What can lead to the revocation of flight engineer and pilot certificates?

The revocation of flight engineer and pilot certificates can indeed occur as a result of refusing to submit to a drug or alcohol test. Regulatory authorities place a high priority on safety, and stringent measures are in place to ensure that pilots and flight engineers adhere to rules regarding substance abuse. When an individual refuses to comply with these testing requirements, it raises significant concerns about their commitment to safety and regulatory compliance. Thus, such refusal can lead to serious disciplinary actions including the revocation of their certificates.

While other actions, such as flying without a valid license, not completing required training, and improper maintenance of the aircraft, could lead to suspension or other penalties, refusing a drug or alcohol test is particularly serious because it directly relates to the competency and fitness of the crew to safely operate an aircraft. This is why the refusal to submit to testing stands out as a substantial violation that can result in certificate revocation.