Cross Check ?

[Ms Spurtle]

What's a 'cross check'?

Said by the captain over the PA when taking off & landing.

[Tarnished]

"Doors to Manual and cross check", approaching the gate and "doors to automatic and cross check" leaving the gate.

Each flight attendent is responsible for arming or disaming the escape slide mechanism on a particular door. Apparently they cannot be trusted to do this so the airlines have instigated a cross checking system where another FA checks they have done their door and vice versa.

Better safe than sorry I guess.

Tarnished

[Sven Sixtoo]

"Cannot be trusted"

Bit harsh I think.

The operating procedures for many safety-critical systems require that one person does the action and someone else checks that it has been done.

Not a reflection on the competence or diligence of the first person, just a lesson learned through bitter experience on how the human brain functions, and what the process leading to error can be.

Sven

[HZ123]

A lesson that is not a total success as chutes are still activated because CC have failed to cross-check.

[Sven Sixtoo]

HZ123

And just out of curiosity, when the gangway thing is up against the door (with the ground Ops people in the end of it?) what happens when the CC opens a door set to Auto?

Sven

[Kempus]

Hi,

Being someone who cannot be trusted i'd thought i'd add my bit.

As Sven Sixtoo said pratically all safety related procedures require double checking and this process applies also to the flight crew as well so to say they cant be trusted is not right in my opinion.

Some aircraft also operate with only one crew member per pair of doors so there is no one to cross check with so they gotta get trusted with that!

As for slides still deploying, yes it does happen but it has been proven through notes in the aircraft defects log that the slide was deployed mostly by pilots or ground engineers. Main reason for this is that they really only open the door from the outside. When the door is opened from the outside there is a mechanism which disarms the door should it still be in automatic and, we're all human, they forget this and open the door from the inside with the door armed.
(know there are some aircraft this dosen't apply too like the 737 which involves manually attaching the slide to the grit bar which can only be done from inside the aircraft)

Now for the door being opened with the jetty attached the slide wouldn't infalte. Reason behind this is that the slide needs to fall about six feet for the infaltion cord to be activated. A good example of this is the Air France or Britannia Airways crash where when the aircrafts left the runway all the landing gears collapsed redusing the height of the aircraft from the ground dramatically.

http://www.airliners.net/open.file/565590/L/

As you can see from the photo the slides at door 1 and 4 are uninflated and on the ground. The slide at door 2 is inflated becuase as crew you are trained to pull the manual inflation cord incase the automatic inflation cord fails. Of course on the day you judge if you should do it depending on the crash situation and aircraft attitude and what will assist a speedy escape. So in terms of the slide at door 2 its inflated due to the crew member going into auto mode!

Cant find the pics of the Air France crash but the pic i mean is the one taken by a passagnger from the out side just in front of the nose as the fire breaks out. Think it was maybe taken on a mobile!

Hope this helps!

kempus

[Curious Pax]

I stand to be corrected, but many many moons ago when I worked for Servisair there was a tale around that DC10s had explosive bolts which blew the door away from the aircraft when opening with the chute armed. It was claimed that the door was opened on a DC10 in the US by a dispatcher on an airbridge, and the door fatally blasted him back up the air bridge. Anyone able to confirm or deny this possibility?

[Tarnished]

My what a super sensitive bunch you are.

My comment of "apparently cannot be trusted" was against the malaise that pervades everything we do today. Nobody is allowed to be responsible, there is so much "checking six" (@rse covering) that it is easy to forget that you have a brain and are allowed to use it. This is not a dig against any FA or any member of the aviation industry.

If anything its a dig against the litigation happy legal fraternity.

Why does the announcement have to add "and cross check"? surely the FAs are sufficiently well trained to know that when they arm/disarm the doors a cross check is mandated by procedure?

Anyway sorry for ruffled feathers

Tarnished

[Kempus]

No ruffled feathers! sorry if it came across that way!

The "cross check" varies with airline, i work long haul BA now but before i was with TCX and they never used that phrase as their door arm/disarming procedure is different . Each process was said out to the other crew member who would reply with "confirmed" or "stop" before each action so it was a case of pointing at the arming lever before moving it.

My only reasoning with BA is with the double checking of everything safety wise just like in the flight deck as they still read from a check list to make sure all is done right. You'd think that when landing, having the gear down would be a good idea but they still verbally double check!!

As for the DC-10 door, as i said all aircraft are different but what has prob happened there is that when the aircraft pulls onto stand the dispatcher knocks on the door, he should stand back and there should be a delay of 10 secs before the door is opened.

On most large aircraft the doors are power operated when the door is armed to aid with quick door opening in an emergancy as the doors are bloody heavy! The "power assist" as its called, is in the form of a compressed spring or compressed nitrogen acuator.

As the dispatcher knocked on the door he's stood by it to help the crew member open it as with the door disarmed there is no assistance to move it. (except the likes of the 767 with the door goes up and it can be moved electrically)
The door has still been left in the armed position causing the power assist to activate throw the door open hitting the dispatcher. The doors open at some speed when the power assist is activated and it is known that some crew members have been catapolted out by not letting go of the door causing death or serious injury as they fall 12 odd ft or more.

As i said before all aircraft are different and having never flown on a DC-10 i'm not sure the exact door mode but using knowledge i know now and also gained as i studied aircraft engeineering for an apprenticeship pre 9/11 when the course was disbandoned due to the events on that day.

Hope this helps an feel free to ask any more questions that you may want answered.

kempus