Scheduled Revenue Flight

Lauda Air Flight 004 (NG004) was a scheduled passenger flight from Hong Kong to Vienna, Austria with an en route stop in Bangkok, Thailand. The flight departed Bangkok at 1602 hours on May 26, 1991 for the final flight sector to Vienna Austria. All pre-flight, ground, and flight operations appear routine until five minutes and forty five seconds after the cockpit voice recorder (CVR) recorded the sounds of engine power being advanced for takeoff. At this point a discussion ensued between the crew members regarding an event later identified as a crew alert associated with a thrust reverser isolation valve. The crew discussed this alert for some four and one half minutes. The Quick Reference Handbook (QRH) was consulted to determine appropriate crew actions in response to the alert. No actions were required, and none were identified as being taken. Ten minutes and twenty seconds into the flight the co-pilot advised the pilot-in-command of the need for rudder trim to the left. The pilot-in-command acknowledged the co-pilot's statement. Fifteen minutes and one second into the flight, the co-pilot stated "ah reverser's deployed." Sounds similar to airframe shuddering were then heard on the CVR. Twenty nine seconds later the CVR recording ended with multiple sounds thought to be structural breakup. Flight conditions were recovered from non-volatile memory in the left engine electronic engine control (EEC). At the suspected point of reverser deployment, the EEC readout indicated that the airplane was at an approximate altitude of 24,700 feet, a speed of Mach 0.78, and developing climb power. The airplane crashed in mountainous jungle terrain at 14 degrees 44 minutes North latitude and 99 degrees 27 minutes East longitude at approximately 1617 hours. Night time visual meteorological conditions prevailed. All 223 occupants were killed.

Following an uneventful flight from Sukhumi, the crew initiate the approach to Leningrad-Pulkovo Airport in heavy rain falls. At a distance of 7 km on approach, at an altitude of 400 meters and at a speed of 287 km/h, flaps were deployed to an angle of 45°. Fifteen seconds laters, at a distance of 5,700 meters, the crew was cleared to land and continued the approach when the aircraft passed below the glide. With a rate of descent of 7 meters per second and at a speed of 250 km/h, the aircraft struck the ground 13 meters short of runway threshold in a 1° nose down attitude and with a positive acceleration of 4,5 g. The aircraft broke in three parts and came to rest 80 meters to the left of the runway. 13 passengers were killed, 38 other occupants were injured and 130 escaped uninjured.

The aircraft departed Ternate Airport at 0153LT on the second leg of a flight from Ambon to Manado. While descending by night to Manado-Sam Ratulangi Airport, the crew encountered limited visibility due to poor weather conditions when the aircraft struck the slope of Mt Klabat located 15 km southeast of runway 36 threshold. The aircraft was destroyed upon impact and all 13 occupants were killed. It was raining at the time of the accident and the mountain was shrouded in clouds.

The pilot was supposed to proceed under VFR mode to the west but as weather conditions deteriorated with low clouds, he decided to continue to the south. While flying between two mountains, the single engine aircraft encountered atmospheric turbulences and the pilot elected to return when the aircraft lost height and struck trees. Upon impact, both wings were torn off and the aircraft crashed in a wooded area. All 11 occupants were injured, four of them seriously.

While descending to Aweil Airport, the twin engine aircraft went shot down by a surface-to-air missile and crashed in an open field located about 25 km from Aweil. All eight occupants were killed.

On final approach to Nuku Hiva Airport runway 06, at an altitude of about 2,000 feet, the left engine failed. The crew decided to perform an approach to runway 24 when on final, the captain ditched the aircraft few dozen meters offshore. The impact was relatively violent and 10 occupants were killed, among them the captain. All 12 other occupants were injured, some seriously.

Witnesses reported that the airplane suddenly turned or rolled left until the wings were perpendicular to the ground. The airplane then fell in a nose-down attitude. Examination of the left propeller components indicated a blade angle of about 3°, while the left propeller control unit (pcu) ballscrew position was consistent with a commanded blade angle of 79.2°. Extreme wear on the pcu quill spline teeth, which normally engaged the titanium-nitrided splines of the propeller transfer tube, was found. The titanium-nitrided surface was much harder and rougher than the nitrided surface of the quill. Therefore, the transfer tube splines acted like a file and caused abnormal wear of the gear teeth on the quill. Wear of the quill was not considered during the certification of the propeller system. The aircraft was totally destroyed upon impact and all 23 occupants were killed, among them John Goodwin Tower, Senator of Texas and the astronaut Manley Sonny Carter.

On approach to San Pedro Airport runway 06, the aircraft was number 2 for landing. A Cessna 207, V3-HER was ahead and had broadcast its intention to land. A Tropic Air Twin Otter, call sign Tango Alfa, on the ground, requested that N402BL go around to allow Tango Alfa to takeoff because the ramp was full. N402BL acknowledged and was seen making a left turn with wheels down. No further communication was heard from N402BL. The aircraft was seen flying very low with wheels down and flaps down in a southerly direction and as it crossed the shoreline south of the airstrip the aircraft made a sharp left turn and crashed into the sea about 200 yards from the beach at approximately 1500 hours. The aircraft struck nose first then righted itself and sank in water about five feet deep. There was no fire. Boats in the vicinity reached the accident site within a few minutes and reported that all eight occupants were dead inside the aircraft.

After liftoff from Khartoum-Haj Yussuf Airport, while in initial climb, the crew raised the landing gear when the captain realized that the aircraft did not get a positive rate of climb. He decided to land back on the runway when the aircraft landed on its belly and slid for few dozen meters before coming to rest. All 27 occupants escaped uninjured. The aircraft was written off.

Following a wrong approach configuration, the crew passed over the runway threshold at a height of 30 meters and an excessive speed of 350 km/h. Rather than initiating a go-around procedure, the pilot-in-command continued and the aircraft landed 710 meters past the runway threshold. Unable to stop within the remaining distance, the aircraft overran at a speed of 225 km/h, lost its undercarriage then slid for about 317 meters and eventually collided with concrete blocks (2 meters high), bursting into flames. 29 passengers were injured while 34 other occupants were killed, among them all four crew members.