ACARS, I knew someone would say that ! I have to admit to getting a little casual about preflights, flying as I do sometimes 10 or 12 times a day. Reprehensible I know but there we are. However do you check each and every external and internal light every flight, or each and every navaid ? I know I don't, as I won't be using them, however I do at night, just in case.
Cheers DB6