Landing (descent or approach)

On approach to Lagos-Murtala Muhammed Airport, the crew encountered poor weather conditions with heavy rain falls and strong winds. The copilot was in command and the airplane was too high on approach so the captain took over controls and steeped the approach. Nevertheless, the aircraft was still too high over runway 19L threshold when it encountered severe downdraft. It nosed down and struck the runway surface nose gear first. It bounced, veered off runway to the left, rolled to the apron and eventually collided with a parked Fokker F27 Friendship 200MP of the Nigerian Air Force registered NAF908. Both aircraft were destroyed and one of the pilot on board the Twin Otter was killed, all eight other occupants were injured.

Shortly after takeoff, the pilot reported he had 'a problem...an overboost situation,' and wanted to return for landing. Instrument meteorological conditions prevailed, so the pilot was cleared for the ILS runway 26 approach. A witness saw the airplane emerge from the low overcast in a wings level descent, then pitch over to a near vertical attitude and impact a shopping center sign. The left turbocharger wastegate was found in the open (low boost) position, and the right turbocharger wastegate was found in the closed (high boost) position. The right turbocharger butterfly valve was severely eroded, the pin was missing, and the valve was free to rotate on the shaft. A hole was burnt through the right engine number 1 cylinder exhaust valve. Both propellers were in the low pitch-high rpm range. Both engines and turbochargers were original equipment and had not been overhauled in 21 years. A toxicology test showed 0.564 mcg/ml of sertraline (antidepressant) in the pilot's blood. Sertraline was not approved for use while flying an aircraft.

The C-21A, a USAF designation of the Learjet 35A was assigned to the 332nd Airlift Flight at Randolph AFB, Texas. The aircraft would depart Randolph AFB as flight Kiowa 71 to Wright-Patterson AFB, Andrews AFB and then back to Randolph. The aircraft was landed at Andrews AFB at 10:57. The crew requested a full load of fuel and told Serv-Air maintenance technicians that they had been unable to transfer fuel from the wing tanks to the fuselage tank. A Serv-Air maintenance technician removed the fuel-control panel from the aircraft and replaced the fuselage-tank transfer/fill switch. The maintenance technician told the crew that replacement of the fuselage-tank switch had not corrected the problem and that he was going to try to correct the problem by replacing the fuel-control relay panel. This was a time consuming job. The crew decided to continue back to Randolph without the repairs. The fuselage fuel tank was full and they had not had trouble earlier in the day getting fuel out of the fuselage tank. The aircraft departed from Andrews AFB at 16:38. The aircraft was in cruise flight at FL390 at 17:53 when the crew began to transfer fuel from the fuselage tank to the wing tanks. The crew did not know that the right standby fuel pump was operating and was preventing fuel from being transferred from the fuselage tank to the right wing. Bearings in the right standby pump were in a deteriorated condition and the pump had required higher-than-normal electrical current for rotation. The higher-than-normal electrical current had caused progressive damage to two contacts in the fuel control relay panel and eventually had caused the contacts to bond together. This caused the pump to run continuously throughout the flight and to prevent fuel transfer from the fuselage tank to the right wing. The aircrew noticed that the left wing-tip tank had become 800 pounds [363 kilograms] heavier than the right wing-tip tank during the transfer, and they attempted to analyse the malfunction and correct the imbalance. A fuel-imbalance during-fuel-transfer malfunction however was not included in the Air Force training syllabus, nor was the procedure contained in the C-21A checklist. At 17:56, the copilot told the Atlanta Air Route Traffic Control Center (Atlanta Center) controller, "Sir, we need to revise our flight plan. We’re having a problem getting some fuel out of one of our wings. Can we get vectors to Maxwell Air Force Base? And we’re going to need to dump fuel for about five minutes." The crew at 18:00 began to dump fuel from the left wing-tip tank. However, they still had an imbalance in the wing tanks themselves of about 200 pounds (91 kilograms). At 18:03 the flight was cleared to descend from FL350. The crew then observed that fuel quantity was decreasing rapidly in the right wing tank, that the left wing tank was full and that the left wing-tip tank had begun to fill with fuel. At 18:07, the copilot told the Atlanta Center controller, "Sir, we’d like to declare an emergency at this time for a fuel problem and, ah, get to Maxwell quick as we can." They were cleared direct to Maxwell AFB and cleared to descend to 17,000 feet, and later to 11,000 feet. At 18:15, the copilot told Atlanta Center, "We need to change the airfield, to get to the closest piece of pavement we can land on." The controller said, "Kiowa 71, we got an airport at 12 o’clock and 12 miles. It’s Alexander City." The crew accepted this and began their emergency descent into Alexander City airport. At 18:16 the copilot took over control since the captain did not have the airfield in sight and the copilot did. The aircraft was northeast of the airport at 8,800 feet and was descending at 5,600 feet per minute with the wing-lift spoilers extended when the copilot told Atlanta Center that they were on a left base for the runway. The crew attempted to fly a visual traffic pattern to runway 18 but were in a poor position to complete the approach and landing. They subsequently elected to enter a left downwind leg for runway 36. As airspeed was reduced, aileron authority diminished and, because of the fuel imbalance, the aircraft became difficult to control. The copilot, flying from the right seat, did not have a good view of the runway and asked the aircraft commander for help in positioning the aircraft on downwind and in beginning the turn toward the runway. The captain wanted to get the gear down but the copilot had difficult controlling the plane already: "Don’t put anything down," the copilot said. "Nothing down, nothing down." The aircraft was at 2,030 feet when the gear-warning horn sounded. The captain said, "Gear down. Gear down." The copilot said, "No. Stand by. Stand by." "Gear down," the captain said. "Gear down, man." "No, not yet, not yet," the copilot said. The copilot then asked the aircraft commander to "push the power up a little bit for me." Power was increased and the gear was extended. The aircraft was at about 1,500 feet and was one mile southwest of the runway at 18:19 when the copilot began a left turn. Approximately halfway through the final turn and one mile due south of runway 36, the aircraft abruptly rolled out, flew through the extended runway centerline and continued in an east, northeasterly direction approximately 800 feet above the ground. The copilot had rolled out of the turn to regain lateral control of the aircraft. At this time the right engine was operating at a reduced thrust setting in an attempt to counteract the effects of the fuel imbalance. The captain, to center the ball in the slip indicator, applied pressure on the left rudder, against pressure that was being applied on the right rudder by the copilot. The captain said, "Step on the rudder. Step on the rudder." The copilot said, "Paul, no. Paul, don’t." The application of left rudder caused the aircraft to roll left rapidly. It rolled inverted entered the trees and struck the ground.

The four engine transport category airplane was carrying a load of fuel oil for distribution to the village of kivalina. The pilot reported he flew over the 3,000 feet long by 60 feet wide strip prior to landing, and noted in the center of the runway some gravel was visible through a layer of surrounding snow. He said he could not see any snow banks or deeper snow in the landing area, and available notices to airmen did not mention any snow banks or snow berms on the runway. The pilot said the airplane landed near the threshold and on the centerline, but, the left main landing gear soon encountered a snow berm and the airplane was pulled to the left. The airplane subsequently impacted other snow berms on the left side of the runway and the nose landing gear collapsed. The U.S. Government's supplement for Alaska airports, for the Kivalina Airport, states, in part: unattended. Caution: runway condition not monitored, recommend visual inspection prior to using.

After takeoff from Cuzco-Alejandro Velasco Astete, one of the tyre on the left main gear burst. The crew decided to continue to Lima when, on approach, the left main gear could not be lowered and remained stuck in its wheel well. Upon landing, the aircraft sank on its left side and slid for few dozen metre before coming to rest. All 73 occupants were evacuated safely while the aircraft was damaged beyond repair.

The crew was engaged in an humanitarian flight on behalf of Unicef. On approach to an airstrip somewhere near Likwangbala, the aircraft collided with trees and crashed. Both pilots were killed.

After making a localizer runway 08 approach, the pilot landed over halfway down the 4,422 feet wet runway. He then decided to abort the landing, added power, and when airborne, retracted the landing gear. He said he asked the right front seat (non-rated) passenger to reset the flaps (to 20°). The pilot saw trees ahead, and realized the airplane was not going to clear the obstacles, though full power was applied. Just before impact, he pulled back on the elevator control to soften the impact, rather than hitting the trees nose first. After the accident, the wing flaps were found in the retracted position. A passenger was killed and three other occupants were seriously injured.

The twin engine aircraft belly landed at Lae-Nadzab Airport. It slid down the runway for few dozen metres before coming to rest. Both occupants escaped uninjured and the aircraft was damaged beyond repair.

The single engine aircraft was dispatched at Luziânia Airport for local training purposes, carrying a crew of five consisting of one instructor and four pilot under training. Following several approaches, the aircraft was descending to the runway when the instructor reduced the engine power to simulate a failure. From a height of about 300 feet, the aircraft nosed down, lost height and crashed short of runway threshold. All five occupants were uninjured and the aircraft was written off.

The crew was completing a short flight from Santo Domingo-Las Américas Airport to Santo Domingo-Herrera Airport located in the city center. On short final, the pilot-in-command mistakenly reduced the engine power too much, causing the aircraft to lose height and to struck the runway surface with an excessive vertical speed. The aircraft landed hard, bounced and came to rest few hundred metres further. All six occupants escaped uninjured and the aircraft was damaged beyond repair.