Commercial Fixed Wing
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown; Time Pressure; Workload
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Other / Unknown
General None Reported / Taken
Company Policy
I was acting as Captain. Before signing in for duty; I was contacted by flight administration and then approached by a contract employee in flight operations to report to medical for a 'before' flight DOT drug screen. Which I will always be fine with; except the union pointed out that this request actually violated regulation regarding uninterrupted (by company/work related duties). I was told I did do the right thing by going to medical office after finally signing in for the test; 'but' I should have then gone home instead of attempting to operate my flight; which will now be 40 minutes late off the gate.Here comes the next issue. After taxiing out to the runway; We did have a flight control computer issue requiring return to gate. After a long delay with maintenance working out a deferral for this issue; we were unfortunately given directive to switch to a new aircraft. At this point it was brought to my attention that my passengers were boarded early on a flight with no captain coming anytime soon. This had our passengers on board this aircraft for a few minutes short of 4 hours. I believe the correct amount of the FAA fine for this approaches 2.8 million dollars.We did disembark pax at this point (way too late). I did check and found out that the FAs did make available snacks and water by the 2 hour mark.The passengers were onboard for well over 3 hours and were never offered any indication that they had the opportunity to deplane. I was very much involved with maintenance and reviewing cockpit procedures for the system deferral. Again I had no idea that the passengers were boarded early for my flight; where it was definitely known that it was never going to leave on time.
Air carrier Captain reported passengers were on board the aircraft for over three hours due to a maintenance issue.