distress signal when triggered by a crash. so why didn't any of the four work? let's be joined by jeff wise. there's four on board. >> right. >> aft door. one in the fewle latch. and the compartment. >> right, when you say forward door and aft door, what we're talking about the life rafts in the case of ditching can deploy. and when a life raft deploys you have the signal being sent from the elt. >> it's the impact that makes it emit a distress signal, right? >> the fuselage, that means really back by the tail. so, yeah, when the plane hits something, when there's a deceleration, essentially, when you get a g-force that's strong. not a hard landing but something more significant than that, then it can activate it, send out a signal. the one on the door, in the life raft, those activate when the