Cessna Citation Sovereign (C680)
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 35; Flight Crew Total 11500; Flight Crew Type 625
Situational Awareness; Communication Breakdown
ATC Issue All Types; Conflict Ground Conflict; Critical
Flight Crew Requested ATC Assistance / Clarification; Flight Crew Took Evasive Action
Airport; Human Factors; Procedure
We received clearance to taxi from tower. The clearance was to taxi runway 05 via alpha into position. This was the clearance that was read back. There are no parallel taxiways at the airport so any taxi operation requires a back taxi on the runway. As we approached the intersection of alpha and runway 05 we checked both directions for traffic and then proceeded. We were half-way onto the runway when I observed a single-engine Piper just lifting off runway 05. We immediately stopped our aircraft and the Piper flew past in front of us. We called tower and reported the Piper and asked if we should proceed. The tower controller seemed confused and finally confirmed our clearance to taxi into position and hold. After debriefing with the First Officer it is our impression that the tower controller had forgot about the Piper who seemed to be doing pattern work at the airport. Both of us never remember hearing any hold short instructions and believe the controller had indeed cleared us into position on runway 05. This incident confirmed that our SOP of visually checking the runway prior to entering is critical to safety of operations. It also confirmed that just a quick check is not enough and we must continue to scan for traffic throughout the taxi.
[Report narrative contained no additional information.]
C680 flight crew reported experiencing a close encounter with a departing PA-28 while cleared to back taxi on MMMM Runway 05.