ATC IssuesA place where pilots may enter the 'lions den' that is Air Traffic Control in complete safety and find out the answers to all those obscure topics which you always wanted to know the answer to but were afraid to ask.
Inbound to London eg via GIBSO and then given direct GWC, does the "at FL270 at GIBSO" still apply?? Always meant to look it up but interested in an answer from a controller. Somewhere at home is a copy of CAP413....
Technically not. Can't give you the exact 'book' quote, but it's a case of a new clearance cancels a previous clearance & any restrictions unless otherwise reiterated.
It's only really an early morning thing, we'll always try to keep you as high as possible for as long as we can, and cut as many miles off a route as we can. At that time of day it's not a big deal if you're high, but I'd still always check when you're given the direct, just in case. In a stream if number one complies with GIBSO, and everyone else goes in high, all the lovely speed control fails rather quickly with the different level bands.
I was always lead to believe if you were going direct GWC about FL270 at GIBSO was roughly on the descent profile?
Thanks for the info. Just found my copy of CAP413 so will have a look in there too. Regarding GIBSO being on profile I don't know the direct distance but it is about 74nm on the WILLO STAR so it's actually well under.
Regarding early morning arrivals it's always nice to hear: "direct Mayfield keep high speed!".
The FL270 restriction at GIBSO is a relic of previous airspace sectorisation; it goes way back to when the descent point was 30 miles before SAM The current sectorisation could accommodate FL300 or similar.....an econ profile is probably low 3 hundreds. Precedent....FL140 at BEDEK, but no-one expects to regularly cross NUMPO at FL270 even though the distance is about the same. I believe that FL270 by GIBSO has many advantages for the HURN sector by allowing sequence/speed/integration with other traffic. An aircraft presented hot and high with a tailwind can be virtually uncontrollable. My PPRuNe buddies are correct when they state that a new clearance replaces a previous clearance with a proviso that any previous restriction must be repeated if it still applies. A changing traffic situation may not require re-application of the restriction.....or it may be evident that it will/has been complied with....or an individual co-ordination by the controller with other ATC sectors/units has been completed. [Many restrictions between sectors are called standing agreements and are put in place to allow vast amounts of traffic to pass through the system without individual co-ordination; when it is quiet there is more flexibility]
Just as an aside, surely if a a level restriction applies at any waypoint, and that waypoint is bypassed by non-published (i.e ad hoc) direct tracking, then surely prudence would suggest that any restriction should be restated with the clearance? At the very least 'track direct zzz, reach F... abeam yyy' ?
"a new clearance replaces a previous clearance with a proviso that any previous restriction must be repeated if it still applies..................................A changing traffic situation may not require re-application of the restriction.....or it may be evident that it will/has been complied with....or an individual co-ordination by the controller with other ATC sectors/units has been completed"
055166k, to add to your history lesson, when the inbound routes were changed off R8 to go south of SAM, the FL270 was kept due to the outbounds via GIBSO climbing to FL250, FL260 would be logical for the inbounds however this used to be the standing agreement for BB/BE/NX departures going south through SAM so FL270 stayed. It was only about 5 years ago the BB/BE/NX agreement was stopped!
Hempy, that is exactly what should happen if the restriction is still required.
As someone who would give you direct to GWC, I would not expect you to be FL270 at GIBSO, as it was no longer on your route.
What you'd get from me is the expect level at GWC of FL130 and a when ready down to FL270 to comply with the agreement between us and the next sector.
Direct to GWC is only really something that will happen if you're coming through first thing in the morning, ie arriving at GWC before 06.00z. After that it can become complicated with arrivals from the South and it all goes tits up for someone