THE PILOTS of American Eagle Flight 4182 which crashed on 31 October, 1994, were aware that their ATR 72 was icing up, but did not believe that the problem was serious enough to cause them to lose control of the aircraft.
A transcript of the aircraft's cockpit-voice recorder (CVR) was released at the US National Transportation Safety Board's (NTSB) public hearing into the fatal crash at Roselawn, Indiana.
The CVR shows that the crew, n a holding pattern for Chicago's O'Hare International, turned on wing "boot" de-icing devices when ice started building up on the wing. It also shows they were caught by surprise and unable to control the aircraft when it flipped over and plunged 9,000ft (2,750m) to the ground in about 30s, killing all 68 on board. Air- traffic controllers testified that the crew did not ask for special handling because of icing.
A probable cause determination for the crash is not due to be identified for several months, but the US Federal Aviation Administration has developed new flight-safety and training procedures for the ATR 42 and ATR 72 as a result of its probe into the fatal accident.
Flight tests at Edwards AFB, California, left no doubt that the ATR 42 and ATR 72 comply with icing-certification regulations, but abnormal icing conditions not covered by any certification requirement could cause loss of aircraft control.
The long-term solution is a larger de-icing boot, which will be compulsory once tested. In-flight tests of the enhanced de-icing boot system began on 4 March at Edwards AFB, California. The flight evaluation is subjecting the system to icing conditions more than five times as severe as required by FAA icing standards.
Source: Flight International
