American Eagle Flight 4184

American Eagle Flight 4184 was a scheduled domestic passenger flight from Indianapolis, Indiana to Chicago, Illinois, United States. On October 31, 1994, the ATR 72 performing this route flew into severe icing conditions, lost control and crashed into a field. All 68 people aboard were killed in the high-speed impact.[1]

American Eagle Flight 4184
Aerial view of the crash site
Accident
DateOctober 31, 1994
SummaryAtmospheric icing leading to loss of control[1]
SiteNear Roselawn, Indiana, U.S.
41°5′40″N 87°19′20″W
Aircraft
Aircraft typeATR 72–212
OperatorSimmons Airlines for American Eagle
Call signEAGLE FLIGHT 4181
RegistrationN401AM
Flight originIndianapolis International Airport
DestinationO'Hare International Airport
Occupants68
Passengers64
Crew4
Fatalities68
Survivors0

Background

Aircraft
An American Eagle ATR 72–212 similar to the accident aircraft

The aircraft involved, registration N401AM,[2] was built by the French-Italian aircraft manufacturer ATR and was powered by two Pratt & Whitney Canada PW127 turbo-prop engines.[3] It made its first flight on March 7, 1994, and was delivered to American Eagle on March 24, 1994. It was operated by Simmons Airlines on behalf of American Eagle.[1]:1[4][5] American Eagle was 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.

Passengers and crew
Victims' nationalities[6]
Country Passengers Crew Total
Canada 2 0 2
Colombia 3 0 3
Lesotho 1 0 1
Mexico 1 0 1
South Korea 1 0 1
Sweden 2 0 2
United Kingdom 5 0 5
United States 49[lower-alpha 1] 4 53
TOTAL 64 4 68

The captain of Flight 4184 was Orlando Aguilar, 29. He was an experienced pilot with almost 8,000 hours of flight time, including 1,548 hours in the ATR.[1]:13 Colleagues described Aguilar's flying skills in positive terms and commented on the relaxed cockpit atmosphere that he promoted.[1]:13 The first officer was Jeffrey Gagliano, 30. His colleagues likewise considered him to be a competent pilot, and he had accumulated more than 5,000 flight hours, of which 3,657 hours were in the ATR.[1]:14 The two flight attendants were 27-year-old Sandi Modaff and 23-year-old Amanda Holberg, who was working her first day as a flight attendant with American Eagle.[7]

Weather

Weather conditions in the area of Roselawn, Indiana, were recorded by National Weather Service. The summary showed a low pressure center in the area of west central Indiana, and "…cloud ceilings of less than 1,000 feet and/or visibilities of less than 3 miles, in rain,…" occurring in northern Indiana at 1600 local time. A cold front also extended from the low pressure center in a southwesterly direction. The surface temperature of the accident site was reported as 7 degrees Celsius.

The National Weather Service's analysis indicated a low pressure area whose center located in west central Indiana at 1800 local time. The temperatures in the area where Flight 4184 was, were reported near 3 degrees Celsius with moisture evident. Temperatures were near minus 4 degrees Celsius with moisture evident in northern Indiana.

The weather conditions provided by Lowell Airport, which is located about 12 nautical miles northwest of the accident site, indicated broken clouds at 1,400 ft, overcast at 3,000 ft, gusty winds from southwest at 20 knots, with light drizzle falling. However, the report observation was made about 30 minutes after the accident.[1]:17

Accident

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 enter another hold. During the descent, a 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 a sharp, uncommanded roll excursion that disengaged the autopilot. Flight recorder data showed that the aircraft subsequently went through at least one full roll, after which Aguilar and Gagliano regained control of the rapidly descending aircraft. However, another roll occurred shortly after as they engaged the autopilot again. This second occurrence was unrecoverable, and fewer than thirty seconds later, at 3:59 p.m., contact with Flight 4184 was lost as the plane crashed nose-down into a soybean field near Roselawn, Indiana, killing all 64 passengers and 4 crew on board.

The disintegration of the plane indicated extreme velocity, and data recovered from the flight data recorder showed that the plane had an indicated airspeed of 375 kn (694 km/h; 432 mph) at impact.[3] There was no fire. The bodies of all on board were fragmented by the impact forces; therefore, the crash site was declared a biohazard.[1]:73

Flight 4184 was the first hull loss, and also the deadliest aviation accident, involving an ATR 72 aircraft.[3] Sixteen years later, Aero Caribbean Flight 883 crashed into a high range of terrain, also due to icing conditions, resulting in the same number of fatalities.[8]

Probable cause

As is customary in these reports, the National Transportation Safety Board (NTSB) issued a statement of "probable cause" near the end of its report. The probable cause statement in this report was considerably longer than is typical. The NTSB found that ATR (the manufacturer of that aircraft), the French Directorate General for Civil Aviation (the French counterpart of the American FAA), and the FAA itself had each contributed to that accident, because each had failed in its duty to ensure the highest possible level of safety to the traveling public.

The unabridged NTSB "probable cause" statement reads:

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.[1]:210

BEA response and investigation

The Bureau d'Enquêtes et d'Analyses pour la Sécurité de l'Aviation Civile (BEA) made its own separate investigation and agreed with the NTSB's cause of the accident being aileron deflection leading to loss of control. However the BEA stated in its response to the NTSB's report that the aileron deflection was caused by pilot error instead of ice, citing several off-topic conversations made by the crew during the holding phase, as well as the flight crew extending the flaps to 15 degrees while at a high speed, which can create large axial loads. The BEA also stated that the air traffic controller was not adequately monitoring the flight. However the NTSB refuted the BEA’s arguments in their final report and in a separate detailed response article. In addition, there was no factual evidence to support the BEA's claims. The NTSB stated that the crews conversation took place in a non-critical moment of the flight and that the pilots were aware of the presence of ice on the wings. Therefore the NTSB concluded that the non-pertinent conversation didn’t contribute to the accident.[9]

Aftermath

In March 1995, some families of the victims discovered remains of their loved ones at the accident site, giving rise to a suspicion that cleanup efforts were not thorough. In a statement, the Newton County coroner - referring to other comments made - said he was not surprised there were remains left, given how serious the accident was.[10]

In April 1996 the FAA issued 18 Airworthiness Directives (ADs) affecting 29 turboprop aircraft which had the combination of unpowered flight controls, pneumatic deicing boots and NACA "five-digit sharp-stall" airfoils. 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.

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 Airport, Miami, Florida, and San Juan, Puerto Rico, to reduce 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.

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. Robert Boser believes the ADs still fail to deal with the findings of tests conducted by British regulators at MoD Boscombe Down, which demonstrated that ice could form as far back on the wing as 23% of the chord, and on the tail at 30% of the chord. Both percentages are well beyond the reach of the extended deicing boots installed in compliance with the 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 the accident revealed that airliners can encounter water droplets exceeding 200 micrometers in average diameter.[11] It is likely that the lack of further ATR icing accidents during the 1990s 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.

Three ATR 72's have since crashed due to icing: TransAsia Airways Flight 791 crashed on 21 December 2002, killing both pilots. Aero Caribbean Flight 883 crashed on 4 November 2010, killing all 68 people on board.[12] UTair Flight 120 crashed on 2 April 2012, due to a lack of de-icing of the aircraft prior to takeoff. 33 of the 43 people on board were killed. The crash of TransAsia Airways Flight 791 was attributed to water droplet size that was beyond Part 25, Appendix C of the FAA design certification.[13]:ii,131,156–157,178

Dramatization
  • This crash was featured in the Discovery Channel program The New Detectives in an episode titled "Witness to Terror". (The episode incorrectly gives the number of victims killed on the flight as 72.)[14]
  • The crash was featured in the theatrical production Charlie Victor Romeo.
  • The crash was featured in Season 7 of the Canadian-made documentary series Mayday, in an episode titled "Frozen in Flight".
  • The crash was briefly mentioned in an episode of Modern Marvels ("Sub Zero") on The History Channel.
gollark: Oh no.
gollark: This will have no negative consequences.
gollark: That is LITERALLY just Zig.
gollark: Sure! Note that we reserve the right to offer arbitrary sets of bees of equivalent cardinality instead.
gollark: `systemctl enable --now syncthing@[user]`, assuming you're on a systemduous distribution, which you probably are.

See also

Notes
  1. Including 1 dual South African-United States citizen.

References
  1. "In-Flight Icing Encounter and Loss of Control, Simmons Airlines, d.b.a. American Eagle Flight 4184, Avions de Transport Regiona (ATR), Model 72-212, N401AM, Roselawn, Indiana, October 31, 1994" (PDF). National Transportation Safety Board. July 9, 1996. NTSB/AAR-96/01. Retrieved February 7, 2016.
  2. "FAA Registry (N401AM)". Federal Aviation Administration.
  3. Harro, Ranter (October 31, 1994). "ASN Aircraft accident ATR-72-212 N401AM Roselawn, IN". Aviation-safety.net. Retrieved February 13, 2017.
  4. "American Eagle N401AM". airfleets.net. Airfleets aviation.
  5. "N401AM Simmons Airlines ATR 72". www.planespotters.net. Retrieved February 19, 2020.
  6. "Crew and Passengers aboard Flight 4184".
  7. McRoberts; Kendall (November 2, 1994). "From One Tragedy, 68 Stories". Chicago Tribune.
  8. Ranter, Harro. "ASN Aircraft accident ATR 72-212 CU-T1549 Guasimal, Sancti Spiritus Province". aviation-safety.net. Retrieved February 16, 2020.
  9. "In-Flight Icing Encounter, Simmons Airlines, d.b.a. American Eagle Flight 4184, Avions de Transport Regional (ATR) Model 72-212, N401AM, Roselawn, Indiana, October 31, 1994; Volume II: Response of Bureau Enquetes-Accidents to Safety Board's Draft Report" (PDF). National Transportation Safety Board via the Bureau d'Enquêtes et d'Analyses pour la Sécurité de l'Aviation Civile. May 13, 1996. NTSB/AAR-96/02. Retrieved June 27, 2019.
  10. Washburn, Gary. "Body Parts At Crash Site Anger Victims' Families". Chicago Tribune. Retrieved 2 June 2018.
  11. Boser, Robert (September 2002). "Editor's Reply to Letter to the Editor – Unheeded Warning". AirlineSafety.com.
  12. Hradecky, Simon. "Crash: Aerocaribbean AT72 near Guasimal on Nov 4th 2010, impacted ground after emergency call". The Aviation Herald. Retrieved February 15, 2020.
  13. "Inflight icing encounter and crash into the sea, TransAsia Airways Flight 791, ATR72-200, B-22708, 17 kilometers Southwest of Makung City, Phengu Islands, Taiwan, December 21, 2002" (PDF). Aviation Occurrence Report. Taipei, Taiwan: Aviation Safety Council. 1. October 25, 2003. Retrieved February 15, 2020.
  14. Witness to Terror, retrieved February 19, 2020
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