Just don't tell anyone you use pot. The only way the gov't would know you use is if you registered with Hellth Canaduh to legally grow medical pot and you wouldn't do something silly like that would you?
Do they piss test pilots before every flight these days? Or just if there's an 'incident'?
In the 15 years or so I was driving truck in the oil patch, but not employed by the oil companies directly, there was always the threat of a random test but I never got one nor had an incident serious enough to make them want to test me. I was mildly high every day and all day with little tokes in my pipe. Driving was such a mind-numbing job that is was best to be a little numb before you even turned a wheel.
The rig pigs would get tested for pot fairly often so they did crack instead. Much safer.