American Eagle Flight 4184
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| Accident summary | |
|---|---|
| Date | October 31, 1994 |
| Type | Atmospheric icing, Loss of control |
| Site | near Roselawn, Indiana, United States |
| Passengers | 64 |
| Crew | 4 |
| Injuries | 0 |
| Fatalities | 68 (all) |
| Aircraft type | ATR 72-212 |
| Operator | Simmons Airlines |
| Tail number | N401AM |
| Flight origin | Indianapolis International Airport |
| Destination | Chicago O'Hare International Airport |
American Eagle Flight 4184,[1] was a regional airline flight that crashed after flying into known icing conditions on Halloween, October 31, 1994. Control was lost and all aboard were killed.
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[edit] History
The aircraft, N401AM, was an ATR 72-212 operated by Simmons Airlines on behalf of American Eagle, the "banner carrier regional airline branding program of AMR Corporation's regional system," prior to the formation of the fully certificated carrier named American Eagle Airlines. The flight was en route from Indianapolis International Airport, Indiana to O'Hare International Airport, Chicago, Illinois. Bad weather in Chicago caused delays, prompting air traffic control to hold Flight 4184 over the nearby LUCIT intersection at 10,000 ft (3,000 m)
While holding, the plane encountered freezing rain — a dangerous icing condition where supercooled droplets rapidly cause intense ice buildup. Soon after, they were cleared to descend to 8,000 ft (2,400 m) After this descent the pilots were ordered to make another hold. While in the holding pattern, a warning sound indicating the extended flaps was heard in the cockpit. The pilot took action by retracting the flaps. Suddenly a strange noise was heard from the whole plane, followed by an uncommanded roll excursion, which disengaged the autopilot. Flight recorder data showed that it subsequently went through at least one full roll, and the crew was unable to regain control of the rapidly descending aircraft. Then it happened again. Less than two minutes later, contact was lost as the plane crashed into a soybean field near Roselawn, Indiana, killing all 64 passengers and 4 crew on board. The disintegration of the plane indicated an extreme velocity, and data recovered from the flight data recorder verified that the plane was traveling 375 knots (695 km/h) indicated airspeed at impact[2].
Flight 4184 was the first loss of an ATR 72 aircraft, it was also the highest death toll of any aviation accident involving an ATR 72 anywhere in the world. Robert A. Clifford, a Chicago airplane accident attorney, represented 16 of the victims. As the trial was ready to begin, the defendants agreed to a record $110 million settlement and an apology in open court. [3]
[edit] Cause
The National Transportation Safety Board (NTSB) stated that the probable cause of this crash was the flight into known icing conditions, with the aircraft being operated outside its "icing certification envelope". While the ATR's deicing boots were able to remove ice along the leading edge, it rapidly re-formed behind the boots as runback ice, where it could not be removed. This separated the airflow from the wing's surface and made the aileron control inadequate or non-existent. The ATR family of aircraft has had a history of known and reported control problems in icing conditions. For that reason, the NTSB also mentioned as contributing factors the "inadequate response" on part of the manufacturer and the French Direction Générale de l'Aviation Civile (DGAC) and American Federal Aviation Administration (FAA) aviation authorities to these reports.
[edit] Aftermath
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This section needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (July 2009) |
In the years following this accident, AMR Corporation stopped using its American Eagle ATRs out of its northern hubs and moved them to its southern and Caribbean hubs in Dallas, Texas; Miami, Florida and San Juan, Puerto Rico to alleviate potential icing problems in the future. Other U.S. former ATR operators, particularly the SkyWest, Inc. subsidiary and Delta Connection operator Atlantic Southeast Airlines, operated ATR-72 aircraft in areas where icing conditions were not common.
In April, 1996 the American FAA issued 18 Airworthiness Directives (ADs), in an apparent attempt to prevent further icing accidents in ATR aircraft. They included significant revisions of pilot operating procedures in icing conditions (higher minimum speeds, non-use of the autopilot, different upset recovery procedures) as well as physical changes to the coverage area of the de-icing boots on the airfoils.
While the ATR-42 and ATR-72 aircraft are now compliant with all icing condition requirements imposed by those 18 ADs, the de-icing boots still only reach back to 12.5% of the chord. Prior to the accident, they had extended only to 5% and 7%, respectively. They still fail to deal with the findings of the Boscombe-Down tests, conducted by British regulators, which demonstrated that ice could form as far back on the wing as 23% of the chord, and on the tail at 30% of chord. Both percentages remain well beyond the limits of the extended deicing boots, installed in compliance with those FAA ADs.
Those tests limited the size of the droplets to 40 micrometres, near the maximum limit of the archaic FAA design certification rules for Transport Category aircraft (Part 25, Appendix C), still in effect at that time of the Roselawn crash. Extensive airborne testing, following that accident, revealed it is possible for airliners to encounter water droplets exceeding 200 micrometers in average diameter.[4]
It is likely that the lack of further ATR icing accidents is attributable to the changes in pilot operating procedures, as well as the moving of those aircraft to operating areas where severe icing is not a problem, rather than to the modest extension of the de-icer boots to 12.5% of the chord. [5]
Following the crash near Roselawn, longstanding problems with the ATR aircraft operating in some icing conditions were revealed by Stephen Fredrick (a whistleblower later fired by the airline).[6] American Eagle has since phased out service using ATR aircraft in cold-weather areas, replacing the aircraft with regional jets. However, ATR-72 aircraft are still used for Caribbean operations from Miami and San Juan, Puerto Rico, where ice is not an issue.
[edit] Dramatization
This crash was featured on the Discovery Channel program The New Detectives and in the theatrical production, Charlie Victor Romeo.
The crash was also featured in Season 6 of National Geographic's Air Crash Investigation in the episode "Frozen In Flight"
[edit] See also
[edit] References
- ^ "Frozen in Flight." Mayday.
- ^ ASN Aircraft accident description Aérospatiale/Aeritalia ATR-72-212 N401AM - Roselawn, IN
- ^ http://aviation.cliffordlaw.com/our-success-record/american-eagle-flight-4184
- ^ [1]
- ^ Unheeded Warning: The Inside Story of American Eagle Flight 4184
- ^ Fredrick, Stephen A. (1996). Unheeded warning: the inside story of American Eagle flight 4184. McGraw-Hill. pp. 326 pages. ISBN 0070219516, 9780070219519.
[edit] External links
- Accident description at the Aviation Safety Network
- NTSB AAR-96/01 – detailed Aircraft Accident ReportPDF (3.58 MiB), 340 pages)
- NTSB AAR-96/02 – comments of Bureau Enquète-AccidentsPDF (4.42 MiB), 341 pages)
- PlaneCrashInfo.Com entry on Flight 4184
- Tv.Com - New Detectives: Witness to Terror (Details Flight 4184 investigation)
- Site for Families and Friends of 4184
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Aviation accidents and incidents in 1994
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