“ Cabin crowd , weapon system doorway and crosscheck ” is the instruction delivered over the plane ’s public computer address . In - trajectory staff then pull a metal lever tumbler on each door before bond a little red ribbon across the windowpane of every exit , and we ’re all conceive the same thing : that flimsy sheet ca n’t be doing much .
In reality , though , this limp piece of low - tech equipment could bring through someone ’s life . Specifically , emergency servicesattempting to go in the aircraft from the outside rely on the front of this deep red tapeline to warn them that the threshold is armed , and that opening it could place them in serious danger .
By armed , we mean that the sheet ’s excretion microscope slide is engaged and quick to be deployed . give the doorwill therefore cause the slide to fritter out and inflate with explosive force , potentially crushing anyone who find to be bear in front of it .
In accordance with the Federal Aviation Administration’ssafety requisite , all commercial aircraft must be fitted with equipment that ensures they can be evacuated in under 90 moment , even when in the dark and with half of the exits stymy . To facilitate this , evacuation slides must fully inflate in six second , engage in temperatures range from -54 to 71 ° C ( -65 to 160 ° F ) and in winds of up to 25 knots ( 46.3 kilometer per time of day ; 28.8 Roman mile per minute ) .
Prior to going , the cabin work party will be instructed to arm the door , at which point they tie the folded - up coast to the door by pull out a lever . launch the door will therefore cause the slide to go down out , pulling on a laniard that set off the pomposity mechanism .
“ Crosscheck ” , meanwhile , is the command for the cabin crew to find out that their colleagues stationed at the threshold opposite their own have successfully armed the loss and placed the warning ribbon across thewindow .
When a threshold is opened , a powerful burst of compressed atomic number 6 dioxide and nitrogen gas is accelerate through a series of aspirator within the lantern slide , immediately inflate it to about one - third of its electrical capacity . This also creates a vacuum that draw surrounding melodic phrase into the aspirator through louver , which then shut down when the slide is fully inflated a few moment later .
Firefighters and other rescuers therefore need to get it on if a threshold is build up in monastic order to avoid being squished , and the crimson palm across the windowpane is their only clew .
Thankfully , though , the piddling ribbon is rarely required as the vast majority of flight of stairs strain their terminus without incident . It ’s therefore up to the cabin crew to disarm the doors before they can be opened to allowpassengersto leave .
The instruction to perform this task will usually be along the lines of “ door to arriver and crosscheck ” , at which point the cabin crew will return the levers to the unarmed lieu – thus disconnecting the slides from the threshold – before removing the red warning ribbon and checking that their colleague have done the same at all adjacent door .
At which tip , the magic words will be speak : “ You may now disembark the aircraft . ”
