News release

Associated links (R17Q0061)

Undesired release of air brakes led to 2017 uncontrolled movement of rail cars north of Sept-Îles, Quebec

Dorval, Quebec, 10 September 2018 –  In its investigation report (R17Q0061) released today, the Transportation Safety Board of Canada (TSB) determined that bottling of the air in the brake pipe during switching operations led to the July 2017 uncontrolled movement of rail cars in Mai, located 128 miles north of Sept-Îles, Quebec.

On 25 July 2017, a southbound Quebec North Shore and Labrador Railway (QNS&L) train, consisting of 159 loaded iron ore cars and 2 locomotives, stopped in Mai to add a locomotive and to relieve the locomotive engineer. The two locomotives were uncoupled from the cars to make room for the additional locomotive. A few minutes after the locomotives were uncoupled, the cars began to roll uncontrolled and passed a signal. The relief locomotive engineer, who was working nearby, took action to stop the movement. There were no injuries and no damage.

The investigation found that, while securing the train, the locomotive engineer closed the brake pipe angle cocks (valves at each end of a rail car or a locomotive used to open or close the brake pipe) between the locomotive and the first car before the air had fully exhausted from the brake pipe. With the angle cocks closed, the air became bottled in the brake pipe, leading to an undesired release of the air brakes. When the air brakes on the cars released, the hand brakes that were applied did not keep the cars in place. Consequently, the cars rolled uncontrolled for about 400 feet past a signal before being stopped when the relief locomotive engineer fully opened the angle cock.

The locomotive engineer was not used to following the procedures that consisted of leaving cars with only their service brakes applied during switching operations. He and other company employees often used the emergency brakes, which was contrary to company procedures. If railway companies do not ensure that employees are completely familiar with operating procedures they must follow, some procedures may not be well understood or applied, increasing the risk of accidents.

Following the occurrence, QNS&L clarified its operating procedures regarding brake pipe uncoupling and the minimum number of hand brakes to be applied. Training regarding these changes was also developed and delivered to all QNS&L locomotive engineers.

See the investigation page for more information.


The TSB is an independent agency that investigates air, marine, pipeline, and rail 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
Media Relations
Telephone: 819-994-8053
Email: media@tsb.gc.ca

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