American Eagle Flight 4184

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 October 31, 1994, the ATR 72 performing this route flew into severe icing conditions, lost control and crashed into a field, killing all 68 people on board in the high-speed impact.

Flight

The flight was en route from Indianapolis International Airport, Indiana to O'Hare International Airport, Chicago, Illinois. Flight 4184 was scheduled to depart the gate in IND at 14:10 and arrive in ORD at 15:15; however, due to deteriorating weather conditions at ORD, the flight left the gate at 14:14 and was held on the ground for 42 minutes before receiving an IFR clearance to ORD. The controller did not specify to the crew the reason for the hold.

The flight crew engaged the autopilot as the airplane climbed through 1,800 feet. At 15:05:14, the captain made initial radio contact with the DANVILLE Sector (DNV) Radar Controller and reported that they were at 10,700 feet and climbing to 14,000 feet. The DNV controller issued a clearance to the crew to proceed directly to the Chicago Heights VOR. At 15:08:33, the captain of flight 4184 requested and received a clearance to continue the climb to the final en route altitude of 16,000 feet.

At 15:09:22, the pilot of a Beech Baron, N7983B, provided a pilot report (PIREP) to the DNV controller that there was "light icing" at 12,000 feet over Lafayette, and, 22 seconds later, added that the icing was "trace rime...." According to the DNV controller, because the crew of flight 4184 was on the frequency and had established radio contact, the PIREP was not repeated.

At 15:13, flight 4184 began the descent to 10,000 feet with first officer Gagliano at the controls. During the descent, the flight data recorder (FDR) recorded the activation of the Level III airframe deicing system and the propeller RPM at 86 percent.

At 15:17:24, the BOONE sector was advised by the ORD traffic controller to issue holding instructions to all inbound aircraft.

At 15:18:07, shortly after flight 4184 leveled off at 10,000 feet, the BOONE controller notified the crew that they were cleared to the LUCIT intersection and gave their holding pattern, telling them to expect further clearance (EFC) at 15:30. The captain acknowledged the transmission. About 1 minute later, the BOONE controller revised the EFC for flight 4184 to 15:45. This was followed a short time later by several radio transmissions between the captain of flight 4184 and the BOONE controller in which he received approval for 10 nmi legs in the holding pattern, a speed reduction, and confirmation of right turns while holding.

At 15:24:39, the captain of flight 4184 contacted the BOONE controller and reported, "entering the hold." The first holding pattern was flown at approximately 175 knots with the wing flaps in the retracted position. The airframe deice system was deactivated during this time, and the propeller speed was reduced to 77 percent.

At 15:33:13, the captain stated, "man this thing gets a high deck angle in these turns...we're just wallowing in the air right now." FDR data indicated that the angle-of-attack (AOA) was 5 degrees. Following this comment, the first officer moved the flaps to the 15-degree position and the aircraft returned to level flight.

At 15:38:42, the BOONE controller issued a revised EFC of 1600 to flight 4184. The captain acknowledged this transmission, and the cockpit voice recorder (CVR) recorded the flight crew continuing their discussion with the flight attendant. At 15:41:07, the CVR recorded the sound of a single tone similar to the caution alert chime, and the FDR recorded the activation of the "Level III" airframe deicing systems. About 3 seconds later, both the CVR and FDR recorded an increase in the propeller speed from 77 percent to 86 percent, as required by Level III icing conditions.

At 15:48:34, the first officer commented to the captain, "that's much nicer, flaps fifteen." About 7 seconds later, the CVR recorded one of the two pilots saying, "I'm showing some ice now." The captain remarked shortly thereafter, "I'm sure that once they let us out of the hold and forget they're down we'll get the overspeed," referencing the aural flap overspeed warning that activates if the aircraft speed exceeds 185 knots with flaps in the 15-degree position.

At 15:49:44, the captain departed the cockpit and went to the aft portion of the airplane to use the restroom. The captain returned from the restroom at 15:54:13, and upon his return asked the first officer for a status update regarding company and ATC communications. There was no verbal inquiry by the captain about the status of the icing conditions or the aircraft deice/anti-icing systems. At 15:55:42, the first officer commented, "we still got ice." This comment was not verbally acknowledged by the captain. The CVR indicated that the flightcrew had no further discussions regarding the icing conditions.

At 15:56:16, the BOONE controller contacted flight 4184 and instructed the flight crew to, "descend and maintain eight thousand [feet]." This was followed by a transmission from the BOONE controller informing the crew that "...[it] should be about ten minutes till you're cleared in." The first officer responded, "thank you." There were no further radio communications with the crew of flight 4184.

Crash

At 15:56:51, the FDR showed that the airplane began to descend from 10,000 feet, the engine power was reduced to the flight idle position, the propeller speed was 86 percent, and the autopilot remained engaged in the vertical speed and heading select modes. At 15:57:21, as the airplane was descending in a 15-degree right-wing-down attitude at 186 knots, the sound of the flap overspeed warning was recorded on the CVR. Five seconds later, the captain commented, "I knew we'd do that." As the flaps began transitioning to the zero degree position, the AOA and pitch attitude began to increase.

At 15:57:33, as the airplane was descending through 9,130 feet, the AOA increased through 5 degrees, and the ailerons began deflecting to a right-wing-down position. About half a second later, the ailerons rapidly deflected to 13.43 degrees right wing down, the autopilot disconnected, and the CVR recorded the sounds of the autopilot disconnect warning (a repetitive triple chirp that is manually silenced by the pilot). The airplane rolled rapidly to the right, and the pitch attitude and AOA began to decrease.

Within several seconds of the initial aileron and roll excursion, the AOA decreased through 3.5 degrees, the ailerons moved to a nearly neutral position, and the airplane stopped rolling at 77 degrees right wing down. The airplane then began to roll to the left toward a wings-level attitude, the elevator began moving in a nose-up direction, the AOA began increasing, and the pitch attitude stopped at approximately 15 degrees nose down.

Five seconds later, as the airplane rolled back to the left through 59 degrees right wing down (towards wings level), the AOA increased again through 5 degrees and the ailerons again deflected rapidly to a right wing down position. The captain's nose-up control column force exceeded 22 lb, and the airplane rolled rapidly to the right, at a rate in excess of 50 degrees per second, bringing the plane completely inverted.

As the airplane rolled through 120 degrees, the captain's nose-up control column force decreased below 22 pounds, and the first officer's nose-up control column force exceeded 22 pounds just after the airplane rolled through the inverted position (180 degrees). 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 captain said "alright man" and the first officer's nose-up control column force decreased below 22 pounds. The nose-up elevator and AOA then decreased rapidly, the ailerons immediately deflected to 6 degrees left wing down and then stabilized at about 1 degree right wing down, and the airplane stopped rolling at 144 degrees right wing down, a steep right bank.

Fifteen seconds after the autopilot first disconnected, the airplane began rolling left, back towards wings level. The airspeed increased through 260 knots, the pitch attitude decreased through 60 degrees nose down, acceleration fluctuated between 2.0 and 2.5 G, and altitude decreased through 6000 feet. At 15:57:51, as the roll attitude passed through 90 degrees, continuing towards wings level, the captain applied more than 22 pounds of nose-up control column force, the elevator position increased to about 3 degrees nose up, pitch attitude stopped decreasing at 73 degrees nose down, the airspeed increased through 300 knots, normal acceleration remained above 2 G, and the altitude decreased through 4,900 feet.

At 15:57:53, as the captain's nose-up control column force decreased below 22 pounds, the first officer's nose-up control column force again exceeded 22 pounds and the captain made the statement "nice and easy." At 15:57:55, the normal acceleration increased to over 3.0 G, the sound of the ground proximity warning system (GPWS) alert was recorded on the CVR, and the captain's nose-up control column force again exceeded 22 pounds. Approximately 1.7 seconds later, as the altitude decreased through 1,700 feet, the first officer made an expletive comment, the elevator position and vertical acceleration began to increase rapidly, and the CVR recorded a loud "crunching" sound. The last recorded data on the FDR occurred at an altitude of 1,682 feet (vertical speed of approximately 500 ft/s), and indicated that the airplane was at an indicated airspeed of 375 knots, a pitch attitude of 38 degrees nose down with 5 degrees of nose-up elevator, and was experiencing a vertical acceleration of 3.6 G. The CVR continued to record the loud crunching sound for an additional 0.4 seconds.

The airplane impacted a wet soybean field in Lincoln Township, Newton County, Indiana, partially inverted, in a nose down, left-wing-low attitude. The NTSB determined that the accident was not survivable because the impact forces exceeded human tolerances, and no occupiable space remained intact.

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.