Lack of oxygen likely caused fatal plane crash near Calgary, TSB report says

The Transportation Safety Board of Canada says lack of oxygen likely played a role in a plane crash southwest of Calgarythat killed two people a year ago.

The board says in a report that hypoxia, or in-flight oxygen deprivation, caused the pilot to lose control before crashing into Mount Rae, in Kananaskis Country, on Aug. 1, 2018.

It says the pilot was travelling in a Piper PA-31 Navajo with a survey technician and they were headed to the Springbank Airport near Calgary.

The TSB says although a portable oxygen system was available on the plane, the pilot was not continuously using it while the aircraft was4,000 metres above sea level, which is required by regulation.

• 2 dead after plane crash in Kananaskis

It says hypoxia slows down body functions, but its onset can be slow and gradual, so it's likely the pilot did not recognize the symptoms.

The board also found that flight crews do not undergo practical hypoxia training and there is a risk they will not recognize early symptoms in higher altitudes.