Cessna Citation Sovereign (C680)
Flight Crew Multiengine; Flight Crew Instrument
Communication Breakdown; Situational Awareness; Confusion
Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Loss Of Aircraft Control
Flight Crew Became Reoriented
Airport; Procedure; Human Factors
We called the FBO upon taxiing in. Line Service said park anywhere up front. I found a yellow parking line and offloaded the passengers. Line service said we were parked in the 'airline area'. There were no SIDA (Secure Identification Display Area) red markings anywhere. Line service said we could either start up and move or he could tug us. I requested the tug. He brought the tug and asked me to release the brakes. I went on board; shut the door and released the parking brake. I went in the back to tend to the cabin. The plane was slowly moving backwards at what I perceived to be a normal towing speed. I happened to look up and see the tug not attached to the plane. I pulled the emergency brake and stopped the aircraft. The nose wheel scissors were spun 180 degrees exceeding the 90 degree restriction. I asked the line service guy what happened. He said the plane started to roll when he was hooking up the tug. The plane didn't hit anything and did not depart the paved surface. It rolled about 75 feet.I should have double checked the line guys work and made sure The plane was chalked before I released the brakes and not just trust his release the brakes request. Also the ramp should be marked as a SIDA area with red lines as normal. The FBO should be clear when they're not out to park us and not say just park anywhere up front.
CE680 pilot reported they parked in an area designated for commercial aircraft because it was not properly marked and had to be towed to the correct area. The tug driver told the pilot to release brakes and the aircraft rolled backwards prior to being attached to the tug.