A Winter Wakeup Call for Business Aviation

 - November 6, 2006, 4:03 AM

Seeing Susan Saint James on the Today show early last month remembering the life of her 14-year-old son, Teddy Ebersol–one of three people who died in the crash of a Challenger 601 at Montrose, Colo., on November 28–brought into stark focus the pain of business aviation’s recent dark spell. This mother’s grief and strength just five days after her loss were moving, and made only more tragic when viewed against the circumstances of the accident as currently told by the NTSB.

The Board investigators had recently announced that they were told the pilots of the Challenger had declined to deice the airplane before takeoff. Observers of business aviation safety had been quick to ascribe similarities between this accident and the one that killed all aboard a Challenger 604 attempting to take off with frost-contaminated wings at Birmingham, England, on Jan. 4, 2002. That comparison may or may not prove to be correct, and AIN’s goal here is not to prejudge the NTSB’s final findings on blame but to stimulate awareness among pilots on winter hazards. Official verdicts will likely not emerge for many months, and the Montrose accident, and the susceptibility of some aircraft to even small amounts of ice contamination, has to be discussed now, during the icing season.

Emotions had been running high on NBAA’s Air Mail forum since before the Montrose accident, with one pilot declaring he had no sympathy for the crew that died in the Houston Gulfstream III accident because they had busted minimums and paid a high but predictable price. The gist of the fusillade of responses was that no one has the right to be so insensitive as to declare pilots guilty before the official verdict is handed down.

Judgment Calls

But the unpalatable similarity in all these recent fatal business-jet accidents does appear to be lack of sound judgment by pilots, and to dismiss discussion of the role of judgment in accidents is to exercise a form of denial that aviation learned long ago benefits no one. Whether or not the lack of a good glycol dousing turns out to be identified officially as the root cause, it is simply common sense in icing season for pilots to wise up and think that perhaps there, indeed, go I but for the grace of God and my continued diligence. No one is condoning the publicly posted “They screwed up and got what they deserved” verdict that riled NBAA’s Air Mailers. But to contemplate and discuss that possible failing by the Montrose pilots is not insensitive. Quite the contrary, it is incumbent upon anyone who sits in the cockpit of a business jet to do so–particularly one with so-called “hard” wings (more on which shortly).

What makes the Montrose accident doubly sad to those who see close parallels with the Birmingham accident is that the British Air Accidents Investigation Branch (AAIB) had only recently released its official verdict on the Birmingham accident, and the findings were covered in this magazine at least. British investigators placed blame primarily on the pilots for failing to have the Challenger’s wings deiced before attempting to take off, and also noted that their performance might have been impaired by the combined effects of a non-prescription drug, jet lag and fatigue. The result of the pilots’ failure to defrost the wings was a “reduction in the wing stall angle of attack, due to the surface roughness associated with frost contamination, to below that at which the stall protection system was effective.”

Further, the AAIB listed as possible contributory factors FAA guidance material suggesting that polished wing frost is acceptable; melting of the frost on the right wing by the APU exhaust gas (it was the airplane’s left wing that dropped and contacted the runway shoulder after rotation); and inadequate warnings on the drug packaging.

Shortly after the Montrose accident, the FAA said it is reviewing the British AAIB’s recommendation that it change its icing regulations, which currently permit takeoff as long as the ice on an airplane’s wings is polished rather than rough.

Both Challengers that crashed with ice as a known or suspected cause were conducting charters, prompting some to question just how the decision is made whether to deice or not. If a deicing costs, say, $2,500, that is an expense the charter provider can ill afford to absorb, and the cost is usually added to the customer’s bill. Are pilots exercising command judgment and authority and ordering deicing if they see the slightest need? Or is it possible that a pilot, seeing only marginal ice contamination on the airframe, might subconsciously fertilize a lead passenger’s impatience to depart right away? Part of the nobility of aircraft captaincy stems from instinctual resistance against such potentially risky pressures. Maybe it would be wise to rethink the term “on demand” in relation to airplane charter.

The risks of ice contamination on airplanes with so-called hard wings lacking leading-edge slats are well known, and it’s worth reviewing a couple of case histories where the ice won and airplanes were lost. One involved a USAir Fokker F28-4000 that crashed on takeoff at New York La Guardia Airport on March 22, 1992, killing 27 people and injuring another 21.

The Dutch-built twinjet had been deiced twice before leaving the gate that wintry Sunday night. However, in the 35 minutes that elapsed between the second deicing and the attempted takeoff, wintry precip had accumulated on the wings. The NTSB noted that the 35 minutes exceeded the 11-minute safe holdover time for Type 1 deicing fluid. It also did not help that, during the takeoff run, the first officer called VR 11 knots early and the captain rotated about five knots short of the correct VR speed. After lifting off, the airplane stalled and came to rest partially inverted, its cockpit and forward fuselage submerged in Flushing Bay.

The Board noted that at the time of the accident USAir did not require a specific exterior inspection of F28s for ice contamination during periods of freezing precip, despite an accident history that “shows that nonslatted turbojet transport-category airplanes have been involved in a disproportionate number of takeoff accidents in which undetected upper wing ice contamination has been cited as the probable cause or sole contributing factor.”

35 Minutes of Exposure

The Board blamed the accident on the failure of the airline industry and the FAA to provide flight crews with procedures, requirements and criteria compatible with departure delays in conditions conducive to airframe icing, and on the decision by the flight crew to take off without positive assurance that the airplane’s wings were free of ice accumulation after 35 minutes of exposure to precipitation following deicing. “The ice contamination on the wings resulted in an aerodynamic stall and loss of control after liftoff,” wrote the Board.

The USAir crew was conducting its pretakeoff checks as the F28 taxied out to La Guardia’s Runway 13, having already been deiced twice after sitting in snowfall described by the first officer (PNF) as “not heavy, no large flakes.” He recalled that the windshield heat was on low, snow was sliding off the airplane and its nose had a watery layer as far as his arm could reach out of the window. They selected engine anti-ice for both Speys, and the captain announced that the flaps would remain up during taxi and that for takeoff they would use USAir’s contaminated-runway procedures, which included use of 18 degrees of flap. The first officer said that the captain then announced they would use a reduced V1 of 110 knots.

The FO further said he used the windshield wipers “a couple of times” and that he used the wing inspection light to examine the right wing “maybe 10 times, but at least three.” He said he saw no contamination on the wing or on the black strip on the leading edge during any of the several times he checked before the start of the takeoff. The crew of a Northwest 757 immediately behind the F28 subsequently confirmed this by noting that the wings had appeared to be clear.

The F28 did not climb far before it began rolling, scraping its left wingtip on the runway and then taking a straight-line course off the left side of the runway until it came to rest on the edge of Flushing Bay. The captain died in the accident, but the first officer lived to tell the tale.

The accident history to which the Board referred included the loss, just over a year earlier (in the very early morning hours of Feb. 17, 1991), of a Ryan International Airlines Douglas DC-9-15 attempting to take off from Cleveland Hopkins Airport (CLE) in Ohio. The airplane was carrying mail for the U.S. Postal Service, and landed at Cleveland on that Saturday night after flying from Buffalo, N.Y. During the unloading of mail from Buffalo and the loading of mail for the next and final port of call (Indianapolis), the two pilots stayed in the cockpit the entire time the airplane was on the ground at Cleveland. During those 35 minutes, snow fell, reported as dry and blowing. Neither Ryan Flight 590 nor any other flight that took off from Cleveland Hopkins during the evening or early morning hours of Feb. 16-17 requested or received deicing service. Ten minutes after the accident, the temperature and dew point at CLE were 23 degrees F and 20 degrees F, respectively.

Shortly after midnight the crew received taxi clearance, and at 0018:17 the DC-9 was cleared to take off on Runway 23L. As some witnesses described it, the airplane lifted off from the runway and at between 50 and 100 feet it rolled to the right, followed by a severe roll to the left beyond 90 degrees before crashing.

Roll Sequence

The tower controller saw the roll sequence differently. After the airplane had rotated and climbed to about 100 feet, he saw it make a quick bank to the left, followed by a quick bank to the right. He then saw a fireball come out of the rear of the airplane, after which it banked more steeply to the right, past 90 degrees, then pitched up farther and rolled beyond 90 degrees to an inverted attitude before hitting the ground.

Revealing the rapid progression of what seemed like a normal takeoff to disaster, the cockpit voice recorder (CVR) taped the captain making the following callouts during the takeoff sequence: “Vee one” at 0018:44; “rotate” at 0018:45; “vee two” at 0018:48; “plus ten” at 0018:49; and “positive rate” at 0018:50. The captain then warned the first officer three times in quick succession to “watch out,” beginning at 0018:51 and ending about one second later. At 0018:52, immediately after the last call to “watch out,” the CVR recorded sounds similar to engine compressor surges and, at 0018:53, the sounds of a stick shaker. The sound of the first impact occurred at 0018:57 as the airplane’s left wing struck the grass on the right side of the runway.

It’s sobering to think these two accidents happened 13 and 12 years ago, and yet a hard-winged jet came to grief in Birmingham, England, two years ago, felled by winter weather. Now Montrose, simply because of the suspicions it arouses in icing season and regardless of the future official verdict, should prompt all pilots to reset their mental alarm that even modest amounts of winter contamination on wings can spell disaster.