Jetstar - to crosscheck or not to crosscheck?

[Jack B]

Do all airlines have the procedure of cracking the door on the 737?

[Owen H]

Which Boeings?

From memory NONE of the boeings have an automatic disarm.The only thing that saves an airbus is a red light comes on in the door if you start to open it from the outside and it is still armed.But they might have changed it on the later Busses

The 767 and 747-400 certainly do.

747 - "When the door mode select lever is in ARMED position and the door is opened using the exterior door handle, the door mode select lever mechanically positions to DISARMED and the door may be opened without slide deployment".

767 - "The emergency door opening system and the slide are automatically disarmed when the door is opened from the outside."

This is why many airlines procedure is to open the door from the outside at the gate.

The door-cracking on the 737 makes sense if it does not automatically disarm.

[Brendan Lawrence]

I'm trained on Airbus so I can't speak from fact about Boeing doors other than what I've learnt from my housemate who is crew for Virgin Blue. And I have been told about the 'cracking' of the doors on the 737 immediately after doors are disarmed, which indicate to ground staff that it is safe to fully open the door from the outside.

Regarding the lights on the Airbus door (which are located in the viewing window portal for cabin crew and staff on the outside to see) - there is a red cabin pressure warning light that will start flashing if doors are disarmed on arrival and there is residual cabin pressurisation which could cause the door to open with explosive force. I think this is when the pressure outflow/outlet valves have not correctly depressurised the aircraft during descent. The other light is a flat white light which will illuminate with the text "SLIDE ARMED" when the door operating handle even slightly starts to be rotated upward whilst the door is armed - another added safety feature.

[Adam G]

The B777 also automatically disengages when opened from the outside.

On the B737 because the girt bar is manually moved into the floor brackets there is no way to disarm it from the outside. Cracking the doors achieves 2 things - firstly it actually takes a lot to blow a B737 slide - I've seen crew crack & reclose doors in the armed mode & not deploy the slide - the slide won't actually deploy until it folly drops out of the bustle. Secondly they are cracked so early that in the remote chance the slide is accidently blown it's before all the GSE & ground staff are close enough to wear it. The B737 would be the easiest of most aircraft to get an accidental demployment on though because cabin crew are actually manipulating the door handles in normal operations.

On most other aircraft cabin crew don't open or close the doors in anything except an emergency, as a result they don't ever usally touch the door operating handle so tend not to accidently operate it.

A lot of operators still do cross check however (mine does) - it serves other purposes apart from preventing accidental deployments - specifically it actually checks that the door is armed correctly so if a deployment is necessary the slide will actually deploy.

[Jack B]

Did the same apply to 707's? I know they had the same girt bar design as the 737, however in the 60s and 70s I'm not sure if airlines even required the doors to be armed in normal operations