American Eagle Flight 4184, officially operating as Simmons Airlines Flight 4184, was a scheduled domestic passenger flight from Indianapolis, Indiana to Chicago, Illinois, United States. On , 1994, the 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.
Background
Aircraft
The aircraft involved, registration was built by the French-Italian aircraft manufacturer ATR and was powered by two Pratt & Whitney Canada PW127 turboprops. 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. 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
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. Colleagues described Aguilar's flying skills in positive terms and commented on the relaxed cockpit atmosphere that he promoted. The first officer was Jeffrey Gagliano, 30. His colleagues also considered him to be a competent pilot, and he had accumulated more than 5,000 flight hours, including 3,657 hours in the ATR. There were two flight attendants, one of them was on the first day of the job.
Weather
National Weather Service reports revealed low cloud ceilings and visibility under three miles in the area. The air temperature was approximately at the accident site but at , with precipitation in the air.
The weather conditions provided by Lowell Airport, located about northwest of the accident site, indicated broken clouds at and an overcast sky at with gusty winds from the southwest at and light drizzle. However, the report observation was made about 30 minutes after the accident.
Accident
The flight was en route from Indianapolis International Airport, Indiana to O'Hare International Airport, Chicago, Illinois. Adverse weather in Chicago caused delays, prompting air traffic control to hold Flight 4184 over the nearby LUCIT intersection at . While holding, the plane encountered freezing rain, a dangerous icing condition in which supercooled droplets rapidly cause intense ice buildup. Soon after, the flight was cleared to descend to . The pilots were then ordered to enter another hold. During the descent, a sound indicating an overspeed warning caused by the extended flaps was heard in the cockpit. After the pilot took action by retracting the flaps, the pitch attitude and angle of attack of the airplane increased, followed by a sharp, uncommanded roll excursion that disengaged the autopilot. Flight recorder data showed that the aircraft rolled 77 degrees to the right, and the ailerons moved to a neutral position and the plane began rolling back toward wings level. However, another right-aileron deflection occurred as the bank angle was decreasing through 59 degrees, bringing the plane completely inverted. Throughout this roll, the data recorder showed that the first officer was sustaining nose-up elevator inputs. After the aircraft completed a full right roll and passed through a wings-level attitude, the ailerons were deflected toward the left and the roll was stopped at 144 degrees of right bank. The pilots rolled the airplane to the left, and as the bank angle decreased through 90 degrees, they applied nose-up elevator to stop the downward pitch, as the plane had reached a 73-degree nose-down attitude. By this point, the airplane was descending through . The airplane's ground-proximity warning system began to sound, followed by an expletive from the first officer and a rapid increase in nose-up elevator. A loud "crunching" sound was heard shortly before the end of the cockpit voice recording. The airplane crashed into a wet soybean field, partially inverted, in a nose-down attitude.
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 at impact. There was no fire. The distribution of wreckage, combined with data from the flight recorders, indicated that the horizontal stabilizer and outboard sections of both wings separated from the airplane prior to impact, "in close proximity to the ground." As the bodies of all on board were fragmented by the impact forces, the crash site was declared a biohazard.