Fire alarm ignored
A worker knew the time and place of the next practice fire drill in a nearby building, so he knew he wanted to be in his own building at that time to prevent his work being delayed. However he needed to obtain some documents from a nearby building first, and in doing so, he heard the alarm. Unfortunately, he hadn't been paying attention and walked through a real emergency which started about 20 minutes prior to the practice drill.
All alarms must be treated as real. If practice drills are widely publicised or always occur at fixed times ("Oh, it's 10 o'oclock - must be a drill!") then the speed of turn out can be poor. Ideally only the fire warden should know the time of the next practice, and the time should be varied.