16SidedOffice wrote:Acey91 wrote:Any insight into the calculation of the arrival rates on the OIS page?
A basic idea is that it's based on a combination of weather (not just local, but also out in the vicinity of the STAR's), staffing, equipment outages etc. Physical runway configuration as well. Correct me if I'm wrong but YYZ's E/W parallel's being so far apart they are able to run independently of each other which increases their rate over the others whose parallel's are MUCH closer together.
All 4 airports have runways that are sufficiently spaced to allow independent simultaneous operations. (4300ft or more spacing in between centerlines)
YYZ does so everyday, which explains the high arrival rate with two runways. It also has a third parallel entirely dedicated to departures and also has the right to apply 2.5 nm spacing on final, two things that increase the AAR.
YYC supposedly has the LOC monitor position, something that is required for independent sim approaches, but somehow i doubt it will be used much, especially with their staffing situation as described above.
YVR i'm sure uses independent approaches when the traffic warrants.
YUL, on the other hand, does not, nor is there a LOC monitor position avlb. Meaning the best YUL can do (in IMC of course, which is what those rates listed represent, at least for YUL and YYZ) is 36 arrivals/hour.
The reason for this is three fold.
First, as discussed, dependent simultaneous approaches are used, meaning a 2 nm staggered final, as opposed to the side by side operations at YYZ, YVR and potentially YYC.
Second, 24L being the primary departure runway at YUL, and the fact that landers on 24L often need to exit at the end (lack of dual taxiways) or backtrack to take the exit for the GA, tower requires a 5 or 6 nm in trail spacing on 24L.
Only GA and traffic headed to the domestic pier (with request and approval) can land on 24L, further restricting the use of that runway. Add to that the fact that YUL sees a lot of heavies (compared to say YYC), and the rate is pushed down even more due to the increased spacing required.
Third, and as I was saying, lack of dual taxiways and proper high speed exits. I know YUL did trial runs last year in order to get approval for 2.5 nm separation on final. This requires a documented average runway occupancy time of 50 seconds or less. YUL failed miserably. Two tests were done, one with the customers in the dark, and the second one with the customers in the know, and both results were well above the 50s mark.
YUL is just a poorly drawn up airport. It's AAR is lower because in all honesty, it has 1.5 arrival runways instead of 2. Dont even bother counting rwy 10/28. It's a taxiway more than a runway nowadays.
Thenoflyzone
24R appears to have decent exits but 24L is a bit of a dog, methinks, particularly for GA traffic. Unless they can make that first left exit, they would probably need to backtrack or exit right to later re-cross the active. Pain in the a$$ for tower... That said, do they not depart off 28 now (with the new WTM procedures, I assume?). If they're strictly east/west ops now, I can understand the lower AAR. It used to be 42-48 when I was there, likely because they could offload so many prop departures off the cross runway.