When flying on a commercial airline, upon pulling up to the gate you’ll usually hear a flight attendant say over the intercom “disarm doors and crosscheck.” Soon thereafter you’ll usually hear another say “doors disarmed and crosschecked.” What does this mean?

Commercial airplane doors have emergency evacuation slides to be used in the case of an emergency.  These slides are designed to inflate in about 10 seconds and are automatically inflated by opening an “armed” door of the plane. Thus, in order to open the door without the slide inflating the door must be disarmed. The term “crosscheck” means that one flight attendant has checked the other’s work, meaning that the fact that the doors are disarmed is confirmed by a second flight attendant. Here’s some photos of what it looks like when doors are not disarmed prior to their opening:

Having the above situation occur is a major bummer.  In addition to being embarrassing, it costs about $20k to reset the inflatable slide and ground personnel or people inside the plane can be injured.