what do airlines themselves do to prevent the crews from flying over the limit/under the influence?
SevenOfNine:
All US airlines are required by regulation to administer a DOT approved drug and alcohol misuse prevention program. This includes initial and recurrent training related to alcohol and drug abuse effects upon work performance. In other national jurisdictions like the UK, they have their own laws in effect that are similar but differ in some respects.
For US airlines, pre-employment, random and "for cause" (post accident and reasonable suspicion) drug and alcohol testing is mandatory for all employees working in "safety sensitive" positions. By law, the rate of random testing is determined by the percentage of positive test results throughout the national testing pool. So each "covered" worker is subject to pre-employment and random testing and may also be tested if reasonable suspicion is found to exist. Refusal to submit to testing is disqualifying and subjects the individual to sanctions. Any flight crewmember involved in an accident WILL be tested. (whether they survive the accident or not)
Most positive tests in the aviation industry are found in the required pre-employment tests. Flightcrew have an extremely low rate of positive tests, however they do find one occasionally.
Aside from the testing program, many companies including airlines operate an Employee Assistance Program which caters to employees who choose to voluntarily self disclose and receive treatment for substance or alcohol abuse before they are caught. (or worse)
In at least some companies, part of a flightcrew member's training is the recognition of cognitive impairment for whatever reason in oneself and fellow crew. Factors such as fatigue, sickness or emotional distraction are just as potentially dangerous as drug or alcohol impairment. Most professional pilots I've worked with will refuse to fly with anyone who they have reason to believe is significantly impaired by any cause, and especially if their impairment is believed to be caused by drugs or alcohol. There are no established and accepted objective tests for fatigue or other causes not related to intoxicant substances. Maybe someday there will be a reliable and objective pre-flight cognitive function test and maybe not. I hope that answers the question satisfactorily.
I'm happy that drug and/or alcohol use has become a rarely encountered problem in the flight operations business. But I'm equally unhappy with the fact that the aforementioned other causes of cognitive function impairment are not addressed by industry management or safety regulators with the same vigor as drug and alcohol impairment. Maybe THEY are the ones who should be presumed guilty of impairment until they provide proof of their sobriety!
So no formal charges against the pilot who is the subject of this thread eh? To me that brings into question the basis for his removal and arrest in the first place. Procedural legal error or technical problem with the testing equipment? Something else? As for the airline's internal investigation, I wouldn't expect to hear anything about that unless the airline somehow finds something they believe is in their own best interest to share with the public. There is no legal requirement that they do so after all.