Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 234; Flight Crew Total 9786; Flight Crew Type 9786
Communication Breakdown
Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown
General None Reported / Taken
Human Factors
We were given pushback clearance by ZZZ Tower and told push crew cleared to push. ZZZ is small airport and we were the only aircraft moving on the ground that I heard. Tower controls air; ground and clearance. The English spoken was very good and at no time did I think the communications were not understood by anyone. During pushback the ground crew told us cleared to start both engines. The Captain called for start of both engines 2 then 1. We needed 5 minutes warmup and it was a short taxi to Runway 10 for departure. During second engine start I hear something like 'brakes brakes set parking brake.' I look down and parking brake was not set then outside and I didn't see the aircraft moving. The Captain set the parking brake and asked if everything was ok? We were told it was and that the tow bar was disconnected and bypass pin removed. The Captain again asked if everything was ok. We were told yes. Captain told crew cleared off headset. We received a salute. Second engine was fully started. Everything did not feel ok. Had we missed set parking brake instructions? Had the Captain missed setting the parking brake? I could not recall hearing to set parking brake. Neither can I recall hearing Captain saying parking brake set. The Captain did not recall this either. I was starting the engines but am pretty good at multitasking and I am good at when Captain says parking brake set verifying parking brake red light on and pressure normal. Something was not as normal. It was like the ground crew never told us to set parking brake after pushback completed? Or the Captain never set the parking brake when told to do so? We never saw the aircraft move or felt it move during this undesired moment. No one was hurt. No equipment was damaged. Something somewhere was not right. We just don't know what. We took a quick breather. I never felt rushed. I thought everyone understood all communications spoken. We followed SOP. Still we had a moment that could have been disaster in one or more ways. It left a sour feeling with both of us. Then we snapped out of that feeling and proceeded with the after start checklist and on to ZZZ1.
Flight Crew reported communications breakdown during pushback.