Oshkosh

**This report was modified on April 2, 2020. Please see the public docket for this accident to view the original report.**
After the airplane touched down on the 4,422-ft-long runway, the airline transport pilot applied the brakes to decelerate; however, he did not think that the brakes were operating. He continued "pumping the brakes" and considered conducting a go-around; however, there was insufficient remaining runway to do so. The airplane subsequently continued off the end of the runway, impacted a berm, and came to rest upright, which resulted in substantial damage to the right wing. During postaccident examination of the airplane, brake pressure was obtained on both sets of brake pedals when they were depressed, and there was no bleed down or reduction in pedal firmness when the brakes were pumped several times. Examination revealed no evidence off any preimpact anomalies with the brake system that would have precluded normal operation. In addition, the pilot indicated that he was not aware of and was not trained on the use of the ALL INTERRUPT button, which is listed as a step in the Emergency Procedures section of the airplane flight manual and is used to disable the anti-skid brake system functions and restore normal braking when the brakes are ineffective; thus, the pilot did not follow proper checklist procedures. According to data downloaded from the airplane's diagnostic storage unit (DSU), the airplane touched down 1,280 ft beyond the runway threshold, which resulted in 2,408 ft of runway remaining (the runway had a displaced threshold of 734 ft) and that it traveled 2,600 ft before coming to rest about 200 ft past the runway. The airplane's touchdown speed was about 91 knots. Comparing DSU data from previous downloaded flights revealed that the airplane's calculated deceleration rate during the accident landing was indicative of braking performance as well as or better than the previous landings. Estimated landing distance calculations revealed that the airplane required about 3,063 ft when crossing the threshold at 50 ft above ground level. The target touchdown speed was 76 knots. However, the airplane touched down with only 2,408 ft of remaining runway faster than the target touchdown speed, which resulted in the runway overrun.

The pilot was landing at a large fly-in/airshow and following the airshow arrival procedures that were in use. While descending on the downwind leg for runway 27, the pilot was cleared by a controller to turn right onto the base leg abeam the runway numbers and to land on the green dot (located about 2,500 ft from the runway's displaced threshold). About the time the pilot turned onto the base leg, he observed an airplane taxi onto the runway and start its takeoff roll. The controller instructed the pilot to continue the approach and land on the orange dot (located about 1,000 ft from the runway's displaced threshold) instead of the green dot. The pilot reported that he considered performing a go-around but decided to continue the approach. As the pilot reduced power, the airplane entered a stall and impacted the runway in a right-wing-low, nose-down attitude. Witnesses estimated that the bank angle before impact was greater than 60 degrees. A postaccident examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation.
Analysis of a video recording of the accident showed that the airplane was about 180 ft above ground level (agl) when the turn onto the base leg began, and it descended to about 140 ft agl during the turn. The airplane's total inertial speed (the calculated vector sums of the airplane's ground speeds and vertical speeds) decreased from 98 knots (kts) to 80 kts during the turn. During the last 8 seconds of flight, the speed decreased below 70 kts, and the airplane descended from about 130 ft agl to ground impact. The wings-level stall speed of the airplane at maximum gross weight with landing gear and flaps down was 59 kts. In the same configuration at 60 degrees of bank, the stall speed was 86 kts and would have been higher at a bank angle greater than 60 degrees. Reduced runway separation standards for airplanes were in effect due to the airshow. When the accident airplane reached the runway threshold, the minimum distance required by the standards between the arriving accident airplane and the departing airplane was 1,500 ft. The video analysis indicated that it was likely that a minimum of 1,500 ft of separation was maintained during the accident sequence. Although the pilot was familiar with the procedures for flying into the airshow, the departing airplane
and the modified landing clearance during a period of typically high workload likely interfered with the pilot's ability to adequately monitor his airspeed and altitude. As a result, the airplane entered an accelerated stall when the pilot turned the airplane at a steep bank angle and a low airspeed in an attempt to make the landing spot, which resulted in the airplane exceeding its critical angle of attack. At such a low altitude, recovery from the stall was not possible. Although the airshow arrival procedures stated that pilots have the option to go around if necessary, and the pilot considered going around, he instead continued the unstable landing approach and lost control of the airplane.

The accident occurred during the Experimental Aircraft Association’s Airventure 2010 fly-in convention. Because of the high density of aircraft operations during the fly-in, the Federal Aviation Administration implemented special air traffic control procedures to accommodate traffic demand and maximize runway capacity. Arriving aircraft were issued landing instructions and clearances by a tower controller using a specified tower radio frequency. Departing aircraft were handled by another team of controllers operating on a separate radio frequency that was associated with a mobile operations unit located near the runway. Air traffic control data indicated that the accident airplane established contact with the tower controller and entered a left traffic pattern for runway 18R. As the accident airplane was turning from downwind to base leg, the controller handling departures cleared a Piper Cub for an immediate takeoff and angled departure (a procedure used by slower aircraft to clear the runway immediately after liftoff by turning across the runway edge). The accident pilot was not monitoring the departure frequency, and, therefore, he did not hear the radio transmissions indicating that the departing Piper Cub was going to offset to the left of the runway after liftoff. The accident pilot reported that, while on base leg, he became concerned that his descent path to the runway would conflict with the Piper Cub that was on takeoff roll. He stated that he overshot the runway centerline during his turn from base to final, and, when he completed the turn, his airplane was offset to the right of the runway. The pilot stated that, at this point, he decided not to land because of a perceived conflict with the departing Piper Cub that was ahead and to the left of his position. The pilot reported that he initiated a go-around, increasing engine power slightly, but not to takeoff power, as he looked for additional traffic to avoid. He estimated that he advanced the throttle levers "probably a third of the way to the stop," and, as he looked for traffic, the stall warning stick-shaker and stick-pusher systems activated almost simultaneously as the right wing stalled. The airplane subsequently collided with terrain in a nose down, right wing low attitude. A postaccident review of available air traffic control communications, amateur video of the accident sequence, controller and witness statements, and position data recovered from the accident airplane indicated that the Piper Cub was already airborne, had turned left, and was clear of runway 18R when the accident airplane turned from base to final. The postaccident examination did not reveal any preimpact mechanical malfunctions or failures that would have precluded normal operation of the airplane. The airplane flight manual states that, in the event of a go-around, the pilot should first advance engine thrust to takeoff power and then establish Vref (reference landing approach speed). The pilot's decision not to select takeoff power during the go-around directly contributed to the development of the aerodynamic stall at a low altitude.

At 1400 cst, modified Douglas DC-3C/BT-67R, TZ-389, and Beech A36, N3657A, began formation flight to get DC-3 flying time and for the 2nd occupant of the A36 to get aerial photos of the DC-3. A witness saw the airplanes at 500 feet to 700 feet agl, "flying close together heading north." He said "the big plane (DC-3) was flying straight and level. The little plane (A36) was just to the west of the big plane. The little plane then hit the big plane near the middle." After impact, pieces of acft were seen falling. Another witness saw the DC-3 heading north and the A36 circling it above and below. On its last pass, the A36 circled behind the DC-3, then crossed over the top and hitting the top of the DC-3. About 5 seconds after impact, the DC-3 gently rolled/turned westbound (apparently descending and gaining airspeed); the left wing then came off, followed by the right wing about 2 seconds later. Parts of the A36 empennage were found 3590 to 4,910 feet from the main wreckage. There was evidence that during impact, the DC-3 elevator and rudder controls were severed. No preimpact anomalies were found. At 1445 cst, an AIRMET had been issued, forecasting light to moderate turbulence below 8,000 feet msl. Toxicology tests of the DC-3 copilot's blood showed 0.127 mcg/ml amitriptyline (a prescription antidepressant with sedative side effects), 0.039 mcg/ml nortriptyline (metabolite of amitriptyline), and an undetermined amount of ephedrine and phenylpropanolamine (over-the-counter medications used in cold preparations, diet aids and stimulants).

The pilot was flying the twin engine airplane in the traffic pattern for a fly-by event at an air show. Two fly-by circuits had been completed, and the airplane was on the third downwind leg at an estimated altitude of 600 to 800 feet agl when the right engine lost power. The main landing gear had been previously extended, and the pilot elected not to retract the landing gear in anticipation of landing on the runway. The pilot reported that he performed emergency procedures by pushing the throttles forward and attempting to restart the right engine. The right engine did not restart, and the airplane collided with terrain short of the runway. The pilot did not claim to have feathered the inoperative right engine's propellers. Postaccident inspection of the right engine revealed no evidence of preimpact anomaly. The right engine's magnetos and carburetor were damaged and not functionally tested. The propeller of the right engine was found in an unfeathered, fine pitch position. All five occupants were injured, four seriously.

The airplane was on its way from Green Bay to Oshkosh, flying at an altitude of 2,500 feet in relative good weather conditions when it collided with an Air Wisconsin De Havilland DHC-6 Twin Otter 200 registered N4043B. En route from Sheboygan to Appleton with six passengers and two pilots on board, the Twin Otter was descending to Appleton Airport. At the time of the accident, both airplanes were flying under VFR in an uncontrolled airspace. Following the collision, both aircraft crashed into Lake Winnebago, some five miles southeast of Appleton Airport. Debris were found floating on water, both airplanes were totally destroyed and all 13 occupants were killed.