Cargo

The captain's decision to continue with the flight with a malfunctioning left engine propeller control and the subsequent loss of engine power on both engines for undetermined reasons, which resulted in ditching into the ocean. Contributing to the accident was the first officer's failure to challenge the captain's decision to continue with the flight.

The flight was undertaken with an airplane whose center of gravity was beyond the rear center of gravity limits and a mass greater than the maximum take-off mass. The load was not secured. As a result, the performance of the aircraft was degraded and piloting made more difficult. The BEA investigation did not reveal any major failure that could explain a loss of power. Engine performance may have been lower than the manufacturer's standards, due in particular to improper adjustment of the mechanical fuel pump, probably resulting from unsuitable maintenance. This defect was most likely already present on previous flights. It is likely that the power required for the initial climb was greater than what the engine could deliver. This brought the aircraft into a situation where the speed gradually decreased. When the pilot turned, the stall warning sounded and the pilot sensed the engine was losing power.

Findings as to causes and contributing factors:
These are conditions, acts or safety deficiencies that were found to have caused or contributed to this occurrence.
1. The ineffective presentation style and sequence of the NOTAMs available to the crew and flight dispatch led them to interpret that Runway 23 was not available for landing at Halifax/Stanfield International Airport.
2. The crew was unaware that the aircraft did not meet the pre-departure landing weight requirements using flaps 25 for Runway 14.
3. Due to the timing of the flight during the nighttime circadian trough and because the crew had had insufficient restorative sleep in the previous 24 hours, the crew was experiencing sleep-related fatigue that degraded their performance and cognitive functioning during the approach and landing.
4. Using unfactored (actual) landing distance charts may have given the crew the impression that landing on Runway 14 would have had a considerable runway safety margin, influencing their decision to continue the landing in the presence of a tailwind.
5. When planning the approach, the crew calculated a faster approach speed of reference speed + 10 knots instead of the recommended reference speed + 5 knots, because they misinterpreted that a wind additive was required for the existing conditions.
6. New information regarding a change of active runway was not communicated by air traffic control directly to the crew, although it was contained within the automatic terminal information service broadcast; as a result, the crew continued to believe that the approach and landing to Runway 14 was the only option available.
7. For the approach, the crew selected the typical flap setting of flaps 25 rather than flaps 30, because they believed they had a sufficient safety margin. This setting increased the landing distance required by 494 feet.
8. The crew were operating in a cognitive context of fatigue and biases that encouraged anchoring to and confirming information that aligned with continuing the initial plan, increasing the likelihood that they would continue the approach.
9. The crew recognized the presence of a tailwind on approach 1 minute and 21 seconds from the threshold; likely due to this limited amount of time, the crew did not recalculate the performance data to confirm that the runway safety margin was still acceptable.
10. An elevated level of stress and workload on short final approach likely exacerbated the performance-impairing effects of fatigue to limit the crew’s ability to determine the effect of the tailwind, influencing their decision to continue the approach.
11. The higher aircraft approach speed, the presence of a tailwind component, and the slight deviation above the glideslope increased the landing distance required to a distance greater than the runway length available.
12. After the firm touchdown, for undetermined reasons, the engine No. 1 thrust lever was moved forward of the idle position, causing the speed brakes to retract and the autobrake system to disengage, increasing the distance required to bring the aircraft to a stop.
13. The right crab angle (4.5°) on initial touchdown, combined with the crosswind component and asymmetric reverser selection, caused the aircraft to deviate to the right of the runway centreline.
14. During the landing roll, the pilot monitoring’s attention was focused on the lateral drift and, as a result, the required callouts regarding the position of the deceleration devices were not made.
15. The pilot flying focused on controlling the lateral deviation and, without the benefit of the landing rollout callouts, did not recognize that all of the deceleration devices were not fully deployed and that the autobrake was disengaged.
16. Although manual brake application began 8 seconds after touchdown, maximum braking effort did not occur until 15 seconds later, when the aircraft was 800 feet from the end of the runway. At this position, it was not possible for the aircraft to stop on the runway and, 5 seconds later, the aircraft departed the end of the runway at a speed of 77 knots and came to a stop 270 m (885 feet) past the end of the runway.
17. During the overrun, the aircraft crossed a significant drop of 2.8 m (9 feet) approximately 166 m (544 feet) past the end of the runway and was damaged beyond repair. While this uneven terrain was beyond the 150 m (492 feet) runway end safety area proposed by Transport Canada, it was within the recommended International Civil Aviation Organization runway end safety area of 300 m (984 feet).

Findings as to risk:
These are conditions, unsafe acts or safety deficiencies that were found not to be a factor in this occurrence but could have adverse consequences in future occurrences.
1. If the pilot monitoring does not call out approach conditions or approach speed increases, the pilot flying might not make corrections, increasing the risk of a runway overrun.

Other findings:
These items could enhance safety, resolve an issue of controversy, or provide a data point for future safety studies.
1. The investigation concluded that there was no reverted rubber hydroplaning and almost certainly no dynamic hydroplaning during this occurrence.
2. Although viscous hydroplaning can be expected on all wet runways, the investigation found that when maximum braking effort was applied, the aircraft braking was consistent with the expected braking on Runway 14 under the existing wet runway conditions.

The pilot's failure to attain the proper touchdown speed and his decision to land with a tailwind without ensuring that there was adequate runway length for the touchdown.

The failure of both pilots to see and avoid the other airplane while in level cruise flight, which resulted in a midair collision.

The Commission determines the most probable cause of this accident was to continue the flight despite unfavorable weather conditions resulting inadvertent flight into instrument
meteorological conditions and there by deviating from the normal track due to loss of situational awareness that aggravated the spatial disorientation leading to CFIT accident. The following contributing factors were reported:
- Possible effect of hypoxia due to flight for prolonged period in high altitude without oxygen supplement,
- Ineffective safety management of the company which prevented the organization from identifying and correcting latent deficiencies in risk management and inadequacies in pilot training.

The pilot's decision to land in a gusty crosswind that exceeded the airplane's maximum demonstrated crosswind and resulted in a runway excursion.