Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Flight Crew Last 90 Days 465
Distraction; Fatigue; Situational Awareness
Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Loss Of Aircraft Control
Flight Crew Regained Aircraft Control
Human Factors
We pulled in to [the gate]. The Captain began his shutdown flow and either forgot to set the parking brake or somehow it was released. I went to grab the checklist and out of the corner of my eye; I noticed we were moving backwards. The Captain immediately applied the brakes and they connected the tow-bar and towed us back to the line after we made sure everyone was back in their seats. It was a really long day with a weather diversion and almost timing out. We were eager to get the passengers on their way after a very long flight. We had started the checklist and I did not visually verify that the parking brake was set when I was completing the parking checklist.
B737-800 First Officer reported failing to ensure parking brake was set after taxi into gate.