Crash Danger Looms While Experts Debate Rules For Icy Dc-9 Jets

On a cold and icy day, a departing DC-9 jet roars down the runway and lifts 100 feet. Without warning, one of its wings dips toward the ground. The pilots fight to keep the stalling plane in the air, but within seconds they lose control and the plane crashes.

This horrifying scenario has happened not once, not twice, but again and again - for a total of five times in 23 years. Thirty people have died in those DC-9 crashes - including two pilots killed in a crash in Cleveland in February - while 33 others have been seriously injured.

The reason for the accidents is simple: Ice or frost, with a thickness usually not more than 30-grit sandpaper - twice the size of salt grains - had settled on the wings. All planes are susceptible to stalling because of ice on their wings, but the evidence indicates that the design of one model of the popular DC-9 - the series 10, the earliest version - has even less margin for error.

Unlike most commercial jets, the DC-9-10 does not have slats, essentially retractable auxiliary wings mounted on the wing's front edge that give extra lift at takeoff. Later DC-9 models have slats, which appear to give an extra edge of protection. Crash records show that no other jet has had as many icing accidents per commercial flight as the DC-9-10.

But despite the common thread in the accidents, a Newsday investigation has found, virtually nothing has been done to require new procedures for flying the DC-9-10 jet in icy weather, or even to make sure that pilots are consistently told about the plane's proclivity to stall with trace amounts of ice on the wings. In fact, pilots originally trained to fly the series 30 jet - which has slats and has never had an icing crash - have twice ended up crashing the series 10.

A review of dozens of accident reports, letters between government agencies, memos from the manufacturer to airlines, and depositions and other documents from court cases disclosed that the icing incidents with the DC-9-10 were allowed to fester over the years with almost no action by government officials. By the third crash in 1985, it was clear a trend was emerging, but little was accomplished because of bureaucratic inertia, lack of follow-through, and assurances from the manufacturer that it was dealing with the issue.

The story of the DC-9's icing accidents shows how air-safety problems can slip through the cracks, adding to the death toll. Regulators, the manufacturer and the airline operators missed warning signs, in part because the early accidents weren't fatal. Investigations focused on pilot error, not the plane. Recommendations to deal with the icing problem were ignored or forgotten. In the end, the system designed to prevent future accidents failed.

Five accidents for the same reason "is disturbing to say the least," said one government official who asked not to be identified. "Two or three is enough to be concerned about the subject."

The two-engine, DC-9-10 jet, though more than 20 years old, is still in use. Almost 100 are registered in the United States. Northwest Airlines operates nearly three dozen of them, while Trans World Airlines, Midwest Express and several cargo operators also fly them.

No one really debates whether crews should attempt to take off with ice on the wings. The rules strictly forbid it. If a plane crashes and ice has been found on the wing, the tendency has been to blame the crew for failing to get rid of it. But the track record of the DC-9-10 has raised questions about whether it should be singled out for special attention.

Among the problems uncovered:

-- The National Transportation Safety Board, the independent federal agency charged with investigating accidents, may have mismanaged the DC-9 problem. After the third accident in 1985, the safety board staff developed a draft copy of safety recommendations for the DC-9-10. But the draft was never formally presented to the safety board for approval. Then, after the fourth accident in 1987, the safety board made a mild recommendation that airlines develop new procedures for detecting ice on the wings of DC-9-10 jets. The Federal Aviation Administration rejected the proposal in early 1989, but the safety board never responded to the rejection letter, failing to follow its own procedures. The agency remained unaware of the lapse until Newsday reviewed the correspondence and brought it to the attention of senior officials. "I'm a little concerned that we may have dropped the ball on it," said William Laynor, the board's deputy director of aviation safety.

-- The FAA, responsible for maintaining air safety, appears to have inconsistently reacted to icing problems with jets. Over the years, the FAA has maintained that no new rules for the DC-9-10 are needed because the federal air regulations specifically prohibit pilots from taking off with ice, snow or frost on the wings of any plane. But, despite that sweeping stance, in the early 1980s the FAA worked with Boeing to develop new takeoff procedures in icy weather for the Boeing 737 jet after the deadly 1982 crash of an Air Florida 737. Boeing says incidents in which the plane pitched up because of wing ice have ceased since it implemented these procedures. The FAA acknowledges the "actions taken for the two different model airplanes are not the same," but says it consistently emphasized that no ice should be on the wings.

-- Douglas Aircraft Co., the jet's manufacturer, has mostly dealt with the problems raised by the icing accidents through non-binding memos, which simply warn airlines to follow federal rules and remove all ice from the wings. Even with five accidents, officials point out, the DC-9-10 jet has had an accident rate of one crash every 1.7 million commercial flights. After the latest accident, it sent another memo out - this time to the chief executives of airlines - and, just last month, held a seminar for airline-operation officials on the problem. Douglas officials reject the need for government rules or new procedures that would make the problem clear to all crews who fly these jets.

But with about half the jets in the United States owned by leasing companies, it is sometimes difficult to keep track of who is operating the jets, aviation officials say. The lesson may also get lost over time.

Northwest started flying DC-9s when it purchased Republic Airlines in 1986. Pilots recall that the Republic flight manuals spelled out the differences between the DC-9-10 and the other models, especially warnings about ice, but that section was later removed by Northwest. Now, "there's nothing specific in the manuals or in training" about the DC-9-10, Northwest spokesman Bob Gibbons said.

The problem first appeared late in 1968, when a DC-9 crew flying for Ozark Airlines dismissed ice about one-sixteenth of an inch thick as insignificant.

The Ozark DC-9-15 jet took off, but just as the captain began to retract the landing gear, the plane stalled and rolled abruptedly to the right. The plane crashed 1,000 feet beyond the runway, seriously injuring the pilots and a flight attendant.

As the crew of that Ozark flight learned, the leading edge of the aluminum wing is supposed to be polished smooth, but ice and frost are rough. (One DC-9-10 flying in Africa even stalled during flight because a swarm of insects stuck to the wing.)

Since frost or ice don't form in the same pattern on both wings, one wing tends to stall first, causing the roll that first alerts the crew to the impending crisis. And because of the design of the DC-9-10, a stall from wing ice can start before the stall warning system kicks in.

No aircraft officially is engineered to fly with snow on the wings, but experts say the design of an aircraft makes a difference in how it handles. Slats, which are on virtually all new jet wings, may help to avoid icing accidents because they provide extra lift. They may also be less accident prone because they're usually hidden under the wing and are only extended moments before takeoff, before ice can form. Only one commercial jet with slats, the Air Florida Boeing 737, has ever been involved in a major icing accident on takeoff.

Besides the five DC-9-10 accidents, there have been three commercial crashes and one training accident involving the unslatted Fokker F28, a Dutch jet. Both the F28 and the DC-9 have twin engines mounted on the tail, but experts say the F28 wing design tends to give more lift at takeoff. The four-engine DC-8 also has no slats, and has been involved in two accidents attributed by some to icing. Yet other jets without slats, such as the four-engine Boeing 707 and the twin-engine British Aerospace BAe 1-11, have had no accidents.

"It's not that this is a defective wing," said Gregory Wells, associate counsel of a Canadian commission investigating the 1989 icing crash of a F28 in Dryden, Ontario, that killed 24. "It is just that a wing without slats is very sensitive."

Nearly nine years after the Ozark crash, on Nov. 27, 1978, a TWA crew crashed its DC-9-10 jet at Newark International Airport, where conditions were similar to those in Sioux City. No one was seriously hurt, and the crash attracted virtually no attention. As one former TWA executive recalled, with an edge of pride: "We kept that so damn quiet you never even knew it happened."

By the time the next DC-9-10 accident occurred, in 1985, there had been a spectacular icing accident, this time only minutes from the safety board's Washington, D.C., headquarters: the 1982 Air Florida crash that killed 78 people, including four on the ground. More than 20 safety recommendations resulted, including new takeoff procedures for the 737 jet.

It was in this environment that the safety board staff pondered the lessons of an Airborne cargo jet crash in Philadelphia Feb. 5, 1985. The DC-9-15 had landed about 11 p.m., and spent 35 minutes loading cargo in freezing drizzle. The pilots agreed there was no ice: The captain looked at the wing from the cockpit and the co-pilot checked it from the cargo door. Both pilots rubbed their hands along the fuselage and felt no ice, just wetness. But the plane crashed anyway, a virtual repetition of the Ozark and TWA accidents, seriously injuring both pilots.

Airborne submitted two reports to the safety board suggesting something was seriously wrong with the plane, in particular the possibility that the roughness on the wing from frost could also disturb the flow of air entering the engines mounted just behind the wing. This combination of the stalling wing and the stalling engine might have conspired to create the accident, the report said.

"The industry needs to know the facts of this case and a full and complete analysis of the three referenced accidents is clearly called for," Airborne declared.

Meanwhile, a safety board staff member, apparently mindful that the recommendations for the Boeing 737 had proven successful, proposed similar solutions. According to a draft copy of the recommendation, the staff suggested that all DC-9-10 flight manuals be amended to emphasize the hazards of trace amounts of precipitation on the wing and the critical need to de-ice the plane when the temperature is below 32 degrees. Moreover, concerned that airlines may be lifting the nose too quickly on takeoff, the draft recommended emphasizing careful takeoff procedures in freezing weather.

But none of these steps was taken. The staff report gathered dust and was never formally submitted for approval. On its own, Airborne overhauled its flight manual to include a boxed warning to its crews on the differences between the DC-9-10 and other DC-9 models and Midwest Express adopted the Airborne procedures, Other airlines largely remained in the dark about Airborne's steps.

In the meantime, on Nov. 7, 1985, Douglas sent a memo to all DC-9 operators titled, "Takeoff With Undetected Ice on the Lifting Surfaces." The memo suggested no new One problem with so-called all-operators memos is that there is no assurance that airlines are heeding the manufacturer's concerns, airline executives say. The memos don't have the force of law, and they can be so obtusely written that the real meaning is lost.

By the fourth crash, people began to die. On Nov. 15, 1987, an inexperienced Continental Airlines co-pilot, paired with a new captain, tried to take off from Denver in a snowstorm with a DC-9-14 that had been de-iced 27 minutes earlier. The co-pilot, who trained in a DC-9-30 simulator and had a history of poor performance, pulled the nose up too quickly when the plane began to stall. Both pilots, a flight attendant and 25 passengers died in the inferno.

Ultimately, the safety board placed much of the blame for the accident on the crew and the airline, while clearing Douglas. Regarding the DC-9-10, the safety board only recommended that manuals include ways to detect ice on a wing's upper surface.

The FAA within weeks swiftly rejected the proposal, saying it "does not believe that there is anything unique about the DC-9-10 series aircraft (including the absence of slats) that would warrant special ice detection procedures."