TSB featured article

This article was published in Wings Magazine, September/October 2009 Volume 50 Issue 5

Air Accident Investigation

The TSB's evolving commitment to worldwide safety

By Chris Krepski, Transportation Safety Board of Canada

Civil aviation in Canada has been regulated since 1923. It was first the responsibility of the Department of National Defence until it was transferred to the Department of Transport when the department was formed in 1936.

In 1960, the Aircraft Accident Investigation Branch was established as part of the Department of Transport. The responsibility for investigating air accidents remained with the regulator for another 24 years. However the move towards significant changes in civil aviation regulation began in 1979 with the Commission of Inquiry on Aviation Safety (the Dubin Commission).

One of the Dubin Commission's key recommendations was the establishment of an independent accident investigation board, modeled on the National Transportation Safety Board (NTSB) in the United States. Thus in 1984, the Canadian Aviation Safety Board (CASB) was formed to investigate all aviation accidents, incidents and situations it felt were potentially hazardous. The CASB would be composed of at least three Board members and would report to Parliament through a minister other than the Minister of Transport. It would make its recommendations about increasing aviation safety public as part of its accident investigation reports. While the CASB's recommendations were not binding, the Department of Transport was to announce its response publicly within 90 days. A voluntary incident reporting system, whereby pilots or air traffic controllers could report incidents without being subject to prosecution, was also established.

With the enactment of the Canadian Transportation Accident Investigation and Safety Board Act in April 1990, the Transportation Safety Board of Canada (TSB) as we know it today was formed. In addition to investigating aviation occurrences, the TSB also took responsibility for investigating railway, marine and pipeline occurrences -activities formerly conducted by the regulators. The TSB is truly independent in that it reports to Parliament through the President of the Queen's Privy Council for Canada and is separate from other federal departments and agencies. Across all the modes it investigates, the Board's only goal is to advance transportation safety by investigating occurrences, identifying and making public safety deficiencies, and where necessary, issuing formal recommendations to address systemic safety issues.

Significant investigations

Since its inception, the TSB has conducted over 1,800 investigations into more than 33,000 reported air occurrences. Some of its major air investigations include:

  • The September 2, 1998 in-flight fire and collision into water of Swissair Flight 111 near Peggy's Cove, NS.
  • The October 14, 2004 crash at the end of the runway of a MK Airlines Boeing 747 cargo flight in Halifax, Nova Scotia.
  • The March 6, 2005 loss of rudder in flight of Air Transat Flight 961 near Miami, Florida.
  • The August 2, 2005 runway overrun and fire of Air France Flight 358 at Lester B. Pearson International Airport in Toronto, Ontario.
  • Two Cessna Caravan icing-related accidents: the January 2, 2004 crash of Georgian Air Express Flight 126 near Pelee Island, Ontario and the October 6, 2005 accident involving a Morningstar Air Express cargo flight in Winnipeg, Manitoba.
  • The July 2, 2007 tail rotor drive shaft fracture of Black Tusk Helicopters, a Bell 214B1, in Ramsay Arm, British Columbia.
  • Two accidents involving commercial hot-air balloon operations: the August 11, 2007 fire aboard a balloon in Winnipeg, Manitoba and the fatal August 24, 2007 fire and crash of a balloon in Surrey, British Columbia.
  • The March 12, 2009 fatal collision with water of Cougar Flight 491, a Sikorsky S-92A helicopter, off the coast of St. John's, Newfoundland and Labrador.

The work of Canadian investigators on these investigations and others has helped to establish the TSB as one of the world's most credible and thorough accident investigation agencies.

Advancing the art and science of accident investigation

TSB investigators have always been and continue to be innovative in developing and using new techniques to gather and analyze information from accident sites.

Our investigations are conducted using the Integrated Safety Investigation Methodology (ISIM). It is a set of tools and techniques that allows investigators to collect and organize pertinent accident information, identify the sequence of events leading to the accident and analyze the available information to identify safety deficiencies. Three major elements: the flight crew, the aircraft and the environment they operated in, are analyzed. Through a process of elimination, the investigation focuses on the safety deficiencies that contributed to the occurrence. From there, staff can develop compelling arguments for safety actions and communicate the findings, safety deficiencies and safety actions taken and required in final reports and other safety communications. To compliment ISIM, the TSB developed the Transportation Investigation Information Management System (TIIMS) for gathering and managing all of the information gathered and analyzed during investigations. Because its structure is based on ISIM, using TIIMS for information storage and retrieval is more intuitive and efficient.

A time-honoured investigative technique is laboratory wreckage analysis. Parts of interest such as engines, instrumentation and flight control surfaces are routinely disassembled and closely examined by TSB Engineering Laboratory staff. We can find 'witness marks' on instrument dials, which offer clues as to the airspeed, engine power and fuel remaining at impact. By examining light bulbs from cockpit annunciator panels, we can tell which were illuminated at the time of impact when we find the bulb filaments are expanded, thus providing an indication of what cockpit warnings the crew was receiving.

In 1986, Engineering Laboratory staff at CASB began to develop the Recorder Analysis and Playback Software (RAPS). At that time, no such tool was commercially available. As the capabilities of RAPS increased, other accident investigation agencies approached the CASB and later the TSB to use the software. By the year 2000, there were 14 international users. In 2001, the TSB decided to commercialize RAPS. Today, we are proud to know there are many different users of this software, from accident investigators to aircraft manufacturers and operators, who use it to improve product and operational safety. It is also a useful tool for developing flight path animations, which provide investigators, interested parties and the general public a visual depiction of an accident.

As more and more digital technology makes its way into aircraft, TSB investigators have been successful on a number of occasions in recovering data from these systems. Valuable information has been recovered from non-volatile memory found in GPS units, full-authority digital engine controls, pilot flight and multi-function displays to name a few. Even photos from digital and film cameras found at accident sites have been recovered for investigative purposes. This data is useful in gaining a better understanding of the sequence of events leading to an accident and can supplement flight recorder data or fill in the blanks when it is unavailable.

Towards safer skies

When significant safety deficiencies are uncovered during investigations, the TSB advises manufacturers and regulators as soon as possible so remedial action can be taken. Often changes are made before an investigation is completed, but if not, safety communications and Board recommendations are issued. Generally, regulators and industry respond positively to our communications and numerous improvements to aviation safety in Canada and worldwide have resulted.

Some early findings as part of the TSB's ongoing investigation into the March 12, 2009 crash of the Cougar Helicopters Sikorsky S-92 in Newfoundland led to prompt safety action by the United States Federal Aviation Administration (FAA) and Sikorsky. The FAA issued an emergency airworthiness directive (AD) to replace the main gearbox oil filter bowl mounting studs when it was discovered that two of the three studs on the accident helicopter failed. Sikorsky also revised the S-92 rotorcraft flight manual to indicate the need to land immediately when there is low main gearbox oil pressure indication.

In 2005, Transport Canada revised its standard passenger and carry-on baggage weights to more accurately reflect the increased weight of today's passengers and baggage. These regulations came as a result of a TSB recommendation issued during the Georgian Air Express investigation, which found that the aircraft took off overweight in icing conditions. As a result, pilots now have more accurate guidelines when doing their weight-and-balance calculations before takeoff.

Numerous changes to Cessna Caravan operations in icing were implemented following the Georgian Air Express and Morningstar Air Express accidents. More stringent pre-flight inspections for snow/ice contaminations are now required. Another airworthiness directive was issued by the FAA to require pilots to exit moderate or greater icing conditions and maintain higher airspeeds when icing is encountered. The manufacturer has also changed the icing protection systems aboard the aircraft. These changes should go a long way in making Cessna Caravan operations in ice safer.

During the Swissair investigation, TSB investigators found that both the CVR and the FRD on Swissair 111 ceased to function some five and a half minutes before impact. Consequently, the lack of quality data severely hampered our efforts to validate some of the primary safety deficiencies. This is why the Board made eight flight recorder-related recommendations, including increasing recording time and providing independent power sources. While progress is still required in some areas, the FAA issued new regulations requiring that by 2012, flight recorders have 2-hour recording capacities, independent power supplies capable of providing 10 minutes of power and ensuring that a single electrical failure does not result in the disabling of both flight recorders.

Early in our investigation of the in-flight rudder separation on an Airbus A310 in March 2005, we discovered that the inspection program for composite rudders at the time was not adequate for providing timely defect detection. As a result, Airbus issued an All-Operators Telex calling for an inspection of all aircraft equipped with similar composite rudders. In all, 408 Airbus widebody aircraft were inspected. Following these inspections, the TSB recommended to Transport Canada, the European Aviation Safety Agency and the industry to come up with improved inspection programs for composite components. TC, EASA, Airbus and the FAA agreed and have implemented improved inspection programs to prevent similar accidents.

In August 1999, a Beech 1900D landed short of the runway while making an instrument approach into Sept-Iles, Quebec at night in low visibility conditions. At the time of the occurrence, there had been 24 similar accidents that resulted in 34 fatalities and serious injuries. Regulations at the time only prohibited approaches into airports based on runway visual range (RVR) reports. Therefore, as part of the investigation, the Board recommended more stringent regulations to ban approaches in low-visibility conditions. Transport Canada responded favourably with new approach ban regulations that included minima based on human runway visibility reports in addition to RVR reports in December 2006.

Reaching out in Canada and internationally

The TSB actively co-operates with manufacturers, operators, regulators and accident investigation authorities worldwide. It is absolutely essential to maintain close contact with these parties to advance safety, given the global nature of the industry.

It is also vital to aviation safety to maintain open lines of communication with operators on the safety deficiencies they encounter. Through the occurrence reporting requirements and confidential SECURITAS reports, the TSB gathers information on occurrences, identifies safety risks and tells operators and the regulators what we learned so that these can be corrected. Sharing knowledge of hazards increases safety for everyone in the industry.

The TSB maintains close contact with Transport Canada to ensure the regulator is notified as soon as possible of safety deficiencies we identify. Since so many aircraft in Canada are manufactured in the United States, we also maintain a close relationship with the FAA when airworthiness-related deficiencies arise.

Each year, Board members speak at various Canadian and international conferences attended by decision-makers in the aviation industry. For example, during the 10th Anniversary of the Swissair Flight 111 accident in 2008, Board members addressed various audiences in Canada, the United States, the United Kingdom and Russia. These presentations aimed to recognize progress made in advancing safety since the investigation and to highlight the work that remains. The TSB is also a member of the International Transportation Safety Association (ITSA), an organization made up of 13 national accident investigation authorities. ITSA members meet annually with the goal of learning from each others' experiences, discussing safety deficiencies that are being identified and to share expertise.

TSB investigators have participated in the International Society of Air Safety Investigators' (ISASI) Reachout Program. This important program seeks to provide low-cost training to government and industry officials on air accident investigation and for ISASI members to share knowledge and expertise in aviation safety.

The TSB represents Canada at ICAO on matters related to Annex 13 of the Chicago Convention, which deals with aviation occurrence investigations. Annex 13 outlines the rights and responsibilities of states regarding aviation accidents, and the standards and recommended practices for data gathering, analysis, final report production and accident prevention measures. The TSB participates at the Accident Investigation Group meetings to discuss proposed changes and provide input. Additionally, a TSB investigator is part of the team that audits the compliance of other states with Annex 13.

Conclusion

Air accident investigation in Canada has evolved along with changes in the aviation industry, technology, accident causation theories and investigation goals. Today, the TSB exists as an independent investigation authority with the sole goal of advancing transportation safety. Thanks to the professionalism and dedication of its staff, the TSB has made significant contributions to accident investigation techniques and methodologies over the years. Through its close contacts with regulators, manufacturers and other investigative authorities, findings from TSB investigations have led to numerous improvements to operational practices, equipment design and regulations throughout all sectors of the aviation industry.