American Eagle Flight 4184
Encyclopedia
American Eagle
Flight 4184 was an American Eagle ATR 72
that crashed after flying into unknown icing conditions
on October 31, 1994. Control was lost and all aboard were killed.
, 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 10000 ft (3,048 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 8000 ft (2,438.4 m). After this descent the pilots were ordered to make another hold. While in the holding pattern, a warning sound indicating an overspeed warning due to the extended flaps was heard in the cockpit. After the pilot took action by retracting the flaps, a strange noise was heard on the cockpit voice recorder, followed by an uncommanded roll excursion which disengaged the autopilot
. Flight recorder
data showed that the ATR subsequently went through at least one full roll with the crew able to regain control of the rapidly descending aircraft. However, another roll occurred shortly thereafter. Fewer than thirty seconds later, contact was lost as the plane crashed into a soybean
field near Roselawn, Indiana
(coordinates: 41.0944; -87.3222), 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 (734.9 km/h) indicated airspeed at impact.
Flight 4184 was the first loss of an ATR 72 aircraft and 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.
later fired by the airline).
The National Transportation Safety Board
(NTSB) issued its usual statement of "Probable Cause" near the end of the report. However, that statement was considerably longer than is the norm for most other NTSB accident reports. The statement clearly blames ATR (the manufacturer of that aircraft), the French DGAC (the French equivalent of the American FAA), and the FAA itself, as contributing to that accident, because they all failed in their duty to ensure the highest possible level of safety to the traveling public. The unabridged NTSB Probable Cause statement:
; 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 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.
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.
program The New Detectives
and in the theatrical production, Charlie Victor Romeo
.
The crash was also featured in Season 6 of Discovery Channel's Mayday
/ National Geographic's Air Crash Investigation in the episode "Frozen In Flight"
American Eagle Airlines
American Eagle Airlines is a brand name used by American Eagle Airlines, Inc. , based in Fort Worth, Texas, and Executive Airlines based in San Juan, Puerto Rico, in the operation of passenger air service as regional affiliates of American Airlines. All three airlines are wholly owned subsidiaries...
Flight 4184 was an American Eagle ATR 72
ATR 72
The ATR 72 is a twin-engine turboprop short-haul regional airliner built by the French-Italian aircraft manufacturer ATR. ATR and Airbus are both built in Toulouse, and share resources and technology...
that crashed after flying into unknown icing conditions
Icing conditions
In aviation, icing conditions are those atmospheric conditions that can lead to the formation of water ice on the surfaces of an aircraft, or within the engine as carburetor icing. Inlet icing is another engine-related danger, often occurring in jet aircraft. These icing phenomena do not...
on October 31, 1994. Control was lost and all aboard were killed.
History
The aircraftAircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...
, N401AM, was an ATR 72-212
ATR 72
The ATR 72 is a twin-engine turboprop short-haul regional airliner built by the French-Italian aircraft manufacturer ATR. ATR and Airbus are both built in Toulouse, and share resources and technology...
operated by Simmons Airlines
Simmons Airlines
Simmons Airlines is the predecessor to American Eagle Airlines based in the United States. Its headquarters were originally near Marquette, Michigan, at the Marquette County Airport in Negaunee, and were eventually moved to the Near North Side of Chicago, Illinois.- History :Simmons Airlines, Inc....
on behalf of American Eagle, the banner carrier regional airline
Regional airline
Regional airlines are airlines that operate regional aircraft to provide passenger air service to communities without sufficient demand to attract mainline service...
branding program of AMR Corporation's regional system, prior to the formation of the fully certificated
Operating certificate
Operating certificate is a category of license issued by a government agency allowing an individual or company to provide a controlled type of service. These certificates are generally issued for a limited time period...
carrier named American Eagle Airlines. The flight was en route from Indianapolis International Airport
Indianapolis International Airport
Indianapolis International Airport is a public airport located seven miles southwest of the central business district of Indianapolis, a city in Marion County, Indiana, United States. It is owned and operated by the Indianapolis Airport Authority...
, Indiana
Indiana
Indiana is a US state, admitted to the United States as the 19th on December 11, 1816. It is located in the Midwestern United States and Great Lakes Region. With 6,483,802 residents, the state is ranked 15th in population and 16th in population density. Indiana is ranked 38th in land area and is...
to O'Hare International Airport
O'Hare International Airport
Chicago O'Hare International Airport , also known as O'Hare Airport, O'Hare Field, Chicago Airport, Chicago International Airport, or simply O'Hare, is a major airport located in the northwestern-most corner of Chicago, Illinois, United States, northwest of the Chicago Loop...
, Chicago, Illinois. Bad weather in Chicago caused delays, prompting air traffic control
Air traffic control
Air traffic control is a service provided by ground-based controllers who direct aircraft on the ground and in the air. The primary purpose of ATC systems worldwide is to separate aircraft to prevent collisions, to organize and expedite the flow of traffic, and to provide information and other...
to hold Flight 4184 over the nearby LUCIT intersection at 10000 ft (3,048 m)
While holding, the plane encountered freezing rain
Freezing rain
Freezing rain is the name given to rain that falls when surface temperatures are below freezing. The raindrops become supercooled while passing through a sub-freezing layer of air, many hundred feet , just above the surface, and then freeze upon impact with any object they encounter. The resulting...
— a dangerous icing condition where supercooled droplets rapidly cause intense ice buildup. Soon after, they were cleared to descend to 8000 ft (2,438.4 m). After this descent the pilots were ordered to make another hold. While in the holding pattern, a warning sound indicating an overspeed warning due to the extended flaps was heard in the cockpit. After the pilot took action by retracting the flaps, a strange noise was heard on the cockpit voice recorder, followed by an uncommanded roll excursion which disengaged the autopilot
Autopilot
An autopilot is a mechanical, electrical, or hydraulic system used to guide a vehicle without assistance from a human being. An autopilot can refer specifically to aircraft, self-steering gear for boats, or auto guidance of space craft and missiles...
. Flight recorder
Flight recorder
A flight recorder is an electronic recording device placed in an aircraft for the purpose of facilitating the investigation of an aircraft accident or incident. For this reason, flight recorders are required to be capable of surviving the conditions likely to be encountered in a severe aircraft...
data showed that the ATR subsequently went through at least one full roll with the crew able to regain control of the rapidly descending aircraft. However, another roll occurred shortly thereafter. Fewer than thirty seconds later, contact was lost as the plane crashed into a soybean
Soybean
The soybean or soya bean is a species of legume native to East Asia, widely grown for its edible bean which has numerous uses...
field near Roselawn, Indiana
Roselawn, Indiana
Roselawn is a census-designated place in Newton and Jasper counties in the U.S. state of Indiana. The population was 4,131 at the 2010 census....
(coordinates: 41.0944; -87.3222), 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
Flight data recorder
A flight data recorder is an electronic device employed to record any instructions sent to any electronic systems on an aircraft. It is a device used to record specific aircraft performance parameters...
verified that the plane was traveling 375 knots (734.9 km/h) indicated airspeed at impact.
Flight 4184 was the first loss of an ATR 72 aircraft and 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.
Probable Cause
Following the crash near Roselawn, longstanding problems with the ATR aircraft operating in some icing conditions were revealed by Stephen Fredrick (a whistleblowerWhistleblower
A whistleblower is a person who tells the public or someone in authority about alleged dishonest or illegal activities occurring in a government department, a public or private organization, or a company...
later fired by the airline).
The National Transportation Safety Board
National Transportation Safety Board
The National Transportation Safety Board is an independent U.S. government investigative agency responsible for civil transportation accident investigation. In this role, the NTSB investigates and reports on aviation accidents and incidents, certain types of highway crashes, ship and marine...
(NTSB) issued its usual statement of "Probable Cause" near the end of the report. However, that statement was considerably longer than is the norm for most other NTSB accident reports. The statement clearly blames ATR (the manufacturer of that aircraft), the French DGAC (the French equivalent of the American FAA), and the FAA itself, as contributing to that accident, because they all failed in their duty to ensure the highest possible level of safety to the traveling public. The unabridged NTSB Probable Cause statement:
-
- 3.2 Probable Cause
-
- The National Transportation Safety Board determines that the probable causes of this accident were the loss of control, attributed to a sudden and unexpected aileron hinge moment reversal that occurred after a ridge of ice accreted beyond the deice boots because: 1) ATR failed to completely disclose to operators, and incorporate in the ATR 72 airplane flight manual, flightcrew operating manual and flightcrew training programs, adequate information concerning previously known effects of freezing precipitation on the stability and control characteristics, autopilot and related operational procedures when the ATR 72 was operated in such conditions; 2) the French Directorate General for Civil Aviation’s (DGAC’s) inadequate oversight of the ATR 42 and 72, and its failure to take the necessary corrective action to ensure continued airworthiness in icing conditions; and 3) the DGAC’s failure to provide the FAA with timely airworthiness information developed from previous ATR incidents and accidents in icing conditions, as specified under the Bilateral Airworthiness Agreement and Annex 8 of the International Civil Aviation Organization.
-
- Contributing to the accident were: 1) the Federal Aviation Administration’s (FAA’s) failure to ensure that aircraft icing certification requirements, operational requirements for flight into icing conditions, and FAA published aircraft icing information adequately accounted for the hazards that can result from flight in freezing rain and other icing conditions not specified in 14 Code of Federal Regulations (CFR) Part 25, Appendix C; and 2) the FAA’s inadequate oversight of the ATR 42 and 72 to ensure continued airworthiness in icing conditions.
Aftermath
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 at Dallas-Fort Worth International AirportDallas-Fort Worth International Airport
Dallas/Fort Worth International Airport is located between the cities of Dallas and Fort Worth, Texas, and is the busiest airport in the U.S. state of Texas...
; Miami, Florida
Miami International Airport
Miami International Airport , also known as MIA and historically Wilcox Field, is the primary airport serving the South Florida area...
and San Juan, Puerto Rico
Luis Muñoz Marín International Airport
Luis Muñoz Marín International Airport is a joint civil-military public airport located in Carolina, Puerto Rico, three miles southeast of San Juan. Over 4 million passengers board a plane at the airport per year according to FAA reports . It is owned and managed by the Puerto Rico Ports...
to alleviate potential icing problems in the future. Other U.S. former ATR operators, particularly the SkyWest, Inc.
SkyWest, Inc.
SkyWest, Inc. is the parent company of SkyWest Airlines , Atlantic Southeast Airlines, and ExpressJet Airlines. It is headquartered in St. George, Utah, United States.-History:...
subsidiary and Delta Connection
Delta Connection
Delta Connection is the name under which a number of individually owned regional airlines and one wholly owned regional carrier operate short and medium haul routes in association with Delta Air Lines Inc...
operator Atlantic Southeast Airlines
Atlantic Southeast Airlines
Atlantic Southeast Airlines is an American airline based in the A-Tech Center in College Park, Georgia, flying to 144 destinations as a Delta Connection carrier and, as of February 2010, commenced service as a United Express carrier. It is a wholly owned subsidiary of SkyWest, Inc. ASA operates...
, 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 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.
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.
Dramatization
This crash was featured on the Discovery ChannelDiscovery Channel
Discovery Channel is an American satellite and cable specialty channel , founded by John Hendricks and distributed by Discovery Communications. It is a publicly traded company run by CEO David Zaslav...
program The New Detectives
The New Detectives
The New Detectives: Case Studies in Forensic Science is a documentary true crime television show that aired two to three different cases in forensic science per episode. Episode reruns currently air on the Discovery Channel, TLC and the Investigation Discovery network...
and in the theatrical production, Charlie Victor Romeo
Charlie Victor Romeo
Charlie Victor Romeo is a 1999 play whose script consists of almost-verbatim transcripts from six real-life aviation accidents and incidents. "Charlie Victor Romeo," or CVR, derived from the NATO phonetic alphabet, is aviation lingo for cockpit voice recorder...
.
The crash was also featured in Season 6 of Discovery Channel's Mayday
Mayday (TV series)
Mayday, also known as Air Crash Investigation in the United Kingdom, Australia and Asia and Air Emergency and Air Disasters in the United States, is a Canadian documentary television programme produced by Cineflix investigating air crashes, near-crashes and other disasters...
/ National Geographic's Air Crash Investigation in the episode "Frozen In Flight"
See also
- Scandinavian Airlines Flight 751Scandinavian Airlines Flight 751Scandinavian Airlines Flight 751 was a regularly scheduled Scandinavian Airlines flight from Stockholm, Sweden to Copenhagen, Denmark and Warsaw, Poland that crashed on 27 December 1991. The McDonnell Douglas MD-81 was piloted by Danish captain Stefan G. Rasmussen and Swedish first officer Ulf...
- Aero Caribbean Flight 883Aero Caribbean Flight 883Aero Caribbean Flight 883 was an international scheduled passenger flight from Port-au-Prince, Haiti, to Havana, Cuba, via Santiago de Cuba. On 2010, the Aero Caribbean ATR-72-212 operating the route crashed in the central Cuban province of Sancti Spíritus, killing all 61 passengers and 7 crew...
- Ice protection system