Gander

Findings as to causes and contributing factors:
1. Neither pilot had considered that the combination of landing at night, in reduced visibility, with a crosswind and blowing snow, on a runway with no centreline lighting, was a hazard that may create additional risks.
2. The blowing snow made it difficult to identify the runway centreline markings, thereby reducing visual cues available to the captain. This situation was exacerbated by the absence of centreline lighting and a possible visual illusion caused by blowing snow.
3. Due to the gusty crosswind conditions, the aircraft drifted to the right during the landing flare, which was not recognized by the crew.
4. It is likely that the captain had difficulty determining aircraft position during the landing flare.
5. The flight crew’s decision to continue with the landing was consistent with plan continuation bias.
6. During landing, the nosewheel struck the compacted snow windrow on the runway, causing the nose landing gear to collapse.

Findings as to risk:
1. If aircraft are not equipped with a 406 MHz-capable emergency locator transmitter, flight crews and passengers are at increased risk of injury or death following an accident because search-and-rescue assistance may be delayed.
2. If operators do not have defined crosswind limits, there is a risk that pilots may land in crosswinds that exceed their abilities, which could jeopardize the safety of flight.
3. If composite propeller blades contact objects and separate, and then strike or penetrate the cabin, there is a risk of injury or death to occupants seated in the propeller’s plane of rotation.
4. If modern crew resource management training is not a regulatory requirement, then it is less likely to be introduced by operators and, as a result, pilots may not be fully prepared to recognize and mitigate hazards encountered during flight.
5. If organizations do not use modern safety management practices and do not have a robust safety culture, then there is an increased risk that hazards will not be identified and mitigated.
6. When testing an emergency locator transmitter’s (ELT) automatic activation system, a sticking g-switch may go undetected if more than 1 football throw is necessary to activate the ELT. As a result, the ELT might not activate during an accident, and search-and-rescue assistance may be delayed, placing flight crews and passenger at an increased risk for injury or death.

This was a private flight which could not depart in conditions of less than 400 m RVR. RVR cannot be measured at the threshold end of Runway 03 but the prevailing visibility was reported as being more than 10 km. The crew reported that there was moisture on the windscreen from the mist and they could see a “glow” around lights which were visible to them. They were also aware while taxiing that there was some patchy ground fog on the airfield. The ATC controller transmitted that visibility had not been measured in the fog patches but there seemed to be ‘very low, very thin fog from the zero three threshold to approximately half way down the runway’. With hindsight, this piece of information is significant but, at the time, the crew did not consider the fog to be widespread or thick; operating under FAR Part 91 in the United States, they were used to making their own judgments as to whether the visibility was suitable for a takeoff. However, after the aircraft came to a halt following its abortive takeoff attempt, the controller could only see the top of the fuselage and tail above the layer of fog. It is likely, therefore, that the visibility was worse than the crew appreciated at the time N103CD taxied from Holding Point J1. The route from J1 to the runway The information on the aerodrome chart used by the crew, and the source of information in the UK AIP, suggested that the aircraft would be required to taxi in a straight line from J1 to the runway and then make a right turn onto the runway heading. In fact, in order to taxi from J1 onto the runway, an aircraft must: taxi in a straight line; follow a curve to the right onto runway heading but still displaced to the right of the runway itself; turn left towards the runway; and then turn right again onto runway heading. The UK AIP states that there is no centreline lighting on Runway 03, and that the pavement width at the beginning of the runway is twice the normal runway width. It recognizes the potential for confusion and urges crews to ensure that they have lined up correctly. This information was not available to the crew on their aerodrome charts and both crew members believed that the runway had centreline lighting. Further, the light from those left-side runway edge lights covered in fog would have been scattered, making it harder for the crew to perceive them as a distinct line of lights. The situation is likely to have been made worse by the bright lights reflecting off the top of the fog layer, making the underlying runway lights even harder to see, or swamping them completely as shown in Figure 5. The CCTV images in Figure 5 show that peripheral lighting can interact with low fog layers to reduce the visibility of underlying aerodrome lighting. Current standards associated with apron lighting only address the minimum light levels required to make the areas safe and there are no standards relating to light spilling into other areas.
Human and environmental factors Five of the factors identified by the ATSB as being present in misaligned takeoffs were present in this accident:
1. It was dark.
2. It was potentially a confusing taxiway environment given that the aerodrome chart did not reflect the actual layout of the taxiways. Pilots had previously reported having difficulty when vacating the runway near the Runway 03 threshold because of a lack of taxiway lighting.
3. There was an additional paved area (the ORP) near the runway.
4. There was no runway centreline lighting and the runway edge lights before the displaced threshold were recessed.
5. There was reduced visibility.
It appeared that the information available to the crew caused them to develop an incorrect expectation of their route to the runway. Both crew members believed that the runway had centreline lighting and, when the first right turn almost lined the aircraft up with some lights, their incorrect expectation was reinforced and they believed that the aircraft was lined up correctly. Cues to the contrary, such as runway edge lights on the other side of the runway, or the fact that the first three lights ahead of the aircraft were red (indicating that they were edge lights before the displaced threshold), did not appear to have been strong enough to make the crew realize that they had lost situational awareness. Figure 8 indicates that the apparent intensity of the white left-side runway edge lights was significantly less than that of the right-side lights, when viewed from the position where the aircraft lined up. This, along with other visual issues relating to contrast and the fog, is a plausible explanation as to why they were not noticed by the crew. The aircraft began its takeoff roll from a location beyond the first red runway edge light and approximately 46 m short of the next light, as shown in Figure 1. Aircraft structure only obscures approximately the first 13 m of pavement ahead of pilots within a Gulfstream III aircraft and therefore these lights would not have been obscured by the aircraft. However, it is likely that the recessed nature of the red edge lights before the displaced threshold made them less compelling than the elevated white edge lights beyond, which would explain why their significance – that they could only have been runway edge lights – was not appreciated by the flight crew.

The crew's failure to recognize the activation of the stick shaker as a warning of an imminent stall, and the failure of the crew to execute the procedures for recovery from the onset of loss of control. Before the stick shaker warning activated, there was a confusion by the flight crew due to erroneous indications of relative speed increase and an overspeed warning. It is believed that the incorrect ASI readings was the consequence of an obstructed Pitot tube, maybe by mud and/or debris from a small insect that was introduced in the Pitot tube during the time the aircraft was on the ground. The aircraft was not flown for 20 days before the crash and was returned for service without a verification of the Pitot static system as recommended by Boeing.

Due to lack of evidences, the exact cause of the accident could not be determined. However, it is believed that the crew reported a low fuel warning.

The Canadian Aviation Safety Board was unable to determine the exact sequence of events which led to this accident. The Board believes, however, that the weight of evidence supports the conclusion that, shortly after lift-off, the aircraft experienced an increase in drag and reduction in lift which resulted in a stall at low altitude from which recovery was not possible. The most probable cause of the stall was determined to be ice contamination on the leading edge and upper surface of the wing. Other possible factors such as a loss of thrust from the number four engine and inappropriate take-off reference speeds may have compounded the effects of the contamination.

Improper IFR operation on part of the pilot who misjudged distance and altitude on final approach. The following factors were reported:
- High obstructions,
- Visual conditions,
- Dark night,
- No visual reference.

Investigations were unable to determine the exact cause of the accident.

Loss of control following an emergency of an undetermined nature.