Brief Summary
This video tells the story of Pacific Western Airlines (PWA) Flight 314, a Boeing 737-200 that crashed in Cranbrook, British Columbia, in 1978. The accident was caused by a chain of events, including an incorrect estimated time of arrival (ETA) from Calgary Air Traffic Control, the pilot's failure to report crossing the Shum Beacon, the deployment of the left thrust reverser in flight, and the inability of the Boeing 737 to safely perform a go-around after reverser deployment on touchdown. The accident led to significant changes in aviation safety regulations, including the requirement for aircraft to be able to safely perform a go-around after reverser deployment.
- The accident was caused by a combination of factors, including miscommunication, pilot error, and design flaws in the aircraft's thrust reverser system.
- The accident led to significant changes in aviation safety regulations, including the requirement for aircraft to be able to safely perform a go-around after reverser deployment.
The Crash of PWA Flight 314
This chapter introduces the setting of the accident, which occurred in 1978 on a Pacific Western Airlines (PWA) flight from Calgary to Cranbrook, British Columbia. The aircraft was a Boeing 737-200, an early version of the 737 family still used by some regional airlines in Canada. Cranbrook was an uncontrolled airport without a control tower, but it did have an instrument landing system (ILS) and other amenities. The pilots were experienced, but the first officer was relatively new to the 737. The weather at Cranbrook was snowy, with visibility reduced to 3/4 of a mile.
The Miscommunication
This chapter focuses on the miscommunication that occurred between Calgary Air Traffic Control and the Cranbrook Air Radio operator. Calgary ATC provided an ETA for Flight 314 that was 10 minutes later than the actual arrival time. This was because Calgary ATC used a different method for calculating ETAs than the Cranbrook Air Radio operator, who was responsible for coordinating ground vehicles on the runway. The Cranbrook Air Radio operator, unaware of the discrepancy, expected Flight 314 to arrive at 1305 and ordered the snowplow off the runway at 1300.
The Snowplow
This chapter explains the role of the snowplow in the accident. The Cranbrook Air Radio operator was monitoring the progress of a snowplow that was clearing snow from the runway. The operator's manual recommended that snowplows be called back only 5 minutes before an aircraft's expected arrival time. However, the operator was using the incorrect ETA from Calgary ATC, which meant that the snowplow was still on the runway when Flight 314 landed.
The Distracted Cockpit
This chapter discusses the distraction in the cockpit that prevented the pilots from hearing the Cranbrook Air Radio operator's warning about the snowplow. The captain was not listening to the Cranbrook Air Radio frequency and was instead chatting with another pilot about the stock market. The sterile cockpit rule, which prohibits pilots from having off-topic conversations during critical phases of flight, did not exist yet. The investigators characterized the pilot's decision to engage in off-topic conversations as unprofessional and poorly disciplined.
The Missed Report
This chapter explains why the pilots did not report crossing the Shum Beacon, which would have alerted the Cranbrook Air Radio operator to their position and the imminent arrival of the aircraft. The pilots were likely distracted and did not follow the customary procedure of reporting their position during the approach. The lack of a formal requirement for pilots to report their position at uncontrolled airports contributed to the accident.
The Go-Around
This chapter describes the events leading up to the crash. Flight 314 touched down on the runway and the captain immediately applied reverse thrust. However, he then saw the snowplow on the runway and initiated a go-around. In the rush to abort the landing, the captain failed to ensure that the left thrust reverser doors were fully closed before applying forward thrust. This caused the left reverser to deploy in flight, creating an imbalance of thrust and drag.
The Crash
This chapter describes the final moments of the flight. The plane lost control due to the asymmetric thrust and drag caused by the deployed reverser. The pilots struggled to regain control, but the plane ultimately crashed into the ground. Only six people survived the crash, while 43 others lost their lives.
The Aftermath
This chapter discusses the investigation into the crash and the changes that were made to aviation safety regulations as a result. The investigation found that the accident was caused by a combination of factors, including miscommunication, pilot error, and design flaws in the aircraft's thrust reverser system. As a direct result of the accident, Canada became one of the only countries to require manufacturers to demonstrate in certification testing that their aircraft could safely go around after a reverser deployment. This type of go-around has since become known around the world as the Cranbrook maneuver. The video concludes by discussing the importance of robust lockout systems and proper training to prevent similar accidents from happening in the future.
