My understanding wild car operation is when a duplex or group looses the master car (power could just be turned off) so the other car goes into wild car operation because the hall calls won't work without the master car on. The slave car will run floor to floor to floor to keep service to all floors. So if your in the hall eventually the car will stop on your floor and open the doors.

Maybe someone else can chime in on this, I've only been explained the theory on this one, I've never seen it happen. It sounds like you'd only find this on older relay logic stuff as newer stuff doesn't rely on one car being operational for the hall calls to function.