I appreciate the negatives, particularly in relation to cockpit avionics, but I was working on a scenario of being able to obstruct access to the cockpit for long enough to allow an aircraft to make an emergency landing; if that had to be done with secondary instruments, so be it; once the aircraft is down, the b******s can be taken in for a chat and a good beating and any (aircraft!) damage should be rectifiable. THIS WOULD STRICTLY BE AN OPTION OF VERY LAST RESORT.