Refuelling accidents are mercifully rare but when they do happen, the consequences are usually severe.
JatA1 is either dispensed using a bowser or at larger airports by a hydrant system, with a truck containing measuring and filtering equipment connected between the pot on the stand and the aircraft. The fuel is delivered at a pressure of around 11 bar. If (as has happened) another vehicle drives into the ground connection and snaps it, the plume of jet fuel reaches 150' in to the sky before the automatics detect the sudden loss of pressure and shut the system down. The reason for using a static line for JatA1 is that many thousands of volts of static electricity are generated by the fuel during the dispensing process. Whilst the pressure couplings aren't open to the atmosphere, the insides of the tank are.
Another danger with JatA1 fuelling is that if there is a fracture in the line, then fuel can be sprayed on to a hot surface, such as an aircraft engine or the running engine in the fuel dispenser. A refueller sadly lost his life during the refuelling of a BA 777 at Denver in 2001.
I can't recall a fuelling accident to a light aircraft attributed to static discharge but there are quite a few videos on the internet of car fuelling fires. Allegedly, in the United States, these are sometimes caused by the synthetic fibres worn by people rubbing themselves against the bodywork. In one case, I think someone was attempting at night to see if fuel was flowing by the light of the flame from a cigarette lighter. A Darwin award contender, surely!
It only takes a few seconds to attach and then detach a static line to and from an aircraft. There are those folk who have taxied away with the line attached - very embarrassing.
TOO