Wow! Thoroughly interesting read! Thanks for taking the time to answer those questions! I do appreciate it. Again, your side of the operation has always fascinated me, especially since my Tracon visit.
Originally Posted by
Ajax
Strong winds will lower arrival rates because of extra compression on final means we need extra spacing buffer on final to account for that. Low ceilings means visual separation may not be possible, and we running bare minimum IFR separation without the ability to use visual to prevent a compression error is too risky.
Yeah, compression, I keep hearing that word. J.K. gave me a bit of an explanation on this, but I'm still not sure understand what it is and what causes it. Is it essentially caused just by strong winds making aircraft on downwind fly super fast over the ground while aircraft on final go super slow? Groundspeed difference? Is that it? Are slow groundspeeds on the approach the culprit then? And are AARs spit out by a computer at flow control, or is there any human input? Can an individual facility (i.e. ZDC, N90, LGA ATCT, etc), influence these numbers?
Originally Posted by
Ajax
Low ceilings means visual separation may not be possible, and we running bare minimum IFR separation without the ability to use visual to prevent a compression error is too risky.
Even if technically the required minimun IFR separation is the same, once the ceilings/visibility drops, and we (and the tower) lose the ability to use visual separation, we need a bigger buffer on final to avoid compression "deals".
Is this even an issue when winds aren't doing anything out of the ordinary? JFK doesn't seem to have too many problems with delays caused by ceilings, but LGA seems to go into delays even with, say a 2,000ft CIG. I could never figure out why. And when you say "use visual separation" does that refer to the tower controller visually monitoring arrivals?
Regarding your insight on visual approaches, I totally understand. You're working with some of the tightest airspace in the world, and can ill-afford having someone grossly overshoot final, or have them put themselves 8 miles behind the guy they're following before turning base. Just like how some controllers are sharper than others, the same can be said for pilots. Likewise, we tend to practice IFR procedure in VFR wx when approaching a training event, though without mucking up the operation (like slowing to approach speed 15 miles out!).
Originally Posted by
Ajax
Although I don't know the exact number, a great % of JFK traffic is heavy jets/b757's that require wake turbulence separation. EWR and LGA have less heavy jet traffic so its not unusual to see our finals tighter than JFK's.
Well, yeah, what I was getting at was why, going into JFK, we sometimes get slowed, and vectored out, and then when on the final and switched over to tower they say, "you're 7 miles behind an RJ, cleared to land." I understand if we have that kind of spacing behind a 777, but another RJ?? And not even during a staggered approach with another close parallel. Not saying that sort of thing happens often, but it never happens at LGA. If you're following another RJ at LGA, you're going to be 3 miles behind him as he's touching down. I guess this might be an instance where a controller might be over-cautious at times!
Originally Posted by
Ajax
Windshear reduces the arrival rates because the potential for go arounds is higher. Every go around becomes .....an extra arrival.
Or a diversion! But yup, that woulda been my guess. Also why super low IFR weather near mins would understandably cause a low AAR -- go-around likelihood increases. What I wasn't following was why a 1,000-1,500ft ceiling would cause a drop in AAR. I just figured that as long as you had 3sm spacing at the threshold (or whatever the applicable min spacing is given the aircraft categories), everything was good, regardless of the reported ceiling/visibility.
Originally Posted by
Ajax
The EWR downwind is super wide because departures out of EWR, TEB, MMU, and CDW need a climbout corridor to be able to get on top of the arrivals. The boundary line goes from MMU to CDW to TEB, so that is why you normally get vectored to stay on the outside, and make the wide turn. In addition, when its busy, the downwind can, and often extend all the way to SAX and is not uncommon to turn base over 4N1 (Greenwood lake airport).
Makes perfect sense. When landing 22L, can you run simultaneous visual approaches with 22R if departure demand allows? I know you can do it sparingly for 4L/4R, but don't recall it ever being done for the 22's. Also, it seems like no matter how far north the 22L downwind goes, it seems the base follows a very fine track, almost like a 150ish heading towards TEB. I'm presuming you can't have a long (20NM) final to 22L and that the final has to start over TEB? I know another airport is right there, I woulda just thought that you could have the airspace north of TEB as well, as a EWR arrival would be well above any TEB traffic.
Another silly question: I understand LGA ILS13 all but shuts down TEB, but what kind of impact (if any) does that operation (along with JFK ILS13L) have on EWR?
Thanks again so much for the info (sorry for all the whacky questions)!