Understanding Night VFR and the CFIT Risk
On October 30, 1997, a Piper PA-34-200T Seneca departed Fort McMurray, Alberta, on a 62-NM charter flight to La Loche, Saskatchewan, with one pilot and five passengers on board. The aircraft departed at 17:50, and was expected back in Fort McMurray at 19:30. The pilot filed a visual flight rules (VFR) flight plan, and when the aircraft did not return, the Fort McMurray flight service station (FSS) operator initiated a radio search that was not successful. After the FSS contacted the operator, an airborne search party organized by the operator departed from Fort McMurray, but could not find the aircraft. Another search was organized using military resources and the wreckage was located on the afternoon of the following day. Three surviving passengers were taken by military aircraft to La Loche and then to Fort McMurray, with serious injuries. The aircraft was destroyed by impact forces and a post-crash fire. This summary is based on Transportation Safety Board (TSB) Final Report A97C0215.
The report states that the passengers were anxious to complete the trip in order to facilitate an appointment the following day. The pilot called the FSS to check the weather at Fort McMurray and Buffalo Narrows, and filed a visual flight rules (VFR) flight plan. The pilot consulted another company pilot who had returned from a flight to La Loche at 15:00, and was advised that the cloud ceiling was about 500 ft. above ground level (AGL) at La Loche and as low as 200 ft. AGL in some areas along the west shore of La Loche lake. On his last contact with the Fort McMurray FSS after departure, the pilot advised that he had departed the control zone to the east. A passenger reported that the aircraft was flying below the cloud at a low altitude shortly before the crash.
The wreckage was found at an elevation of about 1540 ft., and had struck the tops of poplar trees at an elevation of about 1600 ft. in a shallow descent, with a right bank angle of 10 to 15 degrees. The aircraft was on course, with the landing gear and flaps retracted, when it struck the trees. The shallow angle of the aircraft’s impact with terrain, and the speed of the aircraft at impact are consistent with controlled flight into terrain (CFIT).
An examination of the wreckage indicated that both engines were developing power at the time of impact, and no evidence of a pre-crash malfunction was found. The emergency locator transmitter (ELT) was destroyed in the crash and did not activate. The pilot was one of the more experienced company pilots. He had reportedly completed a pilot decision making (PDM) course, and was described as proficient and safety-conscious.
The weather at Fort McMurray at 18:00 included a ragged overcast cloud ceiling at 1000 ft. AGL. The terminal area forecast for Fort McMurray from 16:00 to 22:00 was as follows: winds 120 degrees at 8 kt., visibility greater than 6 SM, and an overcast ceiling at 1000 ft. AGL, with a temporary fluctuation of the visibility down to 4 SM and a temporary fluctuation of the ceiling down to 500 ft. AGL. The area forecast included the possibility of light to moderate icing in cloud.
La Loche is not served by an official weather reporting agency. However, pilots reported that at the time of the accident, La Loche was experiencing overcast cloud ceilings of about 500 ft. AGL and that ceilings were lower over the higher ground west of La Loche, in the direction of Fort McMurray. Although the pilot was qualified to complete the flight under instrument flight rules (IFR), the aircraft was not equipped for IFR flight under the prevailing conditions.
At the time of departure, the cloud ceiling met the requirements for night VFR flight in the Fort McMurray area. As the flight progressed toward La Loche, the cloud ceiling decreased below the minimum required for commercial air operations. Flight below the cloud left the pilot with reduced terrain clearance and increased the requirement for effective manoeuvring to avoid collision with terrain.
The lighting conditions on departure were likely sufficient to allow the pilot to maintain a visual reference to the ground. As the flight progressed, however, the available lighting and ground reference progressively decreased. The overcast sky, the decreasing sky illumination, and the dark colour of the forested area along the route and in the area of the accident yielded little light with which the pilot could manoeuver and navigate with reference to the ground.
The aircraft was not equipped with propeller or airframe de-ice or anti-ice devices. Such devices are required by regulation for an aircraft operating in known icing conditions. Section 602.115 of the Canadian Aviation Regulations (CARs) provides that night VFR flight requires a visibility of three miles; no minimum altitude is specified. However, section 703.27 of the CARs stipulates that an operator of an air transport service flying at night must maintain an obstacle clearance height of 1000 ft. AGL. Commercial night VFR flight must be conducted on a route, and air operators are required to maintain a record of company routes. The accident aircraft was reportedly not equipped with a route manual, nor was a route manual found at the operator’s base after the accident. Other pilots employed by the operator were not familiar with the obstacle clearance requirement found in the CARs, nor with the requirements of a route for night VFR flight.
Although the operator’s Flight Operations Manual (FOM) has detailed information on day VFR flight standards, the section on night VFR contains little guidance. The requirement for the minimum obstacle clearance height is not contained in the company operations exam, and the level of pilot awareness of the requirement within the company indicates that the pilots were not receiving the information from other sources.
Although it was not established whether the pilot was subject to pressures from the passengers, customer and self-induced pressures were encountered frequently by company pilots in their dealings with other customers. As well, the occurrence aircraft was already loaded with the passengers’ baggage prior to the pilot’s return from his previous flight, and a company pilot had recently successfully completed a flight from La Loche. It is not known to what extent the pilot’s decision to depart was influenced by one or more of these factors.
Among its findings, the TSB determined that the weather at departure from Fort McMurray was within allowable limits for night VFR flight; however, as the flight progressed toward La Loche, the cloud ceiling decreased below allowable limits for a commercial air operator, and the available lighting and ground reference available en route and at the time of the accident decreased markedly from that prevailing on departure.
The TSB also determined that the operator’s FOM contained little guidance to pilots on the subject of night VFR operations, and that company pilots were subject to customer and self-induced pressures from time to time to complete flights in adverse conditions.
The TSB concluded that the pilot continued flight into adverse weather and lighting conditions that did not enable him to avoid collision with terrain. Contributing factors to this occurrence were the aircraft’s unserviceability for single pilot IFR flight and the lack of guidance to company pilots as to weather limits for night VFR flight.
As a result of this accident, the TSB sent two aviation safety advisories to Transport Canada (TC) on night VFR requirements and night VFR routes in uncontrolled airspace, suggesting that (1) TC may wish to consider disseminating applicable information to operators; and (2) TC ensure this information is included in company operations manuals.
In addition to publishing this article, TC has also issued a Commercial and Business Aviation Advisory Circular to bring attention to the situation and ensure that company operations manuals contain all required information.