Tough Approaches

 - August 30, 2007, 10:55 AM

An easy day of flying is not hard to define. Passengers arrive on time, good weather translates into few delays and everything on the airplane works the way it was intended. Identifying a difficult day is a bit more challenging. Is it when the crew shoots a localizer approach to minimums at night with thunderstorms all around? Or is it a more complex approach in the mountains where the margin for error is defined by granite hiding just a few dots near a full-scale needle deflection? Or an ILS with a glidepath nearly double anything you might traditionally fly in the U.S.? And how does crew inexperience or arrogance play out after a long, grueling day?

Aircraft mechanical problems, air traffic concerns and weather and crew interactions form endlessly varying combinations, all of which can affect flight safety. Unfortunately, nearly 80 percent of aircraft accidents are still related to human factors. So why do smart professional pilots continue to make what look like–on the surface at least–incredibly dumb mistakes? Are there any simple solutions to prevent crews from becoming accident statistics?

Approach accidents can happen to even the most diligent pilots. For example, on what should have been a routine instrument arrival in night visual conditions to Cali, Colombia, in 1995, an American Airlines Boeing 757 crashed in the mountains, killing 159 of 163 people on board. The experienced cockpit crew lost situational awareness while trying to reprogram the FMS during an approach change. When the crew realized their predicament, they applied takeoff thrust, but it was not enough to push the Boeing above the mountain tops in time because the 757’s speed brakes were still extended.

In March 2001, a Part 135 Gulfstream III crashed short of Runway 15 at Aspen, Colo., while attempting to land after sunset and after violating the limits of the VOR circling approach. The Aspen approach is not authorized after dark. An experienced captain was manually flying the Gulfstream at the time. An anxious passenger, late for a local party, reportedly pressured the flight crew while sitting in the jump seat. A more accurate localizer DME approach has since been added at Aspen.

In the best of times, Aspen is a difficult airport and one that has caused more than its share of tense moments among cockpit crews. Although the Gulfstream crew was experienced, it had been some time since the pilots had flown the airport’s VOR approach. And why was a non-crewmember sitting in the jump seat?

While there is no one best answer to preventing approach accidents, a solid base of nuts-and-bolts flight-training experiences can go a long way as long as crews accept that education with a grain of salt.

International Pilot Services president Roger Rose likes to remind pilots that vigilance is required for any approach, not just those characterized as “tricky.” “The most difficult approach in the world is the one for which the pilot is not well prepared,” he said. These include, he added, “locations we all fly into regularly, those airports where pilots can easily grow complacent.”

Flying in to Aspen
On a visit to FlightSafety International’s DFW campus, I had an opportunity to fly a Falcon 900EX simulator through a series of approaches designed to familiarize crews before their first flight into Aspen (ASE) and London City Airport (LCY). Both approaches represent extremes in the approach-planning phase, and both airports require certification checks before pilots are allowed to fly most of the instrument approaches there.

Before the simulator session FSI instructor Scott Stoddard gave me a briefing that would allow the 900EX to fly an automated LOC DME-E approach to Aspen in VFR conditions to see what it looked like the first time. The localizer approach is the only Aspen approach that requires specific training.

My previous jet experience at Aspen has been in VFR and IFR conditions, but I was using the more complex VOR/DME approach to Runway 15. At Aspen, departures are authorized only on Runway 33 due to steep terrain to the south of the airport that can make a missed approach off Runway 15 challenging.

The Aspen VOR approach calls for an MDA of 10,200 feet msl or 2,380 feet above the ground at approximately three miles on final. This approach begins at 14,000 feet, however, 1,000 feet higher than the LOC DME. If everything comes together as it should, the runway appears in the 11 o’clock position at minimums, and a left turn
is required to intercept the centerline. In IFR conditions this can be downright dangerous considering the nearby rocks, as the Gulfstream crew learned.

The VOR approach requires no special training before arrival at Aspen, but it should since it is more difficult to fly than the localizer approach. In poor weather, catching sight of the runway at three miles nearly 2,400 feet above the ground requires a rapid descent to the 7,006-foot-long runway. With an airport elevation of nearly 8,000 msl, true airspeed is also swift at a time when it is least helpful. The Falcon 900’s slow ref speed of 116 would come in handy.

The value of the relatively new LOC DME at Aspen becomes obvious after a quick look at the approach plates, which are available only to crews who have completed an approved training course and flown the approach in the simulator using all available aircraft automation. The LOC DME approach at Aspen lines the aircraft straight down the runway centerline at minimums, reducing the workload and the MDA for some aircraft.

Stoddard positioned our Falcon at 13,000 feet in the hold at Red Table VOR in preparation for the approach. On the first approach, I observed the procedures. The weather was set so we could see the airport from more than 10 miles out. The good weather also offered me a chance to regain a new level of respect for the height and proximity of the rocks around this popular Colorado resort.

The terrain near Red Table extends just beyond 11,500 feet agl. Within a few miles of the final approach course, rocks climb to peaks of just under 12,000 agl to the east and 13,000 agl to the west.

Stoddard reminded me of one of the cardinal rules of flying into Aspen. The aircraft must be completely configured for landing early in the approach: that means gear down and flaps to landing– no exceptions–or the aircraft will never make it down in time to slow down for touchdown.

Before beginning the approach, we also briefed the missed approach, which is no small challenge at Aspen. It involves realizing that you won’t make the airport in time to begin a right turn to the northwest to intercept a back-course localizer installed to protect aircraft from the rocks as the crews initiate a climb to 14,000 feet.

Stoddard punched the buttons on the FMS and we were on our way down, with the Falcon’s autothrottles adjusting the power. It seemed pretty smooth and easy to me, but all I was doing was watching another brain make all the decisions. As we approached the final approach fix about 5.5 miles from the end of the runway, it still looked pretty good to me with the aircraft descending down to approximately 2,200 feet agl. On a clear VFR day with no wind, being slow enough early on and seeing the airport absolutely straight ahead should make landing a snap.

I turned off the autopilot and pushed the three power levers forward as I began a climbing right turn to intercept the localizer for a missed approach. The rocks look close during the missed approach because they are close.

Landing at Aspen when the weather is poor is another thing entirely. We quickly scooted back to the Red Table holding pattern, where Stoddard set the weather to minimums this time, 2,320-3, weather that would ordinarily be almost VFR cross-country limits anywhere else. The simulator allowed for breaks in the clouds during the second approach, just enough to view a few nearby peaks before we descended again into the muck.

As the Falcon approached minimums, I disconnected the autopilot and looked ahead, where I saw the lights. What makes Aspen a tough airport in IFR conditions is the natural tendency to reduce the power when you sense you’re high. In a dirty configuration, this can be a serious mistake. I began to slow the airplane gradually toward my target threshold speed of about 100. The airplane didn’t even bounce as we touched down firmly on 15.

I wanted to see the missed approach under IFR so Stoddard put the Falcon near the final approach fix again, configured for landing. At 3.9 miles from Aspen, I pushed the power up and cleaned the aircraft for the climb. I never saw the ground but did see a few rocks sticking up through the clouds in the turn.

Although the needle on the BC LOC coming alive is normally good news here, pilots need to be ready for the fact that they could be moving across the localizer signal quickly because they are close to the transmitter, especially if there is any kind of easterly breeze. Things became much calmer once we leveled at 14,000 feet.

Preparing for the London City Approach

I also tried the infamous London City (LCY) approach. Although this airport is limited to just over 70,000 operations annually, last year it handled nearly 2.5 million passengers in a mix of business airplanes and airliners. Only a few–the Falcon line, the Challenger 605, Dornier 328, some of the smaller Citations, the Embraer Legacy, the BAe 146 and the Dash 8–are certified to make the approach.

Current UK regulations prohibit “N” registered aircraft flying into London City.

This airport also requires specific training before the first live approach since the glidepath on the LCY ILS is set at 5.5 degrees. Depending upon the aircraft speed, the descent rates–especially when IFR–are eye-opening. If the airplane has a groundspeed of 130 knots, the rate works out to be 1,300 fpm. There are no mountains at London City, but the buildings sticking up near the airport are ominous.

The first VFR approach into LCY was challenging. I watched the nearby buildings whiz by at low altitude, much closer than structures were ever located at Chicago Meigs Field before it closed. As they do at Aspen, airplanes landing at London City need to be completely configured before the final approach fix. The weather minimums at LCY are considerably lower than in Colorado, varying from 360 to 460 feet agl.

While that may not sound like much of an issue at first, hurtling downward at 22 feet per second means there is little time from a first glance at the lights to beginning the landing flare.

We tried it one more time with the weather at minimums, and it was clear that it would take some time to get used to the optical illusion of being high. Stoddard talked me through the first approach, offering a few tips that made the nearly six-degree slope easier to understand, especially since I knew I would live if I botched it.

The second approach to minimums was much easier, confirming for me the value of trying these approaches out in a simulator before flying them for real in a 50,000-pound airplane.

'Tough Approaches' PDF