Air Transat Flight 236

Air Transat Flight 236 was a transatlantic flight bound for Lisbon, Portugal, from Toronto, Canada, that lost all engine power while flying over the Atlantic Ocean on August 24, 2001. The Airbus A330 ran out of fuel because of a fuel leak caused by improper maintenance. Captain Robert Piché, 48, an experienced glider pilot, and First Officer Dirk DeJager, 28, glided the plane to a successful emergency landing in the Azores, saving all 306 people (293 passengers and 13 crew) on board. Most of the passengers on the flight were Canadians visiting Europe or Portuguese expatriates returning to visit family in Portugal. This was also the longest passenger aircraft glide without engines, gliding for nearly 75 mi. Following this unusual aviation accident, this aircraft was nicknamed the "Azores Glider".

Aircraft
The aircraft involved was an Airbus A330-243, manufacturer serial number 271, registered as C-GITS. The aircraft had its maiden flight in 1999 and was delivered to Air Transat on April 28, 1999. The aircraft was just over two years old and was equipped with two Rolls-Royce Trent 772B-60 engines.

Incident
Flight 236 took off from Toronto at 00:52 (UTC) on Friday, August 24, 2001 (local time: 20:52 (ET) on Thursday, August 23), bound for Lisbon, Portugal, with 293 passengers and 13 crew on board. The flight was flown by Captain Robert Piché, who had 16,800 hours of flight experience (with 796 of them on the Airbus A330), and First Officer Dirk DeJager, who had 4,800 flight hours (including 386 hours on the Airbus A330). The aircraft was a two-year-old Airbus A330-243 registered as that had first flown on March 17, 1999, configured with 362 seats and placed in service by Air Transat on April 28, 1999. It was powered by two Rolls-Royce Trent 772B-60 engines each capable of delivering 71100 lbf thrust. Leaving the gate in Toronto, the aircraft had 46.9 t of fuel on board, 4.5 t more than required by regulations.

At 04:38 UTC (almost four hours into the flight), the aircraft began to leak fuel through a fracture that had developed in a fuel line to the no. 2 (right) engine. At 05:03 UTC, more than four hours into the flight, the pilots noticed low oil temperature and high oil pressure on engine no. 2. Although these readings were an indirect result of the fuel leak, the pilots had no reason  to consider that as a cause. Consequently, Captain Piché suspected they were false warnings and shared that opinion with Air Transat maintenance control centre in Montreal, which advised them to monitor the situation.

Indications of a fuel problem

 * 1) The fuel on board was decreasing at an unusual rate which was displayed in the Fuel-On-Board (FOB) quantity on the Engine Warning Display.
 * 2) The estimated fuel on board at destination would have been showing as decreasing indicating reduced fuel range.
 * 3) The full forward transfer of the fuel in the trim tank was premature given the fuel load on departure from Toronto of 46900 kg. A prolonged, 19-minute TRIM TANK XFR memo between 05:11 and 05:30, and then the TRIM TANK XFRD memo between 05:30 and 05:33 would have displayed this information.

At 05:36 UTC, the pilots received a warning of fuel imbalance.

Rather than referring to the appropriate checklists, the crew actioned procedures from memory, and this resulted in the cross-feeding of fuel into an already leaking engine.

The transferred fuel was lost through the fractured fuel line, which was leaking at about 13 tonnes per hour (more than 3.6 kg/s). This caused a higher-than-normal fuel flow through the fuel-oil heat exchanger, which in turn led to a drop in oil temperature and a rise in oil pressure for the no. 2 engine.

At 05:45 UTC, the pilots decided to divert to Lajes Air Base in the Azores. They declared a fuel emergency with Santa Maria Oceanic air traffic control three minutes later.

At 06:13 UTC, while still 150 nmi from Lajes and at 39000 ft, engine no. 2 flamed out from fuel starvation. Piché then initiated a descent to 33000 ft, which was the proper single-engine altitude for the weight of the plane at that time. Ten minutes later, the crew sent a mayday to Santa Maria Oceanic air traffic control.

Thirteen minutes later, at 06:26 UTC and about 65 nmi from Lajes Air Base, engine no. 1 also flamed out, requiring the plane to glide the remaining distance. Without engine power, the plane lost its primary source of electrical power. The emergency ram air turbine deployed automatically to provide essential power for critical sensors and flight instruments to fly the aircraft as well as enough hydraulic pressure to operate the primary flight controls (without which the aircraft would be uncontrollable). The aircraft lost hydraulic power for the flaps, alternate brakes, and spoilers. The slats would still be powered, while the primary brakes would be able to operate a limited number of times using pressure stored in the brake accumulator. With neither engine running, there was no source of bleed air to maintain cabin pressurization. Five minutes later, at 06:31 UTC, the oxygen masks dropped down in the passenger cabin.

Military air traffic controllers guided the aircraft to the airport with their radar system. The descent rate of the plane was about 2000 ft/min. They calculated they had about 15 to 20 minutes left before they would be forced to ditch in the ocean. The air base was sighted a few minutes later. Piché executed one 360° turn, and then a series of "S" turns, to dissipate excess altitude.

At 06:45 UTC, the plane touched down hard, around 1030 ft past the threshold of runway 33, at a speed around 200 kn, bounced once, and then touched down again, roughly 2800 ft from the threshold. Maximum emergency braking was applied and retained, and the plane came to a stop after a landing run that consumed 7600 ft of the 10000 ft runway. Because the antiskid and brake modulation systems were inoperative, the eight main wheels locked up, the tires abraded and fully deflated within 450 ft, and the wheels themselves were worn down to the axle journals during rollout.

Fourteen passengers and two crew members had minor injuries, while two passengers had serious injuries during the evacuation of the aircraft. The plane suffered structural damage to the main landing gear (from the hard touchdown and the abrasion of the locked wheels against the runway surface during the landing roll) and the lower fuselage (both structural deformation from the hard touchdown and various punctures from impact by pieces of debris shed from the main landing gear).

Investigation
The Portuguese Aviation Accidents Prevention and Investigation Department (GPIAA) investigated the accident along with Canadian and French authorities.

The investigation revealed that the primary causal factors of the accident were crew actions in mishandling a fuel leak in the no. 2 engine.

The fuel leak resulted from fitment of an incorrect part to the hydraulics system by Air Transat maintenance staff as part of routine maintenance. The engine had been replaced with a spare engine, lent by Rolls-Royce, from an older model which did not include a hydraulic pump. Despite the lead mechanic's concerns, Air Transat authorized the use of a part from a similar engine, an adaptation that did not maintain adequate clearance between the hydraulic lines and the fuel line. This lack of clearance, of the order of millimetres from the intended part, allowed chafing between the lines to rupture the fuel line, causing the leak.

Air Transat accepted responsibility for the accident and was fined C$250,000 by the Canadian government, which  was the largest fine in Canadian history.

The conclusions reached in the accident report revealed that:


 * The flight crew did not detect that a fuel problem existed until the Fuel ADV advisory was displayed and the fuel imbalance was noted on the Fuel ECAM page.
 * The crew did not correctly evaluate the situation before taking action.
 * The flight crew did not recognize that a fuel leak situation existed and carried out the fuel imbalance procedure from memory, which resulted in the fuel from the left tanks being fed to the leak in the right engine.
 * Conducting the FUEL IMBALANCE procedure by memory negated the defence of the Caution note in the FUEL IMBALANCE checklist that may have caused the crew to consider timely actioning of the FUEL LEAK procedure.
 * Although there were a number of other indications that a significant fuel loss was occurring, the crew did not conclude that a fuel leak situation existed – not actioning the FUEL LEAK procedure was the key factor that led to the fuel exhaustion.

Nevertheless, the pilots returned to a heroes' welcome from the Canadian press as a result of their successful unpowered landing. In 2002, Captain Piché was awarded the Superior Airmanship Award by the Air Line Pilots' Association.

Aftermath
Following the accident investigation, the French Directorate General for Civil Aviation (DGCA) issued F-2002-548B, requiring a detailed fuel-leak procedure in the flight manual and the need for crews to be aware of this. This was later cancelled and replaced by F-2005-195. The US Federal Aviation Administration (FAA) issued AD 2006-02-01, effective February 3, 2006, requiring new airplane flight manual procedures to follow in the event of a fuel leak for Airbus Model A330 and A340 aircraft.

The accident led to the DGCA and FAA issuing an airworthiness directive (AD), requiring all operators of Airbus models A318, A319, A320 and A321 narrow-body aircraft to revise their flight manuals, stressing that crews should ensure that any fuel imbalance is not caused by a fuel leak before opening the cross-feed valve. The AD required all airlines operating these Airbus models to make revisions to the flight manuals before any further flights were allowed. The FAA gave a 15-day grace period before enforcing the AD. Airbus also modified its computer systems; the on-board computer now checks all fuel levels against the flight plan. It now gives a clear warning if fuel is being expended beyond the specified fuel consumption rate of the engines. Rolls-Royce also issued a bulletin advising of the incompatibility of the relevant engine parts.

The aircraft was repaired and returned to service with Air Transat in December 2001, with the nickname "Azores Glider". It was placed into storage in March 2020 because of the COVID-19 pandemic. On October 18, 2021, the aircraft made its last flight with Air Transat and was subsequently returned to the lessor AerCap. The aircraft was re-registered as N271AD and stored at Pinal Airpark. The future use of the aircraft is unknown.

Related study
Margaret McKinnon, a postdoctoral psychology student at Baycrest Health Sciences in Toronto at the time, was a passenger on her honeymoon on Flight 236. She and her colleagues recruited 15 other passengers in a study of post-traumatic stress disorder (PTSD), published in August 2014 in the academic journal Clinical Psychological Science, which compared details recalled by passengers with PTSD with those recalled by passengers without PTSD and with a control group.

Dramatizations

 * The events of Flight 236 were featured in "Flying on Empty", a season-one (2003) episode of the Canadian TV series Mayday (called Air Emergency and Air Disasters in the U.S. and Air Crash Investigation in the UK and elsewhere around the world). The flight was also included in a Mayday sixth season (2007) Science of Disaster special titled "Who's Flying the Plane?"
 * MSNBC produced a report on the incident with the title "On a Wing and a Prayer", which first aired in the U.S. on August 7, 2005.
 * The story of Robert Piché is depicted in the 2010 French Canadian biographical drama film Piché: The Landing of a Man culminating with the events on Flight 236. Captain Piché is portrayed by both Genie Award-winning actor Michel Côté and his son Maxime LeFlaguais.