Surprise and hesitation prevailed during the final seconds of an Afriqiyah Airways Airbus A330-202’s approach to Tripoli, Libya, the morning of May 12, 2010. The Libyan Civil Aviation Authority (CAA) has determined that the aircraft was well below the minimum descent altitude for the nonprecision approach when the copilot, the pilot flying (PF), asked the captain if he should initiate a go-around.
Although neither pilot had the required visual references to proceed with the approach, seconds passed as the aircraft continued to descend. Finally, an aural warning generated by the terrain awareness and warning system (TAWS) prompted the captain to command a go-around.
The copilot applied full power and initiated a climb. According to the CAA’s final report, the sensory effects of the A330’s acceleration likely caused the copilot to falsely perceive that the aircraft had entered an excessive nose-up pitch attitude. He moved his sidestick forward, and the climb reversed into a steep descent.
The captain assumed control, but he, too, likely had become spatially disoriented. Instead of pulling out of the dive, he moved his sidestick full forward. Too late, the pilots caught sight of the ground.
The A330 struck terrain close to the runway threshold. “The impact and post-impact fire caused complete destruction to the aircraft,” the report said. Only one of the 104 people aboard the aircraft survived.
The accident occurred during a scheduled 8.5-hour flight from Johannesburg, South Africa, with 93 passengers, eight cabin crewmembers and an augmented flight crew of three pilots. Tripoli is the home base for Afriqiyah Airways, which at the time operated three A330s and six A320 series aircraft.
The accident aircraft was manufactured in 2009. The report said that all three pilots had 516 flight hours in type. They had flown together often and were familiar with the Tripoli airport.
The captain, 57, had a total of 17,016 flight hours. He had flown A320, Boeing 727 and Fokker 28 series aircraft for Libyan Arab Airlines and Nouvel Air before being hired by Afriqiyah Airways as an A320 captain in 2007. He earned an A330 type rating in May 2009.
The copilot, 42, had 4,216 flight hours. He held type ratings in the de Havilland Twin Otter, A320 and A330. The report provided no details about his previous flight experience.
The relief pilot, 37, had 1,866 flight hours and held type ratings in the A320, A330 and 727.
The crew departed from Johannesburg at 2145 local time, with the copilot at the controls. “In general, it is common practice within Afriqiyah Airways to designate the copilot as PF when weather conditions do not result in difficulty in handling the aircraft,” the report said.
The cruise portion of the flight was conducted at Flight Level (FL) 400 (approximately 40,000 ft). “The flight took place without any notable events until the approach,” the report said.
At about 0530, air traffic control cleared the crew to descend to FL 90. The controller said that the weather conditions at Tripoli included calm winds, 6 km (4 mi) visibility, a clear sky and a temperature/dew point of 19/17 degrees C (66/63 degrees F).
The airport had one precision approach, an instrument landing system (ILS) for Runway 27, but it was out of service. The VOR/DME (VHF omnidirectional range/distance-measuring equipment) facility at the airport also was out of service, and only locator approaches were available. The locator approach to Runway 09 was in use.
The report said that the crew conducted a “short” approach briefing that included some details about the locator approach and how it would be flown. However, “essential points,” such as the intended use of the autoflight systems during the nonprecision approach, were not discussed.
“The fact that the approach briefing was incomplete indicates that … the crew did not anticipate any special difficulty in the conduct and management of the approach,” the report said.
The locator approach was based on three compass locators (nondirectional radio beacons) lined up on the extended centerline of Runway 09. The first, identified as “TW,” was 3.9 nm (7.2 km) from the runway threshold and served as an initial approach fix as well as the final approach fix. The other two beacons, located near the approach and departure thresholds, respectively, marked the missed approach point and the turning point for the missed approach procedure.
“Generally, in the Tripoli Terminal Control Area, arrivals are carried out under radar vectoring until intercepting the extended centreline of the final approach segment,” the report said.
Investigators were unable to determine whether the crew conducted the approach checklist. “The approach checklist seemed to be performed, but without any formal callouts,” the report said. “The only item called out by the crew was the altimeter setting.”
The crew established the A330 at 1,400 ft on the final approach course, 090 degrees, about 10 nm (19 km) from the runway. The approach chart the crew was using indicates that the aircraft should have crossed the final approach fix, the TW locator, at 1,350 ft before descending to the minimum descent altitude (MDA) of 620 ft. However, recorded flight data showed that the A330 began an early descent about 1.1 nm (2.0 km) before reaching the final approach fix.
Investigators determined that the copilot might have inadvertently entered the distance from the TW locator to the VOR/DME (5.2 nm), rather than the distance from the locator to the runway (3.9 nm), when he programmed the point at which the flight management system would begin a descent on a three-degree glide path for the final approach.
The aircraft was descending through 1,200 ft when the captain established radio communication with the Tripoli airport traffic controller. The controller asked if the runway was in sight, and the captain replied, “Established inbound, sir.” The controller then told the captain to report the field in sight.
The two-engine A330 and the four-engine A340 were developed simultaneously by Airbus and share many systems and structural features. The base-model A330-300 entered service in January 1994, a few months after the A340.
The A330-200 is an extended-range version of the -300 that was introduced in 1998 with a shorter fuselage and higher fuel capacity. Both models have General Electric CF6-80, Pratt & Whitney PW 4000 or Rolls-Royce Trent 700 series turbofan engines rated at about 70,000 lb (31,752 kg) thrust.
The A330-200 accommodates 253 passengers in a twin-aisle cabin and has maximum weights of 230,000 kg (507,063 lb) for takeoff and 180,000 kg (396,832 lb) for landing. Typical operating speed is 0.82 Mach, and maximum range with reserves is 6,650 nm (12,316 km).
In 2012, maximum takeoff weight was increased to 240,000 kg (529,109 lb) to accommodate extra fuel capacity and increase range to 7,050 nm (13,057 km).
Currently, 484 A330-200s are in operation worldwide.
Sources: Airbus, Jane’s All the World’s Aircraft
Shortly thereafter, the pilots heard a radio transmission by the crew of a preceding aircraft advising that they had encountered patches of fog on short final before landing. This likely surprised the A330 crew and “led the captain to focus his attention on the outside to acquire visual reference points, rather than on coordinating with the copilot and monitoring the flight parameters,” the report said. “Overall, the management of tasks during the approach deteriorated very quickly.”
Although the relief pilot was in the jump seat during the approach, there was no evidence that he said anything or interacted with the other pilots in any way.
The aircraft was configured for landing when the copilot called for the landing checklist. However, this “could not be applied at this moment in time due to exchanges between the PNF [pilot not flying] and the tower controller,” the report said.
The aircraft crossed the TW locator at 1,020 ft — 330 ft below the published crossing altitude — at 0600:01. Neither pilot apparently recognized the discrepancy.
The captain was engaged in obtaining a landing clearance. He asked the controller, “Confirm clear to land if we have the runway in sight?” The controller replied, “Affirmative. Clear to land. Wind calm.”
A few seconds later, the cockpit voice recorder captured an automated callout of “hundred above,” indicating that the aircraft was 100 ft above the MDA. The copilot asked in Arabic, “You see?”
The captain replied, “Continue.”
Company standard operating procedures (SOPs) define the “continue” callout as indicating that the PNF has acquired the visual references required to complete the approach and landing. “However, it is almost certain that the weather conditions (as indicated by the previous crew), the lighting conditions and the actual position of the aircraft in relation to the runway threshold … did not enable acquisition of the external visual references required to continue the approach below the MDA,” the report said. “The captain … probably hoped to obtain visual references in the next few seconds.”
Moreover, because the crew of the preceding aircraft had been able to land despite the developing fog, the A330 crew might have been confident that they also would be able to land, the report said.
Shortly after the copilot acknowledged the captain’s instruction to continue the approach, an automated callout advised that the aircraft had reached the “minimum,” the MDA at 620 ft, or 358 ft above ground level (AGL).
Neither pilot said anything for several seconds. The copilot likely looked up from the instruments and, not seeing the runway, asked, “I’ll go around, captain?” There was no immediate reply. The report noted that the copilot did not initiate a go-around on his own volition, as required by SOPs.
The aircraft was descending through 490 ft — 228 ft AGL — when the TAWS generated the “TOO LOW TERRAIN” warning.
“Go around,” the captain said. “Go around. Go around.” The copilot disengaged the autopilot, applied takeoff/go-around power, pulled his sidestick back and asked the captain to retract the flaps and landing gear.
“The captain, as PNF, did not make the appropriate callouts,” the report said. “It is likely that the captain did not expect to have to abort the final approach and the ‘TOO LOW TERRAIN’ warning [had] destabilized him,” the report said.
Four seconds after disengaging the autopilot and initiating a climb, the copilot began to apply nose-down pitch inputs on his sidestick. The aircraft, which had climbed to 670 ft, entered a steep descent.
The report said that the copilot likely had suffered spatial disorientation “typical of a somatogravic [perceptual] illusion occurring in the absence of outside visual references.” This would have resulted from the aircraft’s sudden acceleration affecting the balance organs of his inner ear, creating a sensation of being tilted backward and the false perception that the pitch attitude was excessive (although it wasn’t).
His reactions likely responded to the illusion, rather than to the flight instruments. “At no time was the go-around pitch attitude controlled, nor did the copilot follow the instructions from the flight director,” the report said. “Neither crewmember seemed to be aware of the flight path of the aircraft.”
As the A330 descended, the TAWS generated successive warnings of “DON’T SINK,” “TOO LOW TERRAIN” and “PULL UP.” Nevertheless, seconds before impact, the captain pressed the priority pushbutton on his sidestick and applied a “sharp nose-down input,” the report said.
The pitch attitude was 3.5 degrees nose-down as the aircraft descended through 500 ft. By this time, the copilot apparently had become aware of the aircraft’s flight path and had pulled his sidestick all the way back, intending to recover from the dive but not recognizing that the captain had sidestick priority. The captain had not announced that he was assuming flight control.
Shortly before impact, the captain apparently became aware of the aircraft’s proximity to the ground and reversed his sidestick input. The descent rate was 4,400 fpm when the A330 clipped trees and a high-tension power line, and struck the ground in a nearly level attitude at 0601:14. The impact occurred 1,200 m (3,937 ft) from the runway and slightly to the right of the extended centerline.
“Postmortem examination of the victims indicated that all fatalities resulted from severe trauma,” the report said. Media accounts said that the survivor was a 9-year-old Dutch boy. He suffered serious injuries and was hospitalized in Tripoli for 48 hours before being transferred to a hospital in the Netherlands.
Investigators determined that fatigue might have been a factor in the accident, though the evidence was not conclusive. All three pilots had received more than 15 hours of rest before reporting for duty at Johannesburg. Moreover, the captain had taken a rest period during cruise flight, returning to the cockpit at 0410, almost two hours before the accident occurred. The report said that the copilot and the relief pilot likely took their rest periods before the captain.
However, the pilots had flown two consecutive night flights. “This would impose a certain amount of fatigue which might [have] degraded the performance of the flight crew and increased the effect of somatogravic illusions,” the report said.
“The pilots’ performance was likely impaired [by] fatigue, but the extent of their impairment and the degree to which it contributed to the performance deficiencies that occurred during the flight cannot be conclusively determined.”
Lessons Not Learned
The report noted that a similar event had occurred 14 days before the accident: The captain and the copilot had conducted the same locator approach in the same aircraft on April 28. The approach was similar in having been unstabilized and marked by a premature descent. However, it terminated with a missed approach initiated slightly above the MDA and was followed by an uneventful go-around and landing on Runway 27.
The crew did not report the go-around, as required, to Afriqiyah Airways. “The investigation committee confirmed that analysis of the April 28 flight was not performed … and the crew had not reviewed and fully understood what had happened during the April 28 flight,” the report said.
This article is based on the Libyan Civil Aviation Authority’s “Final Report of Afriqiyah Airways Aircraft Airbus A330-202, 5A-ONG, Crash Occurred at Tripoli (Libya) on 12/05/2010,” February 2013. The report is available at <caa.ly>.