On 13 October 2016, a Cessna 500 (C-GTNG) being operated by Norjet on a private passenger flight from Kelowna to Calgary disappeared from radar at night in undetermined flight conditions a few minutes after takeoff and its wreckage was subsequently located 4½ nm from the airport. All four occupants were confirmed killed as a result of the impact and/or the post-crash fire which followed.
An Investigation was carried out by the Canadian Transportation Safety Board (TSB). The aircraft was not equipped with a CVR or an FDR and neither was this a regulatory requirement. Recordings of relevant ATC radar and communications were available.
It was found that the pilot had accumulated a total of 3,912 flying hours which included 526 hours on type. He held an ATPL and had obtained the majority of his experience on a variety of single-engine aircraft as well as gaining multi-engine experience as a First Officer on the Cessna 560. He had been employed by the Operator 4½ years prior to the accident and on joining had completed his initial training to fly the Cessna 500 as part of a two pilot crew. He was subsequently trained for single pilot operations on various Cessna models including the Cessna 500 and a corresponding endorsement for such operations on that model was added to his licence in December 2013. However, it was found that he had logged 68 flights in the Norjet Cessna 500 as a single pilot prior to obtaining this endorsement. It was also found that he had completed only two night takeoffs and three night landings in the 6 months prior to the accident and therefore was in breach of the regulatory requirement that for passengers to be carried, a minimum of 5 night take offs and 5 night landings must have been completed in the previous 6 months.
It was established that the accident aircraft and pilot had arrived at Kelowna from Calgary at 0830 the same day and had then taken rest in a hotel until returning to the airport at approximately 1830 to operate the return flight which was due to depart three hours later. A Flight Plan was filed accordingly showing that the flight was expected to take about 45 minutes cruising at FL 250.
Once the three passengers had arrived and boarded, the aircraft had taxied for runway 34 and was cleared to enter and take off from its intersection with taxiway ‘D’ on a SID which required a straight ahead climb to 4,000 feet QNH with an automatic transfer to Vancouver Centre and a slight track adjustment direct to the Kelowna NDB at that point until radar vectors to the assigned route were given. Kelowna airport is located on a valley floor at an altitude of 1,421 feet and is surrounded by high terrain at elevations exceeding 7,000 feet.
After a normal take off, radar showed that when the aircraft was ½ nm beyond the departure end of the runway it was climbing at more than 4,000 fpm through 2,800 feet QNH at a climb angle of approximately 16°. Twenty seconds later, it was 1.2 nm beyond the runway passing 3,800 feet QNH and the rate of climb had reduced to about 1,600 fpm with a measured ground speed of 150 knots and its ground track was continuing to show a slow but continuing deviation to the right. The rate of climb was then further reduced quite quickly as its climb angle reduced to 2°. By the time it had climbed another thousand feet to 4,800 feet, it had deviated about 13° to the right of the intended track and its rate of climb had reached its maximum of approximately 6,000 fpm with a climb angle of about 22° at the expense of forward speed which produced a measured ground speed of about 145 knots. Passing 5,800 feet and still only 2.7 nm from the departure end of the runway, deviation right of intended track had reached 20°and the rate of climb was down to around 2,000 fpm with a climb angle of about 7°. At 6,000 feet, the first call to Vancouver Centre was made and acknowledged with a confirmation that the flight was radar-identified. The flight was then cleared to make a right turn en route to waypoint MENBO subject to achieving a safe altitude or being above 8,000 feet which was read back.
Just over half a minute after this readback and now above 8,000 feet, the right turn was commenced with climb continuing at approximately 3,000 fpm, a typical rate of climb for the aircraft type. The required track, which was 066°M, required a right turn of about 50° but this turn was not completed and at approximately 8,600 feet, the aircraft entered a steeply descending turn to the right which was assessed as “consistent with the characteristics of a spiral dive”. The calculated ground track of the aircraft is reproduced below.
An annotated reconstruction of the aircraft ground track. [Reproduced from the Official Report]
Thirteen seconds after the right turn had been commenced, ATC cleared the flight to climb to FL250 but the lack of a reply coupled with the disappearance of the radar return prompted the initiation of a search. About 2½ hours later, the wreckage with signs of a post crash fire having taken place was found in forested terrain at about 3,400 feet. The majority of the aircraft structure had been destroyed and there were no survivors. It was calculated that the aircraft had struck the ground at a high rate of descent in a 67° nose-down attitude on a 025°M heading with its high-energy impact resulting in an approximately 2 foot deep crater. Although both engines were severely damaged, the available evidence indicated that they had been producing significant thrust at impact.
The Investigation considered a number of potentially relevant factors:
- Although the Regulator had issued a Technical Approval for operation of the accident aircraft by a single pilot, no evidence was found that the also-necessary Operational Approval for single pilot operations had ever been assessed and granted and neither could it be determined whether such a request had ever been submitted by Norjet. It was also found that the Regulator had no formal process in place which covered the granting of such an approval for a C500.
- In 2007, the FAA had issued an AD which had required either the installation of upper and lower wing spar cap reinforcement angles or the commencement of indefinite checks for cracking of the spar cap stems every 600 hours or 600 landings whichever was reached first. No record of compliance with the AD in either respect could be found after its date of issue since when the accident aircraft had flown over 1,000 hours and made over 1,400 landings.
- Entries made in the Aircraft Technical Log two days prior to the accident indicated that the ‘HI’ setting for windscreen heating was inoperative with the consequence that flight into known icing conditions was prohibited. This defect was placarded in the flight deck.
- Errors were found in the current version of the aircraft weight and balance data sheet and that the effect of these in conjunction with the likely loading of the aircraft would have resulted in the aircraft being outside the permitted flight envelope by either 3.4 or 2.4 inches. However, it was concluded that the effect of this on the flight characteristics of the aircraft during takeoff would have been “negligible”.
- The aircraft was not equipped with a Stall Warning System but did have an angle-of-attack indicator which would have provided a visual cue of an impending stall. The only tactile warning of an imminent stall would have been aerodynamic buffeting of the wings which would have been evident as a shuddering or vibration of the airframe.
- The aircraft was fitted with an Autopilot but due to the post-crash fire, it was not possible to confirm whether it was fully serviceable prior to impact or whether it was in use.
- The Pilot was known to have taken a portable GPS unit and a laptop on board and it was determined that the former was probably positioned near the centre windshield. However, it was not possible to extract any data from it due to damage caused by impact forces and the post-crash fire.
- The weather conditions at the time the flight departed were likely to have meant IMC would be encountered during the initial climb with broken cloud at 2300 feet aal and a surface temperature of 7 °C meaning a potential freezing level of around 5000 feet. However, an analysis by Environment Canada indicated that “the weather conditions at Kelowna Airport at the time of the accident did not appear to be conducive to significant ice accretion”. No reference was made as to the relevance of this statement to conditions beyond the vicinity of the airport.
- Norjet was operating under the terms of a valid ‘Private Operator Registration Document (PORD)’ allowing it to engage in non-commercial business flight operations. As required by regulation, it had a SMS but it was not possible to establish whether it was effective at identifying and addressing safety risks because the person who administered it was the Pilot of the accident aircraft who was also the Company Operations Manager, Chief Pilot, Safety Officer and the person responsible for maintenance. At the time of the accident, regulatory oversight of operators such as Norjet was entirely reactive.
In analysing the available information about the circumstances which had led to the accident, the Investigation elected to focus on the following areas:
It was considered that loss of control in night IMC and the aircraft entering an unusual attitude such as a spiral dive was “a likely scenario” give that cognitive and/or physiological factors may have contributed to the loss of control by limiting the pilot’s ability to monitor and understand the flight instruments effectively. It was quite possible that the pilot had experienced some combination of spatial disorientation, high workload, and attentional narrowing associated with single-pilot operation of the aircraft was also considered. The lack of evidence that night and of instrument proficiency being maintained was noted. However, without recorded flight data, the factors that contributed to the aircraft deviating both laterally and vertically from the intended flight path during the climb and potentially to an eventual loss of control could not be conclusively established.
- Aircraft Weight & Balance
Although the flight was conducted outside the forward limit of the flight envelope, which created an increased wing loading and stall speed, it was considered unlikely that this situation had contributed to the accident.
- Aircraft Technical Anomalies
No evidence that a lack of airworthiness was likely to have contributed to the accident outcome was found. Whilst available radar data was considered to indicate that either the AP was in use and malfunctioning or that the aircraft was being flown manually, the malfunction case was considered unlikely. Also, since it was found that the ADI had been functioning at the time of impact, electrical power was available from at least one of the inverters. Finally, since there was no evidence of either an in-flight breakup or wing separation, it could be concluded that failure to comply with the requirements of the 2007 wing spar AD had not been relevant to the accident.
- Regulatory Oversight of Private Operators
The limited surveillance regime to which Norjet was subject had not detected some significant non compliances. It was noted that a previous TSB Investigation into a 2007 accident to a Bombardier Global 5000 had raised several concerns about oversight of business aircraft operators and led to a Safety Recommendation that a SMS be made a requirement for such operations. However, no action had been taken on this and the current Investigation had merely confirmed the likelihood that the current approach to private operator oversight is unlikely to support a timely rectification of safety deficiencies and unsafe practices.
- The Importance of On-Board Flight Recorders
In this Investigation, the lack of any flight data severely limited the opportunity to identify safety deficiencies that may have been significant. Lightweight FDRs are now available for installation in smaller aircraft and can record aircraft flight path data, voice communications and flight deck imagery and are increasingly being fitted voluntarily. The EUROCAE MOPS for such systems defines the minimum specifications for such systems but it is considered significant that Transport Canada currently has neither regulatory requirements nor specifications for them.
The formally stated Finding as to Cause was that “the aircraft departed controlled flight for reasons that could not be determined and collided with terrain”.
The formally stated Findings as to Risk were as follows:
- If flight data, voice, and video recordings are not available to an investigation, the identification and communication of safety deficiencies to advance transportation safety may be precluded.
- If night and instrument proficiency are not adequately maintained, a pilot may not be able to recognize an aircraft upset and respond appropriately, especially during high-workload situations, increasing the risk of loss-of-control accidents.
- If weight-and-balance documents are inaccurate, there is a risk that aircraft will be operated outside of the allowable centre-of-gravity specifications, which could affect flight stability and controllability.
- If Transport Canada does not effectively oversee private operators, this sector of aviation may be exposed to higher risks that could lead to an accident.
Three Other Findings were also identified:
- Federal Aviation Administration Airworthiness Directive (AD) 79-12-06 requires that the upper and lower spar caps be inspected for cracking every 600 hours or 600 landings, whichever comes first, unless Cessna Service Bulletin SB57-10 Rev 4 is carried out. A review of the technical records for the aircraft determined that the last record of compliance for AD 79-12-06 was dated 21 December 2007, and had taken place 1062 hours and 1405 landings earlier.
- The Investigation determined that there is no formal process in place at Transport Canada to assess and grant an operational approval for single-pilot operations on a Cessna Citation 500.
- Given that all components of the aircraft were accounted for at the wreckage site, the Investigation concluded that there was no in-flight breakup or separation of the wing.
Two Safety Concerns were formally highlighted by the Investigation:
- The Oversight of Private Operators which noted that although the Safety Recommendation made as a result of the TSB Investigation into a 2013 fatal accident to a Sikorsky S76A calling for regular assessments of SMS effectiveness was directed at commercial operators, the same concern applies to private operators.
- The provision of lightweight FDR for Private Operators which noted the lack of progress in addressing a 2013 TSB Safety Recommendation advocating such recorders be mandated for commercial operators of smaller aircraft given the likelihood that the extension of such a requirement to private business operators of such aircraft would be similarly beneficial.
One Safety Recommendation was made in respect of the second Safety Concern identified above as follows:
- that the Canadian Department of Transport require the mandatory installation of lightweight flight recording systems by commercial operators and private operators not currently required to carry these systems. [Recommendation A18-01]
The Final Report of the Investigation was authorised for release on 28 February 2018 and it was officially released on 26 April 2018.