picture shows the inside of one of the main doors
in a large commercial jetliner. After closing the door,
the flight attendant
attaches the emergency slide on the inside of the door.
After attaching the slide,
the attendant attaches this red strip
across the window. It is
meant to signal
to a person
outside to not open the door.
Opening the door could be deadly since the
emergency slide would automatically inflate.
It seems like it
would be very easy to forget to attach the red
there is a strong likelihood
of forgetting a critical step in
a hazardous procedure, it would be better to
have an automatic way of doing that
step. For example, a better solution
would be to have a sign or signal that
automatically occurs when the slide
In the case of the escape slide warning tape, newer aircraft door
designs actually do what you suggest - there is a mechanical flag
that moves into view when the slide is armed. -MR