Tuesday 6th February 1996 marks the date of the Birgenair Flight 301 crash, the Dominican Republic’s deadliest aviation disaster, which led to the loss of 189 lives.
Birgenair Flight 301 – A Brief Introduction
The Birgenair Flight 301 disaster, one of the deadliest ever incidents involving a Boeing 757, happened on this day in 1996. Erroneous airspeed indicators led to the captain and first officer losing control of the plane. It is believed that one of the plane’s pilot tubes was blocked by mud dauber wasps, which set in motion a chain of events that led to the plane crashing into the Atlantic Ocean.
Birgenair was a Turkish charter airline established in 1988. The airline developed close ties with Öger Tours, a German tour operator, and Alas Nacionales, a carrier based in the Dominican Republic.
Birgenair Flight 301, charted by Alas Nacionales, was scheduled to depart from Gregorio Luperón International Airport (POP), Puerto Plata, in the Dominican Republic to Frankfurt Airport (FRA), Germany, with stopovers at Gander International Airport (YQX), Newfoundland and Labrador, Canada, and Berlin Schönefeld Airport (BER), Germany.
The Aircraft And Crew
The plane involved in the crash was a Boeing 757-255 manufactured in 1985, and it had accumulated 29,269 service hours and 13,499 cycles. Prior to the crash, it had not been flown for 20 days, and the pitot tubes had been left uncovered for the duration. Pitot tubes are used to measure factors such as a plane’s altitude and airspeed.
Due to the length of the flight, a captain (the pilot in command), a relief captain and a first officer were present. The three flight pilots were all medically authorised to operate the plane. It was noted, however, that the flight crew may not have been fully rested and prepared to fly as they had been unexpectedly called up during their scheduled downtime.
The Passengers Lost In The Disaster
The Birgenair Flight 301 disaster involved a total of 189 people, including 176 passengers and 13 crew members. Of the passengers, 167 were German nationals, and 9 were Polish nationals. The 13 crew members consisted of 11 Turkish nationals, and 2 Dominican nationals.
Of the Polish nationals, two Members of Parliament also lost their lives: Zbigniew Gorzelańczyk of the Democratic Left Alliance and Marek Wielgus of the Nonpartisan Bloc for Support of Reforms (BBWR).
All the passengers died on impact, and conditions hampered the recovery of bodies at the location of the wreckage.
Prelude To The Fatal Crash
On the day of the crash, shortly after take-off, the captain alerted the first officer to the fact that his airspeed indicator (ASI) was not working. The first officer noted, however, that his airspeed indicator was operating as normal.
The captain requested the first officer only to call out the airspeeds on the latter indicator. Despite the indicator issues and in contravention of established procedures, the captain continued with take-off, and the autopilot lateral navigation (LNAV) mode was engaged.
Shortly after, the captain noted to the first officer that his airspeed indicator was once again in operation. The crew set climb thrust, engaged the autopilot vertical navigation (VNAV) mode, and continued with take-off. The centre autopilot was then engaged.
Unbeknown to the pilots at the time, the erroneous airspeed indicators were the result of an obstruction in one of the aircraft’s three pitot tubes. Despite the initial error readings, as the aircraft climbed, the airspeed indicators began to work due to the expansion of thinning air within the pitot tubes causing pressure to build up.
The Final Moments Of Birgenair Flight 301
As the flight progressed, the fault with the airspeed indicators made it impossible for the pilots to determine whether the plane was travelling at the appropriate speed.
According to the recovered cockpit voice recorder transcript, the captain stated, “Rudder ratio, mach airspeed trim.” This statement was made in reference to two messages that had appeared on the engine indication and crew alerting system (EICAS) display. Their simultaneous appearance indicated that there was a discrepancy between the captain’s airspeed indicator readings and those of the first officer. As the flight continued, discrepancies arose between the captain’s and the first officer’s airspeed indicators, with them showing 327 knots and 200 knots and decreasing, respectively.
Due to the overestimated airspeed indicator readings, the autopilot system reduced the plane’s speed and pitched its nose upwards. Following the disengagement of the autopilot, the pilots reduced the thrust. At this point, the aircraft began to stall, and in an attempted countermeasure, the pilots increased the thrust; however, these efforts proved futile as the plane’s left-hand engine had stopped working, and only the right-hand engine was in operation at that point.
The actions taken by the pilots to prevent the plane from stalling eventually failed, and five minutes into the flight, the aircraft crashed into the Caribbean Sea just off the coast of the Dominican Republic. The destroyed aircraft sank to a depth of 7,200 feet.
Crash Investigation Conclusions
On 28th February 1996, the plane’s cockpit voice recorder (CVR) and flight data recorder (FDR) were recovered by the U.S. Navy and were analysed by the U.S. National Transportation Safety Board. The CVR data confirmed that the pilots had experienced issues with their airspeed indicators and that they struggled to regain control of the aircraft as it began to stall.
The Dominican Civil Aviation Accident Investigation Board/Junta Investigadora de Accidentes Aéreos (JIAA) conducted an investigation into the crash, and in its final report, the cause of the crash was summarised as follows:
“The failure on the part of the flight crew to recognise the activation of the stick shaker as an imminent warning of [an] aerodynamic stall and their failure to execute proper procedures for recovery [from] the control loss.”
The Presumed Cause Of The Crash — Mud Dauber Wasps
Toxicology tests showed that none of the passengers had inhaled combustible vapours or carbon monoxide, and no evidence of fire was found in the wreckage or the recovered bodies; thus, a pre-impact fire or explosion was ruled out. In addition, the meteorological conditions and the forecast for the area at the time were favourable; therefore, weather-related influences were presumed not to have played a role in the Birgenair Flight 301 crash.
Although the wreckage itself, including the pitot tubes, was not recovered, and it was not possible to properly verify the cause of the crash, investigators surmised that the crash was caused by nesting mud dauber wasps (Sceliphron caementarium) inside one of the uncovered pitot tubes. The presence of the wasps, which are a well-known threat to aviation safety in the Dominican Republic, and the fact that no measures were taken to remove them during ground checks meant that the tubes were consequently unable to feed the captain’s speed indicator, which led to its malfunction and the resultant crash.
The Aftermath Of The Crash
Due to the negative publicity surrounding the Birgenair Flight 301 disaster and a resultant drop in revenues, Birgenair ceased operations in the same year of the crash after filing for bankruptcy.
Following the release of the JIAA’s accident investigation report, several recommendations were made to the United Nations International Civil Aviation Organisation (ICAO), including:
• The issuing of a directive requiring the flight manual of the B-757/767 to be revised to notify pilots that simultaneous activation of the warnings “mach/speed trim” and “rudder ratio” may be an indication of airspeed discrepancies;
• A requirement for Boeing Co. to modify the B-757/767 alert system with the inclusion of an advisory (“caution alert”) when an erroneous airspeed is detected and for the company to modify the manual of the B-757/767 to include information about the identification and elimination of an erroneous airspeed indication in the emergency procedures section;
• Provision for all training in B-757/767 aircraft to include a scenario flight in a simulator where the pilot is trained to respond to the effects of a blocked pitot tube appropriately;
• Establishment of a flight crew training program in crew resource management (CRM) for all commercial air businesses.
Recent Plane Crash Tragedies
The deadliest plane disaster of 2023 (to date) took place on Sunday 15th January, when Yeti Airlines Flight 691 crashed into a gorge of the Seti Gandaki River near the resort town of Pokhara, Nepal; all of the passengers and crew members on board were killed. Although the exact cause of the crash has not yet been established, aviation experts point to ground footage taken before the crash indicating that the plane went into a stall before its descent, similar to the presumed events involved in the Birgenair Flight 301 crash. Aviation safety experts have also sighted Nepal’s mountainous terrain and variable weather conditions as problematic factors for safe flying within the country.
Two deadly crash incidents also occurred in November 2022: one in Peru and one in Tanzania.
At Jorge Chávez International Airport (LIM) in Lima, Peru, a LATAM Airlines aircraft attempting to take off crashed into a fire engine that was on the airport’s runway. Although none of the passengers on board the plane were fatally injured, two firefighters who were seated in the fire engine lost their lives. The reason for the vehicle’s presence on the runway was not clear at the time; however, it was later revealed that the vehicle had been taking part in an authorised accident training exercise. The crash is believed to have been the result of miscommunication between the Peruvian Corporation of Commercial Airports and Aviation (CORPAC) and the local air traffic control authority.
In Tanzania, a Precision Air plane that had taken off from the country’s capital Dar es Salaam and was en route to the lakeside town of Bukoba, crashed into Victoria Lake, Africa’s largest lake. The aircraft had been flying in deteriorating weather conditions, including intense rainfall, and the surviving passengers noted that the plane shook violently before the fatal crash. The aircraft’s pilot and first officer were killed in the crash, and of the 43 passengers, 19 lost their lives. The remaining 24 passengers and the two flight attendants survived. Emergency services were criticised for their delayed response to the crash, with the country’s Ministry of Transport stating that more lives could have potentially been saved had their response been more prompt.
Do you remember the Birgenair Flight 301 disaster? Let us know in the comments.