TSB: Rotorcraft Prone To Lost Visual Reference Accidents

Loss-of-visual-reference accidents are more likely to involve helicopters than airplanes, according to a series of Transportation Safety Board of Canada (TSB) investigations. Reviewing 5,177 Canadian airplane and rotorcraft accidents recorded from 2000 to 2021, investigators found a total of 95 involving a loss of visual reference: 68 of 4,378 airplane accidents versus 27 of 799 helicopter accidents—a rate more than double that of airplanes.

The TSB has linked part of that disparity to Canadian regulations that do not require commercial helicopter operators to train pilots or equip aircraft to recover from inadvertent flight into instrument meteorological conditions (IIMC), relying instead on an avoid-at-all-costs strategy that investigators have called unrealistic.

Four recommendations were issued by the TSB to Transport Canada as a result of these investigations: require commercial helicopter operators to ensure pilots possess the skills to recover from IIMC; require implementation of technology to assist with IIMC avoidance and recovery; require single-pilot operators under Subpart 604 and Part VII of the Canadian Aviation Regulations (CARs) to develop SOPs based on corporate knowledge and industry best practices; and enhance requirements for helicopter operators conducting reduced-visibility operations in uncontrolled airspace.

Some Canadian operators have voluntarily gone beyond current regulatory minimums, the TSB found. It cited enhanced winter training, close monitoring of pilots for pressure to fly in marginal conditions, simulator-based IIMC recovery training, and dispatching aircraft equipped with radar altimeters and synthetic vision systems as measures already adopted by some operators.

The recommendations draw heavily on three recent TSB investigations into VFR helicopter missions that lost visual reference in flat light and whiteout conditions. All three resulted in accidents—one fatal.

On April 25, 2021, a Great Slave Helicopters 2018 Airbus Helicopters AS350 B2 departed a remote polar bear research camp on Russell Island, Nunavut, on a day VFR flight to Resolute Bay Airport, 87 nm to the northeast. On board were the pilot, an aircraft maintenance engineer, and a biologist. Approximately 45 minutes later, while crossing Griffith Island near its highest terrain, the helicopter struck snow-covered ground about 370 feet above sea level, shortly before reaching a ridgeline near the island’s high point, 12 nm from Resolute Bay. The crash and post-impact fire destroyed the helicopter, killing all three aboard. Investigators determined that the uniformly snow-covered, featureless terrain, an overcast sky, and nearby snowfall likely produced flat light and whiteout conditions, and that the wreckage orientation was consistent with the pilot attempting a 180-degree right turn after losing visual reference.

The pilot held a commercial helicopter license with approximately 4,050 total flight hours but only 16.4 hours of instrument flight time, just 3.5 of which had been logged in the five years before the accident. It was his first winter or spring deployment operating above the tree line from a remote camp.

Investigators found that no requirement existed for the pilot to be trained in IIMC recovery, nor for the aircraft to carry equipment that could assist with it. The helicopter did not have a radar altimeter, autopilot, or stability augmentation system. None of these are mandated for day VFR operations. The operator had adopted the avoidance-only philosophy. According to the report, management believed that IIMC training could make pilots overconfident about flying in deteriorating weather and considered VFR-only pilots unlikely to have the proficiency to hand-fly an instrument recovery.

A 2015 accident involving a predecessor company also involved an AS350 in flat light conditions near Deadhorse, Alaska, and prompted an internal review that found the original company’s manual had required flight instruments and night-VFR-style planning in whiteout conditions. Those requirements were no longer part of the operations manual by the time of the 2021 accident.

The advisory noted that standard operating procedures (SOPs), while required for multi-crew helicopter operations, remain optional for single-pilot operators under the CARs, despite being particularly useful when a pilot lacks experience in a given scenario. The report called reliance on an avoid-at-all-costs strategy unrealistic in regions like the Arctic, where flat light and whiteout conditions can develop quickly.

The TSB also pointed to a gap between helicopter and fixed-wing requirements for reduced-visibility operations in uncontrolled airspace. Rotorcraft may be authorized to operate in visibility as low as half a statute mile below 1,000 feet agl—half the one-statute-mile minimum required of fixed-wing aircraft. Unlike airplane operators under the same authorization, they need not carry an artificial horizon, directional gyro, or GPS, nor complete annual IFR training.

Citing the Royal Canadian Air Force, the report noted that one to two hours of annual instrument flight training, ideally supplemented with quarterly training, would give a VFR pilot a chance of surviving an IIMC encounter. From 1988 to 2022, the RCAF recorded 27 helicopter incidents attributed to loss of visual reference or IIMC; in 19 of those, IIMC and instrument flight training, procedures, or instrumentation were credited with contributing to a successful recovery.