Commercial Fixed Wing
Physiological - Other
Ground Event / Encounter Person / Animal / Bird; Inflight Event / Encounter Weather / Turbulence
General None Reported / Taken
Airport; Weather; Human Factors
I was wing walking the first officer's side of a flight [arriving at the gate] during very cold and icy conditions.  After the aircraft came to a complete stop the pilots shut the engines down immediately and left the APU running.  I waited for the marshaller to give me the clear to approach sign and [then] chocked the aircraft main gear on the first officer's side.  I put the chocks in very tight and even kicked in the rear chock because of the icy conditions.  After both sides were chocked the marshaller gave the chocks in sign to the flight deck and I turned to open the rear pit door while standing on the ground.  I opened the cargo door and as I went to push the door up higher the aircraft released brakes and the side of the door opening hit my arm because the aircraft started sliding back from the stop mark.  Luckily no one was in the way of the aircraft and the passenger loading bridge was not completely up or we could have had major injuries or aircraft damage.  The aircraft slid back approximately three feet before it stopped. It was a nerve racking experience and there was nothing I could do to prevent the situation from happening.
After wing walking the aircraft into the gate and chocking the right main gear; a ramp person was alarmed when the aircraft moved backward approximately three feet. Cold and icy conditions were likely contributing factors to the aircraft's unsolicited movement.