Fatal Mid-Air Collision Near Sioux Lookout, Ontario Between a Bearskin Airlines, Fairchild Metro 23, C-GYYB and Air Sandy, Piper PA-31 Navajo, C-GYPZ, 01 May 1995
Report No. A95H0008
(For release 18 April 1996)
(Hull, Quebec) - The Transportation Safety Board (TSB) has completed the report on its investigation into the fatal mid-air collision, 01 May 1995, near Sioux Lookout, Ontario, involving a Bearskin Airlines Fairchild Metro 23 and an Air Sandy Piper Navajo. The report contains four safety recommendations concerning separation procedures in uncontrolled airspace, collision avoidance procedures, and the requirements for commercial passenger aircraft to be equipped with collision avoidance systems.
The Air Sandy flight 3101, with one pilot and four passengers on board, had just departed Sioux Lookout for Red Lake, Ontario. Bearskin Airlines flight 362, with a crew of two and a passenger on board, was inbound to Sioux Lookout on a flight from Red Lake. The two aircraft collided at 4,500 feet above sea level, at approximately 1328 CDT, 12 nautical miles northwest of Sioux Lookout. All eight persons on board the two aircraft died in the accident.
Both aircraft were being flown in visual meteorological conditions under visual flight rules (VFR) and were closing at a speed in excess of 400 knots just prior to the collision. The crew on another aircraft at 4,000 feet, who saw the flash of the collision, reported that the visibility was unlimited beneath a solid overcast at approximately 6,500 feet, and that there was no direct sunlight breaking through the cloud.
The Board determined that neither flight crew saw the other aircraft in time to avoid the collision. Contributing to the occurrence were the inherent limitations of the see-and-avoid concept, which preclude the effective separation of aircraft with high closure rates; the fact that neither crew was directly alerted to the presence of the other; and an apparent lack of pilot understanding of the optimal avoidance manoeuvre techniques.
Global positioning system (GPS) receivers have been approved for use under VFR and as a backup for IFR flights. GPS is an inexpensive and accurate navigation system. Ironically, this accuracy increases the potential risk of collision for aircraft on the same GPS track. Given the increasing usage of GPS, and the increased potential for mid-air collision associated with its use, the Board has recommended that:
The Department of Transport expedite the development and implementation of safe separation procedures for the use of GPS in navigation. [A96-04]
Where procedures to separate aircraft fail, pilots have to rely on the see-and-avoid method to avoid a mid-air collision. This method, however, becomes less effective as aircraft speeds increase. In this accident, it is estimated that the closing speed of the two aircraft was 410 knots. According to research, at this speed the probability of one crew seeing the other aircraft on the collision course and taking evasive action is about 20%. If the closing speed is reduced to 300 knots, the probability of taking effective evasive action doubles. In light of the increased probability of detecting conflicting traffic at reduced airspeeds, the Board has recommended that:
The Department of Transport ensure that aircraft are flown at reduced airspeeds, consistent with safe manoeuvring, in the vicinity of aerodromes where separation relies primarily on the see-and-avoid concept. [A96-05]
Even if aircraft are flown at reduced airspeeds, pilots must be able to recognize a collision threat and take appropriate action if a collision is to be avoided. Transport Canada's Flight Instructor's Guide advocates the use of a steep turn to avoid collisions; however, this manoeuvre may actually increase the probability of impact when the aircraft are in close proximity. Since inappropriate responses to a risk of collision situation may increase the risk of a mid-air collision, the Board has recommended that:
The Department of Transport take both long and short-term action to increase the ability of pilots to recognize in-flight collision geometry and optimize avoidance manoeuvring. [A96-06]
The see-and-avoid method of traffic separation can be more effective if pilots are alerted to the existence and relative location of conflicting traffic. There are traffic collision avoidance systems (TCAS) that can provide such traffic alerts. In view of the capabilities of TCAS, and the increasing risk of collision due to improved navigational accuracy, increased aircraft speeds, and mixed VFR/IFR traffic at uncontrolled airports such as Sioux Lookout, the Board has recommended that:
The Department of Transport conduct an analysis of the benefits of requiring commercial passenger-carrying aircraft to be equipped with TCAS versus the risks associated with operating aircraft without TCAS. [A96-07]
The Transportation Safety Board of Canada is an independent agency operating under its own Act of Parliament. Its sole aim is the advancement of transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability.
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The TSB is an independent agency that investigates marine, pipeline, railway and aviation transportation occurrences. Its sole aim is the advancement of transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability.
For more information, contact:
Transportation Safety Board of Canada
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