Its been in force in other areas of the transport industry for a while. Generally the way its enforced is two fold:
- Random testing where a specialist screening company turns up on site and randomly picks staff members to provide a sample in a cup! This is sent away and results appear a week or so later.
- During promotion or relocation you attend an actual medical centre before taking up your new duties and go through same process. The difference being that you know this one is happening.
The random one tends to get those who have had a few too many the night before but both will catch those who have been taking something a bit stronger than nicotine.
So the old Bill won't be following you down the taxiway with blues-n-twos...