Random drug testing was certainly in force at Bristows in Aberdeen for quite a while before I was "volunteered" into retirement there last September. I know that when it came into force at the request of the clients, they tested some of the chief pilots having given them a few days notice, and I am aware that a non UK national had failed a drug test at the start of his employment at about the same time. I believe it is policy to drug test all new pilot employees at Bristow.
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Mind The Gap