La Paz

During the takeoff roll from runway 02, at a speed of about 100 km/h, the aircraft became unstable. The pilot-in-command elected to takeoff twice but the aircraft failed to respond. Twelve seconds later, the captain decided to abandon the takeoff procedure but this decision was taken too late as the remaining distance was 300 metres only. Unable to stop, the aircraft crossed the boundary fence then a motorway where it collided with several vehicles before coming to rest, bursting into flames. All three crew members were killed as well as seven people on the ground. Ten other people on the ground were seriously injured.

Following an uneventful cargo flight from La Paz (Mexico), the crew was approaching Culiacán Rosales-Federal de Bachigualato Airport. On final, the aircraft crashed onto several houses located less than one km from runway the threshold. Both pilots were killed while there were no casualties on the ground despite several houses were destroyed by fire. For unknown reasons, the crew was completing the approach at an unsafe altitude.

The aircraft was flying back to Paraná (Argentina) with an intermediate stop at Santa Cruz with 3 military personnel and 3 technicians and board. They came in La Paz to deliver humanitarian aids after important flood in Bolivia. Shortly after takeoff, while in initial climb, the aircraft entered an uncontrolled descent and crashed in an open field located 20 km from La Paz-El Alto Airport. All six occupants were killed.

The aircraft was on an IFR clearance and climbing through a cloud layer when it broke up in flight following an in-flight upset. The weather conditions included multiple cloud layers from 4,000 to 13,000 feet, with a freezing level around 7,000 feet msl. An AIRMET was in effect for occasional moderate rime to mixed icing-in-clouds and in-precipitation below 18,000 feet. As the airplane began to intercept a victor airway, climbing at about 2,000 feet per minute (fpm), and passing through 6,700 feet, the airplane began a series of heading and altitude changes that were not consistent with its ATC clearances. The airplane turned right and climbed to 8,600 feet, then turned left and descended to 8,000 feet. The airplane then turned right and climbed to 8,500 feet, where it began a rapidly descending right turn. At 1034:33, as the aircraft was descending through 7,000 feet, the pilot advised ATC "four Juliet victor I just lost my needle give me..." No further transmissions were received from the accident airplane and the last radar return showed it descending through 3,200 feet at about 11,000 fpm. Analysis of radar data shows the airplane was close to Vmo at the last Mode C return. Ground witnesses saw the airplane come out of the clouds in a high speed spiral descent just before it broke up about 1,000 feet agl. Examination of the wreckage showed that all structural failures were the result of overload. The aircraft was equipped with full flight instruments on both the left and right sides of the cockpit; however, the flight director system attitude director indicator and horizontal situation indicator were only on the left side. The aircraft was also equipped for flight into known icing conditions, with in part, heated pitot tubes (left and right sides), static sources, and stall warning vanes. During the on-scene cockpit examination, except for the pitot heat switches, the cockpit controls and switches were found to be configured in positions consistent with the aircraft's phase of flight prior to the in-flight upset. The right pitot heat switch was found in the ON position, while the left switch was in the OFF position. The left pitot heat switch toggle lever was noticeably displaced to the left by impact with an object in the cockpit. With the exception of the left pitot heat, the anti-ice and deice system switches were all configured for flight in icing conditions. The pitot heat switches, noted to be of the circuit breaker type (functions as both a toggle switch and circuit breaker), were removed from the panel and sent to a laboratory for examination and testing. Low power stereoscopic examination of the switches found that the right switch was intact, while the toggle lever mechanism of the left switch was broken loose from the housing. Microscopic examination of the left switches housing fracture surface revealed imbedded debris and wear marks indicative of an old fracture predating the accident. The broken left switch could be electrically switched by physically holding the toggle lever mechanism in the appropriate ON or OFF position. The electrical contact resistance measurements of the left switch varied between 0.3 and 1.4 ohms, and was noted to be intermittently open with the switch in the ON position. Both switches were then disassembled. While particulate debris was found in both switches, the left one had a significant amount of large coarse fibrous lint-like debris. The flexible copper conductor of the left switches circuit breaker section had several broken strands, and the electrical contacts were dirty. The laboratory report concluded that the left switches toggle was bent to the left in the impact sequence; however, the housing fracture predated the accident and allowed an internal build-up of large coarse fibrous lint-like debris. The combined effects of the broken housing, the resulting misalignment of the toggle mechanism, the dirty contacts, and the large coarse lint debris prevented reliable electrical switching of the device and presented the opportunity for intermittently open electrical contacts. Continuity of the plumbing from the pitot tubes and static ports to their respective instruments was verified. Electrical continuity was established from the bus power sources through the circuit breakers and switches to the heating elements of the pitot tubes and static sources. The heating elements were connected to a 12-volt battery and the operation of the heating elements verified.

After landing, the single engine aircraft deviated to the right, causing the right main gear to struck a ditch and to be torn off. The aircraft came to rest on its belly and was damaged beyond repair. All seven occupants escaped with minor injuries.

While approaching La Paz-El Alto Airport, the airplane struck the slope of a mountain located 15 km from the airfield. The aircraft was destroyed and all three crew members were killed. For unknown reasons, the crew was completing the approach at an insufficient altitude.

Few minutes after takeoff from La Paz-El Alto Airport, while climbing, the airplane crashed in unknown circumstances 14 km from the airport. All seven occupants were killed.

The crew was completing a flight from Howard AFN, Panama, to La Paz. While descending to La Paz-El Alto Airport, the crew encountered poor weather conditions with limited visibility due to clouds from 700 to 24,000 feet. The crew informed ATC about his position about three minutes from La Paz VOR when he was cleared to descend from 24,000 to 18,000 feet. Shortly later, while flying at an altitude of 18,700 feet, the airplane struck the slope of a mountain (20,000 feet high) located 28 km north of El Alto Airport. The airplane disintegrated on impact and all seven crew members were killed.

While in cruising altitude between Santa Rosa and La Paz in poor weather conditions, the airplane disappeared from radar screens. The crew was unable to send any distress call. SAR operations were initiated but were eventually suspended few days later as no trace of the aircraft nor the 24 occupants was found. It is believed the aircraft crashed in an isolated mountainous area following a possible navigation error due to poor weather conditions.

While cruising in poor weather conditions on a cargo flight from San Borja to La Paz, the airplane struck the slope of a mountain located in the region of Unduavi. SAR operations were conducted but eventually suspended few days later as no trace of the airplane was found. The wreckage was located in August 1974. There were no survivors.