B737 flight crew reported an uncommanded aircraft movement after parking at arrival gate.

Attributes
ACN	1520806
Time
Date	201802
Local Time Of Day	1201-1800
Place
Locale Reference	IAH.Airport
State Reference	TX
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Parked
Flight Plan	IFR
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Multiengine Flight Crew Instrument Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Total 6404 Flight Crew Type 4946
Person 2
Function	Pilot Not Flying First Officer
Qualification	Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument
Experience	Flight Crew Total 8468
Events
Anomaly	Deviation - Procedural Published Material / Policy

Narrative:

After parking at the gate; I received the chocks in signal from the ramp lead. I released the parking brake and started my parking flow. I stepped out of my seat to use the lavatory and as I was getting out of my seat; I felt the aircraft shudder. I turned around and saw that the aircraft was rolling. I directed the first officer to apply the brakes; which he did; and the aircraft stopped. I returned to my seat and opened my window to speak with the ramp lead. The ramp lead told me that one of the ramp workers had placed the chocks under the wrong tire and had pulled the chock to place them under the correct tire causing the aircraft to roll backwards.

Original NASA ASRS Text

Title: B737 flight crew reported an uncommanded aircraft movement after parking at arrival gate.

Narrative: After parking at the gate; I received the chocks in signal from the ramp lead. I released the parking brake and started my parking flow. I stepped out of my seat to use the lavatory and as I was getting out of my seat; I felt the aircraft shudder. I turned around and saw that the aircraft was rolling. I directed the First Officer to apply the brakes; which he did; and the aircraft stopped. I returned to my seat and opened my window to speak with the ramp lead. The ramp lead told me that one of the ramp workers had placed the chocks under the wrong tire and had pulled the chock to place them under the correct tire causing the aircraft to roll backwards.

Data retrieved from NASA's ASRS site 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.