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In article "Warren Jones" > > "Steven P. McNicoll" > news:sqcuojqrt9139@corp.supernews.com... > > > > news:8nrinp$jl1$1@nnrp1.deja.com... > > > > > > The report says that 18% is due to en-route delays, so quite obviously > > > theyre not dismissing en-route as being a factor. Newps already > > > mentioned the runway capacity issues, so I wont repeat it. > > > > > > > But what do they consider to be an en-route delay? > > > > > > > > > > For example, adding more runway may seem like the silver bullet in some > > > cases, but having spoken with some people here that work on ETMS Im not > > > so sure. A familiar analogy I am reminded of is the modem. Give em a > > > faster modem, theyll find a larger file to transfer. Give the airlines > > > more runway and like the snake that grows to the size of the box you put > > > it in, theyll find more planes to schedule in. > > > > > > > Agreed, but what would enroute capacity enhancements do? Sure, better > > surveillance and altimetry could reduce the current 5 miles/2000 feet > > minimum separation to, lets say, 3 miles/1000 feet. But if 20 miles in > > trail regardless of altitude is still required due to the lack of runway > > capacity, what has been accomplished? > > > > > > Hear, Hear. That about sums it up. I would agree that there are a bunch of > enroute bottlenecks, the VXV area (known as the "BURNE" sector ZTL Sec 39) > being case in point for my area of specialization. I believe that WAAS, > ADS-B et al or another form of sat surveillance would be a great tool for > tightening up enroute traffic (although wed need new comm equipment also- > like data link- so that we could handle more traffic in a sector at a time). > Any Center controller east of the Mississippi can tell you horror stories > about enroute volume. At ZTL, every Thursday and Friday youd swear were > the *busiest*, most complicated traffic mess youd ever seen, until the next > week, when the new mess supplants the old mess in your memory. "Good Lord, > yall should have seen it yesterday. ZNY shut the door on ZDC and ZDC > slammed it on us! Spin em! I cant take another airplane! First it was > the 50 MIT for NY terminal arrivals, then we held the Washington traffic > right over VXV and CLT, then the wx blew up at Hartsfield and ATL shut us > off... God what a mess... you missed a great night Bro! Black Thursday, > were callin it. We had seven patterns going at once! Central Flow > rerouted all the Texas traffic over Knoxville to Toledo, ZID had us feeding > CVG traffic 30 MIT with 10 miles and 20 reported at CVG, SDF went down to a > 1 runway op, this @sshole pilot and I got into it right on the freq about > the MCO to LAX flow reroute via Omaha, and Shamika called in sick again > (runnin from traffic, she needs to find a desk job at the RO) and they > wouldnt call in any overtime... [sigh] man, is this a GREAT job or what! > It was GLORIOUS!!!" > > But the *crux* of the matter is the capacity of the destination airport to > handle the scheduled inbounds. With the exception of wx impacting a > departure gate at a hub airport causing a ground-hold, it is destination > airport-capacity and the ability of Center to feed aircraft to TRACON over > the arrival fix (any in the NAS, pick one-itll do) that will continue to > govern enroute delays. To me this amounts to more than just pouring > concrete too but that is a good euphemism for the problem. At Center, I can > work departures just about as fast as TRACON can ship them, using 5-5-3 > minima. Problem is I cant ship the same volume back to TRACON. The AAR is > based on a lot of factors, but mainly wx and runway capacity. Thus, the AAR > is a flexible denominator that starts with the peak, best case scenario and > rapidly goes down hill (like a good NATCA all-night drinking party). > > The airlines schedule more than the AAR for peak periods because they say > thats when Mom and Dad and the kids want to fly to Boise. They are in a > cutthroat competetion with each other and schedules are a major battlefield. > There is the daily departure crush (which can be solved by more runways and > terminal space etc), but it is nothing like the arrival crush. When the > Majors schedule 130 inbounds to a filed like ATL, which can handle 120 > like-types, (no heavies, landing one a minute on parallel runways), then we > have an instant delay of ten for the push. Those ten inbound to ATL will > hold in the air outside the 40 DME because in ATL, we like to keep as much > pressure on the field as possible. No wasted gaps etc. We hold every day > into ATL regardless of wx because the major airlines that serve ATL have > decided it is better business to accept the hold in the air rather than on > the ground. We also issue ATL-bound ground-stops for the same ZTL-internal > airports every day when we go to the hold, same time, every day. One of the > most amazing things you can watch is the Center guy feeding the TRACON. > "Give me 5 miles between these 3, go to 10 after Delta 123, after Citrus 202 > hold everyone else for a 10 minute EFC so we can favor the Rome fix for a > few minutes." > > An airport like CVG (or ORD for that matter) has the same daily > overscheduling problem at the known peak times. However, ATC doesnt hold > every day because the ARTCC airpace that surrounds the TRACON is not > sectorized for holding. Instead, they get the aircraft spaced out enroute, > issue some last minute adjustments, and pump them into the TRACON. For > places like CVG we Center types run around like chickens with our heads cut > off getting 20, 30 or 40 MIT on VMC days to keep the last ZID ARTCC sector > before the arrival gate from holding inbounds. This is also known as > metering. We do this regardless of the wx at CVG. We used to call these > "static restrictions" but anything static is not PC in todays Flow Control > environment, so we now call them "Historically Validated Restrictions". > Same deal. It means that the Majors that fly into CVG (and ORD) are treated > to a high-altitude airshow hundreds of miles south of their destinations as > ARTCC slows em and turns em and forces them out of the fuel efficient high > flight levels to cross imaginary sector boundries at less efficient > altitudes, lining them up in 20, 30 or more miles in trail, all to keep them > from holding in the air just short of their destination. You can imagine > what the airline professionals think about enroute ATC, but its all based > on the capacity of their destination. Throw in a mix of heavies and turbo > props and the real AAR at a destination hub goes lower. Even if we tighten > up enroute technology to allow reduced vertical and lateral separation > between enroute aircraft, basic air safety dictates that mixed speeds and > mixed wake turbulence tolerances are going to impact how tight we run the > final. Throw in wx and IMC at the destination and AARs plummet. > > Like someone once said on TV, arrivals are like a bunch of marbles in a > funnel. Think of the funnel as the NAS and the funnel neck as the > destination hub airport. The controllers job is to keep the marbles from > hitting anywhere and to referee as they make their way down into the neck at > different speeds, some bigger than others, some faster etc. The problem is > that all of these marbles eventually have pass through the neck to reach > their destination. The airlines keep adding more and more marbles into the > same small funnel. At some point, youll have more marbles *in* the funnel > than can pass *through* the funnel neck. If we make the bowl bigger and > reduce the amount of space we have to have in the funnel between marbles > (ie- enroute ATC improvements), we can have more marbles in the funnel at > the same time. And we will still have the same problem: only a finite amount > of marbles can pass through the funnel regardless of how many marbles we can > pour into it. The key to the whole problem isnt the size of the funnel, > but the size of the neck at the bottom of the funnel. We have to expand the > capacity of this neck to see improvement. It amounts to more concrete, and > the means to take advantage of that concrete. Either that, or regulate the > amount of marbles we put into the bowl, and that aint gonna happen. > > Chip, > ZTL Intense ;) I just got an e-mail and will be attending a short ATC orientation training course, which will include site visits for Logan ATC and Manchester enroute center. Afterwards, I may actually understand more of what you said above :) Regards, Jon -- "L5 is cancelled." - Tarver in rec.aviation.ifr Sent via Deja.com http://www.deja.com/ Before you buy. |
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