On 13 April 2015, a Swearingen SA226 Metro II (C-GSKC) being operated by Carson Air on a scheduled domestic cargo flight from Vancouver to Prince George as CA66 disappeared from radar in day IMC after suddenly entering an unexplained and very steep descent about 6 minutes after takeoff without any communication from the pilots. It was later found to have impacted terrain at high speed after structural disintegration had begun before impact and a post-crash fire completed the destruction of the aircraft. Both pilots were killed. .
An Investigation was carried out by the Canadian TSB. The aircraft was not equipped with a CVR or an FDR and neither was a regulatory requirement. Having expressed concern after conducting previous investigations at the difficulties which the lack of these devices presents and having made a corresponding Safety Recommendation to the Canadian Regulator in 2013, it was noted that after 5 years it was still “unclear when or how the safety deficiency identified […] will be addressed”.
Note: Subsequent to the publication of this Report, the TSB completed their investigation into a 2016 fatal accident to a Cessna 500 during which they were unable to determine why it crashed for similar reasons, namely the absence of any crash-protected flight recorder. The lack of any corresponding requirement for them in some classes of both commercially and privately operated aircraft led to Safety Recommendation (A18-01) that they should be required being made.
It was found that both pilots held CPLs. The 34 year-old Captain, who the available evidence indicated had been PF for the accident flight, had a total of 2,885 flying hours which included 1,890 hours on type. He had been employed by Carson Air as a First Officer two years prior to the accident and in December 2014 had been promoted to Captain, although with less than a week in this role, it was found that “another company pilot reported an incident in which he had had to take control from the Captain” and a performance review was instigated. This had included a day of operational flying with Check/Training Captain and had been closed off after an assessment that he was “effective, competent, or highly effective in most evaluated categories (with) no areas of concern with his performance identified”. The recently employed First Officer had completed his type conversion training three weeks prior to the accident and his 1,430 total flying hours included just 57 hours on type.
It was noted that both the Captain and First Officer were observed on report for their duty at Vancouver, their operating base, to have respectively “appeared to be in a positive state of mind” and “be in good spirits”. In particular, no abnormal behaviour by the Captain was observed by anyone with whom he had contact. After a weekend off, the crew’s Monday morning duty involved operating a cargo flight from Vancouver to Fort St. John, with stops at Prince George and Dawson Creek, a total distance of approximately 360 nm. The First Officer had arrived about 15 minutes prior to the Captain. After the crew had boarded the aircraft, carried out pre-flight checks and loaded the cargo themselves, the engines were started half an hour after the Captain had arrived at crew report and a little over 15 minutes later, ATC observed a normal takeoff.
After contacting Vancouver Terminal Departure Control, the flight was cleared to climb to 9,000 feet QNH on a northerly heading. A frequency change to Vancouver ACC followed and as the aircraft climbed through 7,500 feet QNH, the flight was re-cleared to FL 200, the flight planned cruise altitude. The acknowledgment of this was the aircraft’s last radio transmission and 1 minute and 20 seconds later (and approximately 7 minutes after takeoff) whilst passing 8,700 feet QNH on a radar heading of 350°, the aircraft returns on the ACC secondary surveillance radar displays disappeared. The flight’s radar track showed a normal climb rate of 1,500 fpm with the groundspeed increasing gradually to a maximum of approximately 185 knots and a maximum transmitted altitude of 8,700 feet QNH.
The next return then showed an abrupt change to a steep descent and was followed by two more, one at 7,600 feet and the last one at 5,000 feet without any change in the direction of flight. During the initial part of this descent, the aircraft pitched down at about 6° per second with its vertical acceleration reaching -0.6g. The descent to 5,000 feet altitude was estimated to have taken 10 to 14 seconds at a rate of descent exceeding 30,000 fpm with aerodynamic forces causing structural disintegration of the aircraft. The first impact occurred at approximately 3,400 feet amsl. The aircraft was destroyed by the impact and the wreckage showed extensive damage caused by a fuel-fed fire that had eventually self-extinguished. Examination of the wreckage confirmed that there was no in-flight fire. Despite poor weather conditions, the accident site was found later the same day and it was confirmed that both pilots had been killed. The aircraft’s 406 MHz ELT was activated but its damaged antenna meant that no signal was received by the COSPAS-SARSAT system.
Based on available meteorological information, it was concluded that the flight would have been very likely to have been climbing in cloud and in icing conditions once above about 5,000 feet QNH. Pilot reports from a number of aircraft which transited the area of the accident aircraft’s last radar return described experiencing “smooth flying conditions with light turbulence […] light rime icing conditions in cloud (and) cloud tops at 14,000 feet”. Satellite coverage at the time showed no significant cumulus or other convective cloud in the area and sensors had not detected any lightning discharges in the area. The aircraft was equipped with manually selected pitot tube and angle of attack vane electrical heating with switching for both only accessible to the Captain and in a position outside the First Officer’s normal field of view. However, the warning light and annunciator panel on the central combing readily visible to both pilots included a green light which illuminated when both these independently selectable heaters were on but there was no alert if only one or the other heater was on apart from the absence of the green light.
A number of other potentially relevant factors or context were considered:
- The loading of the aircraft was considered and although it was within the permitted flight envelope, it was determined that at 180 KTAS, the prevailing centre of gravity would have required that the horizontal stabilizer trim was in a position close to the nose-down limit.
- It was determined that both pilots were wearing their shoulder harnesses and noted that this would have had the effect of preventing either pilot from exerting a significant forward force on their control column had they fallen on it while incapacitated or unconscious. It was concluded that such a force as would have been exerted in such circumstances would have been quite capable of being overcome by the other pilot using his own control column.
- The accident aircraft was not equipped with an autopilot, nor was there any regulatory requirement for this.
- No evidence was found that could suggest that the performance of either pilot was affected by fatigue.
- Carson Air was not required to provide CRM training or have an SMS. It did voluntarily provide CRM training for new hire pilots and had voluntarily implemented an SMS but neither had been evaluated by the regulator nor was this required.
- Operational Control of flights at Carson Air involved “authority over the formulation, execution and amendment of an operational flight plan being delegated by the company Operations Manager to the pilot-in-command” with the effect that “flights are self-dispatched and released by each flight’s Captain”.
The Pilots’ Medical and Pathological Information
Post-mortem examinations and toxicological screening were conducted on both pilots. These did not yield anything relevant in respect of the First Officer but did do so in respect of the Captain.
His post-mortem toxicological screening revealed the presence of ethyl alcohol in his system at a Blood Alcohol Content (BAC) of 0.24%, a level which, in conjunction with other measurements, indicated that he had “likely consumed alcohol over a period of several hours, until shortly before the flight’s departure”. The autopsy found signs of “severe coronary artery atherosclerosis” and evidence of both steatosis and hepatitis in his liver. It was considered that the collective finding of these conditions in a person of the Captain’s age “suggested excessive alcohol consumption over a significant period”. However, none of his routine periodic medical examinations - the most recent was 10 months prior to the accident - had identified any issues related to alcohol abuse.
Enquiries then found that “a number of company employees had suspicions, and some had voiced concerns with colleagues, that the Captain had a drinking problem”. On at least one occasion, it was stated that a Carson Air employee had told a supervisor that he had smelled alcohol on the captain’s breath but since the supervisor concerned did not also detect such a smell, the matter was not pursued further and instead, it was decided to “monitor the situation”.
The Investigation noted that physical dependence on alcohol involves functional tolerance to its effects which results in chronic heavy drinkers often showing few obvious signs of intoxication, even at a much higher BAC than the 0.24% found. However, the effects on performance at the 0.24% BAC detected would still include, to a greater or lesser degree in an individual case “emotional instability, loss of critical judgment, impairment of memory and comprehension, decreased sensory response, and mild lack of muscular coordination”. In respect of the specific task of piloting, it was noted that “alcohol impairs almost all forms of cognitive functioning, including attention, information processing, decision making, and reasoning” and also that “because alcohol impairs new-information processing, problem solving, and abstract thinking, performance suffers most when an unexpected or unanticipated event occurs”. The potential for alcohol to increase the risk of spatial disorientation in pilots was particularly noted.
It was noted that a 2006 Australian review aimed at informing the possible introduction of drug and alcohol testing in the aviation industry had “estimated that alcohol abuse and dependence affects approximately 5%-8% of all pilots, similar to the proportions in other professional occupations such as law and medicine”.
Finally, it was also noted that whilst there was no supporting evidence to indicate that the Captain may have been suicidal, there was also no evidence that could readily discount this possibility.
The formally stated Findings as to Causes and Contributing Factors were as follows:
- For unknown reasons, the aircraft descended in the direction of flight at high speed until it exceeded its structural limits, leading to an in-flight breakup.
- Based on the Captain’s blood alcohol content, alcohol intoxication almost certainly played a role in the events leading up to the accident.
The formally stated Findings as to Risk were as follows:
- If cockpit or data recordings are not available to an investigation, the identification and communication of safety deficiencies to advance transportation safety may be precluded.
- If Canadian Aviation Regulations Subpart 703 operators are not required to have a Transport Canada–approved safety management system, which is assessed on a regular basis, there is a risk that those companies will not have the necessary processes in place to manage safety effectively.
- If safety issues, such as concerns related to drug or alcohol abuse, are not reported formally through a company’s safety reporting system, there is a risk that hazards will not be managed effectively.
- Transport Canada’s Handbook for Civil Aviation Medical Examiners (TP 13312) does not address the complete range of conditions that may be affected by drug or alcohol dependence. As a result, there is an increased risk that undisclosed cases of drug or alcohol dependence in commercial aviation will go undetected, placing the travelling public at risk.
- If there is no regulated drug and alcohol testing requirement in place to reduce the risk of impairment of persons while engaged in safety-sensitive functions, employees may undertake these duties while impaired, posing a risk to public safety.
Safety Action' taken by Carson Air as a result of the accident and known to the Investigation included:
- the introduction of a Company drug and alcohol awareness campaign and implementation of policies for dealing with suspected substance abuse.
- the amendment of Company Standard Operating Procedures (SOPs) to increase the period during which all company employees must abstain from alcohol from the regulatory minimum of 8 hours to 12 hours.
- the implementation of an improved Emergency Response Plan.
- the introduction of an anonymous online reporting process to encourage timely reporting of safety concerns.
One Safety Recommendation was made as follows:
- that the Canadian Department of Transport in collaboration with the Canadian aviation industry and employee representatives, develop and implement requirements for a comprehensive substance abuse program, including drug and alcohol testing, to reduce the risk of impairment of persons while engaged in safety-sensitive functions. These requirements should consider and balance the need to incorporate human rights principles in the Canadian Human Rights Act with the responsibility to protect public safety. [Recommendation A17-02]
The Final Report of the Investigation was authorised for release on 13 September 2017 and it was officially released on 2 November 2017. .