Pilots Seemed Unbothered by Icing, Crash Probers Hear : Aviation: Safety board still seeking cause for commuter plane to plunge to earth, killing 68, although ice is suspected.

Questions arose Wednesday whether the cockpit crew of Flight 4184--or anyone else--was paying enough attention to the icing conditions that apparently crippled the commuter plane before it crashed into a soybean field last Halloween, killing all 68 on board.

Neither dispatchers nor air traffic controllers thought it necessary to relay forecasts and reports about the possibility of ice to Pilot Orlando Aguiar and Co-Pilot Jeffrey Gagliano before their plane took off from Indianapolis or while it was circling in a holding pattern over Roselawn, Ind., waiting to land at Chicago’s O’Hare Airport, testimony here has shown.

Although Aguiar and Gagliano were aware that ice was building up on their ATR-72 twin-turboprop, neither was concerned enough to take evasive action or to report the problem so other pilots in the area could be alerted, according to cockpit recordings recovered from the wreckage.

The cause of the crash has not been determined officially but federal investigators believe that accumulating ice distorted the shape of the aircraft’s wings and control surfaces, creating the instability that ultimately hurled it to the ground.

Jay Hoyer, manager of dispatching operations for Simmons Airlines--the company that flew Flight 4184 for American Eagle under the overall control of AMR Corp., which also runs American Airlines--testified Wednesday that while temperature and moisture readings en route were provided before takeoff, dispatchers did not tell pilots specifically that light to moderate icing had been forecast.

“They’re gonna encounter light to moderate icing almost every day,” Hoyer testified during the fourth day of National Transportation Safety Board hearings on the crash, noting that the ATR-72 has been certified to fly under such conditions.

Air traffic control officials have testified that although they had received reports from other flights about light icing in the Chicago area, they felt no need to pass those reports on to Flight 4184 because none of them conveyed a sense of urgency.

Matthew Dunne, a traffic management coordinator at Chicago’s Terminal Radar Control center, said that any decision to remove Flight 4184 from the holding pattern because of icing conditions “would be a pilot responsibility, not a controller responsibility.”

The cockpit recordings show that even after an alarm system on their plane alerted them that ice was beginning to build up, Aguiar and Gagliano remained unconcerned.

When Gagliano finally mentioned--15 minutes after the initial alarm--that “we still got ice,” Aguiar immediately changed the subject, back to the holding delay.

It was not until 2 1/2 minutes later, when the accreting ice so destabilized the plane that the autopilot kicked off and the turboprop began to spiral earthward, that the cockpit crew recognized the seriousness of the situation.

Calm and professional, they struggled mightily to control the plane, but less than 30 seconds later, they were dead.

Another American Eagle pilot, Daniel M. Rodts, testified how ice had disabled his ATR-72 as he was preparing to land at Marquette, Mich., in November, 1993.

Rodts said he regained control and landed later in Green Bay, Wis. He said that when he got out to inspect the aircraft, he found “little Monopoly houses of ice” on the tail.

Those and other incidents have raised concerns that the European-built ATR-72 and its precursor, the ATR-42, are especially susceptible to icing. But John Marwitz, a professor of meteorology at the University of Wyoming, contended that all turboprop commuter planes are equally vulnerable because they fly at altitudes where freezing rain often occurs.