There's a one minute timerish by default where if you were unable to send/receive information from the server you do get booted out. This is what happens when you crash out too, it takes a minute.
I assume by design this was done because if it was any shorter, people would be far more often booted from the server for experiencing momentary, awful lag. It's a design compromise, talk to Beamdog on their forums if you want that changed.
The very nature of a crash is that you arent sending information to the server, so you can't tell it you have crashed. Nothing the developers can do about that without creating some kind of external app for booting characters to save people ~60 seconds.