a change. The only way for these sectors to see you planned speed is to open the flight plan window and check it which is time consuming for the short haul radar sectors.
2) There is a huge variety in flight planning accuracy and compliance with flight plan speeds. You soon learn that what is flight planned is not flown 50% of the time. There are any number of reasons for this eg schedule, wind different to forecast, use of a standard plan which is not updated to reflect current conditions, pilots not knowing what speed they have planned (or had planned for them) etc. Some operators will plan a change of speed with a change of level which is not requested. Some operators will plan a level and approach speed at a waypoint near the aerodrome, some will plan a climbing speed on departure which doesn't reflect cruising speed. All of which has ATC's very sceptical about planned cruise speeds. The upshot of all this is that if I am going to run you close together I will ask your speeds everytime even same type and same company. Gone are the days of you could rely on the plan or typical cruise speeds.
A comment on low and slow. If you are in a 73 and have planned F240 .64 I am likely to think you have a pressurisation or engine problem that precludes operating at normal speeds/levels.
As for sequencing you sometimes will end up with the rough end of the pineapple but I have seen it the other way. Ie I have watched someone flog it the whole way across the bight vs someone taking it easy. The first aircraft copped 15 mins delay due traffic, undoing anything time he made up and the second was naturally at the end of the sequence and had no delay.