EMB-175 flight crew reported they did not set the parking brake before continuing with the shutdown flow. The aircraft moved momentarily backwards before the Captain reset the brakes.
Synopsis
EMB-175 flight crew reported they did not set the parking brake before continuing with the shutdown flow. The aircraft moved momentarily backwards before the Captain reset the brakes.
Narrative
Parked at the gate with #1 running; #2 shutdown; and APU on. CA (Captain) held the brakes and made the hand signal for parking brake set. After shutting down #1 and completing shutdown flow; CA called for shutdown checklist. When I called for Parking Brake" we both noticed the parking brake light was not illuminated. Aircraft likely already rolled backwards a few feet at this point. CA depressed the brake pedals again to prevent us from rolling further; and he reset the parking brake. Ramper contacted us to discuss the issue and we agreed to re-capture to get towed back to the appropriate spot for the jetbridge. Aircraft was repositioned to normal position; parking brake was set correctly and confirmed on; we re-started the shutdown checklist; and finally the cabin was deplaned as normal.Cause: Emergency/Parking Brake not set before continuing shutdown flow. FO did not have toes on the brakes as a backup.CA should use left hand for the parking brake hand signal and right hand to set the parking brake every single time so that it is not skipped by mistake on the shutdown flow. FO should know this flow and cross-check the CA's actions. FO should keep toes on the brakes until shutdown checklist is complete just in case the parking brake is not set correctly or fails."
Second reporter narrative
Taxied into the gate with #1 engine running and #2 shut down. Parked normally and shut down number 1 engine followed by shutdown flow. Called for the shutdown checklist and when Parking Brake" was called by FO; we noticed the parking brake light was not illuminated. I immediately stepped on the toe brakes to ensure the aircraft was stopped after which I reset the parking brake. The ramp then contacted me on the headsets to discuss why the aircraft had rolled back and advised that he would connect the tug and reposition the aircraft back to its normal position. The aircraft was repositioned and the flight was deplaned as normal. Improper positioning/verification of the parking brake being set. Maintain extra vigilance during pushback/parking operations to ensure the parking brake is properly set and the proper indication is shown on the switch light."
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.