It is good to have these debates, its really the only chance we gave to talk to crews. Its hard not to get spiky and defensive though
. I guess I've confused the issue by discussing the feeder fix time, which is different to CTMS/PTL. CTMS is s strategic device to match demand to availability using ground delays, whereas FF are a tactical tool to achieve sequencing.
Continental-520 - the short answer is its better than doing nothing, and it solves more problems than it makes.
Originally Posted by Continental520
a) there is no way for the controllers to easily know/incorporate each aircraft PTL into the job
Every aircraft arriving during the holding period (after departure from inside 800nm ) is required to obtain a PTL beforehand. So every aircraft is known by the system.
The 'system' in this case is an excel spreadsheet on a PC in CB, not connected to TAATS in any way. To be honest I don't think it occurred to any of us that monitoring compliance was going to be necessary. (Also, the way I read the NOTAM, its ALL scheduled ops, and non-sched depatring within 800nm.)
b) The system is designed outside most aircraft capability in that it requires 'to the second' accuracy, and creates a '30 second early/late' type error
Thats a FF issue rather than PTL, my fault. The one specific case of two aircraft in trail adjusting their own speed is less efficient and safe than us assigning speeds and/or vectoring. It does explain why sometimes you will get a FF, and then a vector/speed at late notice. Also bear in mind that the people designing and pushing to implement these procedures don't work traffic and don't use them, but that our problem not yours.
if 40 kt faster will keep spacing between me and the one behind, why would the same controller slow me down 10nm earlier when the preceding traffic is faster?
Aircraft in trail on descent at the same speed will, overall, close up. Speed reduction isn't linear though, especially with different profiles eg Airbus vs Boeing, or domestic medium vs intl heavy. You can watch the speeds swing between some closing, some opening, some closing, lots of closing, oops! Now consider a chain of 5 or 6 aircraft doing the same. By slowing you down the controller may have solved one problem and made another, thus requiring an increase later.
Alternatively, they may have just made an error. Monday lunchtime a 717 was given a FF/250kts - cancel FF - max speed cancel speed below 10 - reduce to 230kts, while a turboprop received hold- cancel hold turn inboud now profile speed - orbit -FF/220kts. Not even I an going to try to defend that!
willadvise - (cough)fokker conspiracy(cough)
Edited to add : two interesting quotes from the airport master plan,
Annual aircraft movements are forecast to increase from 107,000 movements in 2008 to 170,000 movements in 2029.
It is considered unlikely that any of the runway developments will be required during the 20 year planning period of this Master Plan 2009.
