Algodoo

At 15:56:51, the FDR showed that the airplane began to descend from 10,000 feet (3,048 m), 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 (214 mph; 344 km/h), 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 (2,783 m), 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 (maximum designed aileron deflection is 14 degrees in either direction from neutral), 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 pounds, 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 (299 mph; 482 km/h), the pitch attitude decreased through 60 degrees nose down, acceleration fluctuated between 2.0 and 2.5 G, and altitude decreased through 6,000 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 (345 mph; 556 km/h), normal acceleration remained above 2 G, and the altitude decreased through 4,900 feet (1,494 m).

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 (518 m), 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 (513 m) (vertical speed of approximately 500 feet per second [150 m/s]), and indicated that the airplane was at an indicated airspeed of 375 knots (432 mph; 694 km/h), 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.[1]


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.[1]: 73 

Flight 4184 was the first hull loss, and was also tied with Aero Caribbean Flight 883 as the deadliest aviation accident involving an ATR 72 aircraft, until Yeti Airlines Flight 691 crashed in 2023.