Ski Country ATC: A Proposed Solution

  • E-Mail this Article
  • View Printable Article
  • Text size:

    • A
    • A
    • A

Aircraft flying to popular Colorado ski destinations like Aspen and Eagle have been facing ever-increasing ATC delays. In this article, a Denver Center controller explains the reasons for these delays, and predicts the problem is only going to get worse. The author and some of his ZDV colleagues have proposed a solution to the FAA: creation of a new "Mountain Approach Control" facility at Grand Junction. But this probably won't happen without a congressional mandate, so if you support this idea, tell your legislators.

The Rocky Mountains of central Colorado have been greatly affected by the fast-growing popularity of skiing. It wasn't long ago that the small Colorado mountain community of Aspen came to realize this in a big way. Every year, thousands of enthusiasts flocked to their town to ski their "hills," many of them arriving by air. The amenities of Aspen were enjoyed by the general aviation community as well as some very successful mountain commuter airlines (Rocky Mountain and Aspen Airways).

Some history

At the time, the Aspen Airport was served only by a VFR tower, and had neither radar nor a navaid serving the airport for an IFR approach (except for some special airline-only approaches developed by the commuters). ATC services were provided by Denver Center, whose radar coverage was virtually non-existent below 13,000' MSL. Because of the lack of decent radar coverage, ATC had to handle IFR operations to and from Aspen using non-radar procedures-one in and one out. VFRs received vectors "down the valley." If you couldn't cancel or execute a visual approach, you went somewhere else. Not much else could be done with what we had.

Soon, traffic volume and complexity far exceeded the Center's capability to provide for the safe, efficient and orderly movement of aircraft under these difficult conditions. The FAA established a slot reservation program during ski season. Delays were routinely measured in hours, and flights were often turned away if they didn't have the appropriate reservation "slot time" or arrive within the appropriate "window" for that slot time. Extra controllers were assigned to plug in to those "ski country" sectors as a "third set of eyes," and other sectors were instructed to "miss" the Aspen sector with enroute traffic and hold Aspen arrivals at outlying intermediary fixes. Things were, very simply, getting out of hand.

Colorado Ski CountryThen came Aspen Approach. Through pressure exerted on Washington by the flying community, a congressional mandate ordered a radar approach control facility be established at Aspen. This added to the ATC system a transponder-only terminal radar site for Aspen, plus a navaid (the Red Table VOR/DME, identifier DBL) to serve the airport with an IFR approach, and a gap-filler radar site for the Center located near DBL. The terminal radar gave ATC the ability to sequence IFR traffic with 3 mile separation, and to radar separate arrivals from departures. The result was that most of the traffic problems at Aspen went away.

Deja vu all over again?

But does history repeat itself? It does, and it has. Welcome to Eagle, Colorado.

The very same problems faced at Aspen in previous years are now manifesting themselves 25 miles north at the Eagle County Regional Airport, the airport that serves the Vail and Beaver Creek ski resorts. Once small county airport with hardly any IFR operations, EGE is now the third fastest-growing commercial airport in the nation — second only to Colorado Springs and North Las Vegas, according to DOT figures — and is fast becoming the number one Colorado ski country destination and busiest mountain terminal area in the country.

In 1989, barely 300 air carrier passenger enplanements were recorded at Eagle. By 1995, there were nearly 90,000 reported. At the end of the 1996-1997 ski season, that number had doubled to nearly 180,000. The air carriers say the will begin year-round service to Eagle as early as 1998, and expect traffic volume to double again within the next two years to well over 300,000 passenger enplanements. Keep in mind that the great majority of this traffic takes place within the six-month period from November to April. While these figures deal strictly with air carrier operations, general aviation traffic at Eagle is experiencing similar growth.

You can now fly non-stop to Eagle from such places as ORD, DTW, ATL, DFW, MSP, IAH, LAX, EWR, LGA, IAD, MIA, SLC and of course DEN. Where once you might have spotted a single DHC-7 commuter or two on the ramp at Eagle, you can now see a vast assortment of B757's, B727's, B737's, BA46's and others. The airlines are spending big money to develop facilities at Eagle. American Airlines for example, is pumping millions of dollars into the airport to handle their B757 operations. They have built their own terminal and developed their own FMS approach and departure procedures. Both Northwest (B757's) and Delta (B727's) have followed suit. Even Air Wisconsin (BA46's), United (B737's) and Continental (B757's) are getting into the act. They have recognized a business opportunity and are capitalizing on it.


And how is ATC handling it? Well, basically, we're not! We're reliving yesteryear at Aspen. It's basically a non-radar airport, because even with the DBL gap-filler radar site, we can't see below 9,000' to 9,500' MSL within a 5 to 10 mile radius of the airport. It has a VFR tower operated by a contractor (Midwest ATC Services, Inc.), and that tower is only there because the air carriers forced the issue. In fact, scheduled closing time at Eagle tower is 7:00 pm local, but the controllers often stay on duty until 10:00 or 11:00 pm until the last air carrier flight has arrived, with their overtime pay picked up by the airlines.

Eagle LOC DME-C ApproachEagle does have navaids and IFR approach procedures. But because of the non-radar environment, IFR at EGE is basically a one-in, one-out affair. To make matters worse, take a look at the LOC DME-C approach: it's 33 NM from the initial approach fix (Kremmling VOR, identifier RLG) to the airport, and it usually takes an aircraft 10 to 12 minutes to execute the published approach. If (heaven forbid) the aircraft misses the approach, it's another 23 NM to the missed approach fix (JESIE intersection) and 20 NM more back to RLG. Adding it all up, if you fly the approach, go missed, and want to try it again, you will have flown 76 NM and literally "tied up" the airspace for nearly a half hour! Talk about being handcuffed! Expeditious handling under these conditions is a whopping 4 aircraft an hour, and that's if we're lucky.

Fortunately, the weather at Eagle is VFR much of the time. Although the air carriers never cancel IFR and seldom accept a visual approach, many general aviation operators do, and that helps boost the acceptance rate. But when weather conditions drop to MVFR or IFR or when pilots who are unfamiliar with the area prefer (understandably) not to cancel, the system gets easily backlogged and severely overloaded. At Denver Center, the controllers feel like they're trying to pour a gallon of water into a quart jar without being able to see the jar and trying not to spill a drop.

Flow control

The FAA has a plan to deal with this problem. Unfortunately, it comes as the expense of our "customers" and adversely affects general aviation most of all.

Every year between about Thanksgiving and mid-April, Denver Center's Traffic Management Unit (a.k.a "flow control") implements a "ski country" program. What this basically does is schedule a certain number of arrivals into a particular airport during each one-hour period, based on a specific acceptance rate determined ahead of time based on factors such as forecast weather, equipment outages, etc. The idea, of course, is to hold ski-country-bound IFR departures on the ground as necessary so that they don't overwhelm our capacity to handle arrivals. Sounds reasonable, but it's got several problems.

For one thing, all that this program does is to control departure times. Any delays that occur enroute (vectors for traffic, deviations around weather, equipment problems, etc.) renders the ETA useless. Apply Murphy's Law and you'll see that instead of the steady stream of arrivals that we're supposed to get, the aircraft tend to arrive in bunches.

For another, the TMU's method of "slot" scheduling discriminates severely against general aviation. This occurs because the TMU automatically pencils in scheduled air carrier operations into its hourly slots first, then makes any remaining slots available to general aviation. So, for example, it's IFR at Eagle and TMU sets the acceptance rate at six aircraft per hour (about normal), and if there are six air carrier arrivals scheduled to arrive during a particular hour, there would be no slots left for G.A. operators. During some hours, only 1 or 2 air carriers are scheduled to arrive at EGE; during other hours, as many as 5 are scheduled. Furthermore, if EGE weather goes down low enough that the TMU thinks there's a reasonable chance of missed approaches, it lowers the acceptance rate to just two aircraft per hour (remember, it takes a half-hour to shoot the approach and miss). Under such circumstances, the chance of a G.A. operator getting into EGE are between slim and none. Feel like a second-class citizen yet?

When the weather is forecast to be VFR, no slot program is implemented. While this might seem to be good news, that's not necessarily so. Even in VFR weather, the IFR acceptance rate doesn't increase to much over six aircraft an hour because of the non-radar one-in/one-out environment. So with an unlimited flow of IFR aircraft headed for RLG, you can expect delay vectors and/or holding at outlying fixes while we juggle the arrivals to establish the necessary miles-in-trail. If that doesn't sound good, you can always cancel IFR...but you better have your head on a swivel. Last year, an air carrier did take evasive action in response to a TCAS alert to avoid traffic during the occurrence of a very complex ATC operational error that resulted in loss of standard separation between aircraft in the sector. I highly recommend never departing for Eagle with anything less than your maximum available fuel load and, if it's IFR, a precisely blueprinted alternate plan. We're still dealing with a quart jar here.

To make matters worse...

Current Sector PlanWhen the new Denver International Airport opened, Denver Center realigned the vertical and lateral boundaries of the sectors surrounding the Denver terminal area. The western boundary of the sector handling westbound departures off DEN (Sector 6) was extended approximately 35 NM west to reach out nearly 100 NM west of DEN, and now encompasses Eagle Airport and one each of the major Aspen arrival and departure gate streams. The once easily-controlled sector with a single basic mission, overnight became an unmanageable nightmare with a trio of terminal difficulties.

It was all these factors—ineffective flow controls, inferior equipment and an ominously supersaturated sector—that prompted me to file an Unsatisfactory Condition Report in January of 1997. The FAA has still not responded to this filing, having given themselves (to date) six extensions to the required time period for providing such a response. They have now given themselves until January 1, 1998—nearly a full year from the original filing date and two months into ski season—to think about it.

But this is not to say that the solution is simply to move the boundary back. The sector that gave up the Eagle airport to sector 6 was similarly overburdened. That sector (Sector 11), prior to the resectorization, provided approach control services to not only Eagle, but Hayden, Steamboat Springs, Grand Junction and other mountain airports, all of them experiencing fast-paced growth. The sector was also responsible for the other three arrival and two departure gate streams serving Aspen.

Geographically, sector 11 covered nearly the entire state of Colorado west of the Continental Divide. An effective sector "scan" was a near-impossible task for one controller. To make matters worse, the need for multiple communications sites to cover the huge mountainous area meant that aircraft frequently "stepped on" clearances and readbacks. It was simply too much airspace for one person to handle. Something clearly had to be done.

The resectorization did help sector 11 (by shrinking it), but it hurt sector 6 (by expanding it). Moving the sector boundary back is not the answer. The problem is the huge increase in traffic at these airports (especially Eagle), and it's not going to be solved by robbing Peter to pay Paul.

Is there a solution?

Proposed Sector PlanWe think so. We are a group of controllers and members of the National Air Traffic Controllers Association that are petitioning the FAA and Congress for the development of a new "Mountain Approach Control Facility" to be located in Grand Junction, Colo. This facility would take on the responsibility of providing approach control services to the Aspen, Eagle, Rifle and Grand Junction airports collectively. It would combine the current Aspen and Grand Junction approach control facilities and take all the airspace in between, including Eagle to the north. It would be staffed by the personnel currently assigned to Aspen Approach and Grand Junction Tower, and relieve Denver TRACON of the burden entirely.

[The present ATC situation at Grand Junction is also quite controversial, and a controller at Denver Approach has filed another Unsatisfactory Condition Report with the FAA over the fact that approach control service at GJT is provided using non-ARTS (i.e., non-approach certified) radar via a 300-mile-long chain of sixteen microwave links and other communications relays over the Continental Divide to Denver TRACON. But that's another story.]

Many of the logistics involved in the creation of Mountain Approach Control have already been addressed by NATCA. The Walker Field Airport Authority (Grand Junction) has offered to make the portion of the air traffic control tower building not currently being leased by the FAA available to house the new facility. Hardware and software vendors have been contacted, and we have received estimates of "off the shelf" products available today for system integration and modernization. Personnel issues have been outlined (moves, staffing, training, etc.). And all the while, our cost projections have remained in check. In fact, what we have proposed would be considerably less expensive that what the GAO estimates will be the cost of the modernization projects currently budgeted by the FAA (such as STARS). We believe that our proposal would return the level of ATC service in the Rocky Mountain area to what the users expect from it, while the FAA's current plans do not address the issues in our judgment.

How you can help

In order for this to happen, we could use a little help. We realize that if we simply wait for the FAA bureaucracy to adopt our proposal for Mountain Approach Control, we'll probably reach retirement age before anything happens. It took a tremendous lobbying effort by users and a congressional mandate to get the facility built at Aspen, and we think it will take another to get a Mountain Approach Control facility built in Grand Junction. In the short term, we need the FAA to commit the resources to install one more radar site at Eagle, and we need to prevent the FAA from carrying out it's current plan to contract out the operation of Grand Junction tower in early to mid-1998.

So in September, a group of NATCA representatives traveled to Washington D.C. to meet with representatives of Colorado's congressional and senatorial delegations to present the Mountain Approach Control proposal. That got the ball rolling. Through the months of October and November, several meetings have been called with legislators and users alike to discuss the proposal. We are currently embarking on a letter-writing campaign to convey support of the proposal to Colorado's Legislators. We have an open invitation to them, or anyone, to come to Denver Center and see the operation, and fully expect some visits this winter.

Our Mountain Approach Control proposal (a 74-page document) goes into considerable detail on how the proposed facility would work and what resources it would need. To make it more accessible to interested parties, we have posted the proposal on the World Wide Web at We invite you to look it over. If you'd like more information, feel free to drop me a line at, or visit our "Contact" page on the web for a detailed list of government, legislative and local contacts. If you like what you see and would like to let Colorado's Legislators know, visit our "Write Colo.'s Senate" and "Write Colo.'s Congress" page for sample letters we're using in our letter writing campaign. Copy and mail them to our representatives if you're so inclined. We surely would appreciate your support.

We think our proposal resolves many of the issues of safety and service in Colorado's ski country that exist today and will get worse tomorrow. We also realize how difficult it is to justify projects such as this, and ultimately pry the funds from very tight congressional budgetary hands. Facilities all across the nation need help. But our basis is sound and our direction clear. We are committed to preserving over the skies of Western Colorado the quality of safety and service of the caliber that is expected of the finest air traffic system in the world. You should demand nothing less.