Narrative:

[We] pushed back from the gate without first receiving pushback clearance. How did this happen? I don't know. It was leg 18 of 19 on a 4 day trip. Yes we were tired; but I would not say that we were fatigued. [We had] communications problem with the ramp/tug driver. [They] had to get another headset. ATC switched runways as we were ready to pushback. Get new ATIS; reprogram FMS; brief new departure procedure and verify FMS info. Ramp asks if we are ready and without thinking about it I say we are cleared to push. Both of us; captain and first officer; didn't realize that we did not have a clearance until ATC contacted us during the pushback. Yes it was our error; but playing it back over and over in my head I was sure that we had received a pushback clearance. Tired enough combined with being busy enough that I got distracted into expecting what was supposed to happen next.

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Original NASA ASRS Text

Title: Q400 Captain reports pushing back without clearance from Ground Control after a runway change with the attendant clearance and FMS changes.

Narrative: [We] pushed back from the gate without first receiving pushback clearance. How did this happen? I don't know. It was leg 18 of 19 on a 4 day trip. Yes we were tired; but I would not say that we were fatigued. [We had] communications problem with the ramp/tug driver. [They] had to get another headset. ATC switched runways as we were ready to pushback. Get new ATIS; reprogram FMS; brief new departure procedure and verify FMS info. Ramp asks if we are ready and without thinking about it I say we are cleared to push. Both of us; Captain and First Officer; didn't realize that we did not have a clearance until ATC contacted us during the pushback. Yes it was our error; but playing it back over and over in my head I was sure that we had received a pushback clearance. Tired enough combined with being busy enough that I got distracted into expecting what was supposed to happen next.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.