Germanwings flight 4u9525 CVR.

[manzini]

Yes cost, In plain, this is my first justification, but the cost of any replacement, or aprovisioned piece by operative regulations is huge.

A simple whell-screw costs 300€. The parts used for progressive braking the plane, 3,500€ per unit. Each wheel have 11 of these.

I believe that using the current infrastructure for in flight mobile or internet, used to monitor the aircraft would cost less than the entire set of wheels.

A wheel is vital piece. From today, also the remote door control.

[G0HZU]

Decompression, as in a flaw in the fuselage that allows pressure to reduce to ambient at 38,000 feet, isn't hard to diagnose.  Eardrums bursting, sudden cold due to adiabatic expansion of the air, and immediate fog would be clues, as well as the gauge on the panel showing the cabin altitude increasing (the cabin pressure is indicated as an equivalent altitude, not directly as a pressure).  The noise of decompression would have been heard on the CVR

.

decompression doesn't have to be sudden. I've seen documentaries on the TV where people are deliberately flown up to higher altitudes in an unpressurised plane and they sit there without an oxygen mask as an experiment. They begin to suffer subtle symptoms as the pressure slowly decreases and eventually they can't even do simple tasks like write their own name down on a piece of paper. Their blood oxygen levels begin to fall yet they are still awake and unaware how ill they are. I seriously doubt that their eardrums burst at any point. I guess it must be similar to a diabetic going a bit hypo.

But he wouldn't pass out if he had the O2 mask on.  He also wouldn't pass out if there had been no genuine decompression, and the evidence suggests no genuine decompression.  Finally, the CVR indicates the sounds of people banging on the door to try to break it down, and people screaming.  If the air were insufficient for a seated pilot to maintain consciousness, it would be much less sufficient for someone standing and moving around, with the kind of exertion required to bang on the door like that.

Yes he could if he was genuinely ill. I'm not sure you understood the reasoning behind my post.  I proposed that he fell ill and wrongly 'thought' he was suffering from decompression symptoms.

i.e. in my scenario there never was a decompression. If someone had a partial stroke or seizure then putting a mask on isn't going to help much is it? They can still pass out eventually if they have a seizure.

Closing the door would do absolutely nothing for oxygen levels, and a pilot knows that.  The air at altitude is about 80% nitrogen, 20% oxygen, the same as at sea level.

I wasn't referring to the relative composition of the air, rather than the qty of air molecules.  I assume (wrongly?) that the cockpit would be designed such that with a closed and sealed door it would be able to maintain pressure longer than if the door was opened whilst there was a degree of pressure loss in the main fuselage? It would make sense to me at least to keep the cockpit door closed in that scenario.

However, I've now seen some more information that has been released that suggests the copilot became less sociable to the pilot as the flight reached cruising altitude. So maybe they had a few words and the copilot then planned to crash the plane?

[AF6LJ]

There was an unconfirmed report that the chip was 'missing'

Someone might get fired over that one.

[AF6LJ]

This is how the door system works on an Airbus:

Allegedly now it is said, that the copilot closed the door from the inside mechanically, so it could not have been opened by the pilot from the outside.

Thanks to 9/11 mass paranoia 150 or so people are now dead.
You can't make the world safe, people who want to be safe should live in the nearest maximum security prison, they can find the best safety there.

The second lesson of this tragic accident is the assumption that you can stop a deranged person from gaining access to an airplane to fly into the ground, a building of a school full of children. History has shown that mad men (and woman) have made their way into trusted positions, including the highest of government positions (they seem to be able to access those positions much easier than the flight deck of an airliner).

So what have we learned from this lesson?
No matter how large the Government institution, it is unreasonable to expect them to maintain your safety, that is the job of the individual.

[mikeselectricstuff]

Apparently the US, but not Europe,  have a rule that if flight crew leaves the cockpit, a member of cabin crew must replace them while they are out.
Seems sensible.
 

[Wytnucls]

It will probably be implemented shortly. It should have been made a requirement much earlier, after a string of incidents involving the locked cockpit door and suicidal personnel. Some people in high places will be highly embarrassed.
In retrospect, a security system that can lock the captain out of his cockpit, seems like a dumb idea. At least, give him a personal security code to immediately override the door locking mechanism.

[AG6QR]

Yes he could if he was genuinely ill. I'm not sure you understood the reasoning behind my post.  I proposed that he fell ill and wrongly 'thought' he was suffering from decompression symptoms.

i.e. in my scenario there never was a decompression. If someone had a partial stroke or seizure then putting a mask on isn't going to help much is it? They can still pass out eventually if they have a seizure.

Pilots are taught very early in training to trust their instruments more than their subjective feelings.  There is a gauge in the cockpit that displays the effective cabin altitude.  If a pilot were feeling a bit ill and suspecting hypoxia, but not seeing obvious signs of explosive decompression, the pilot would check the cabin altitude and don his oxygen mask before starting an emergency descent.

[a210210200]

It will probably be implemented shortly. It should have been made a requirement much earlier, after a string of incidents involving the locked cockpit door and suicidal personnel. Some people in high places will be highly embarrassed.
In retrospect, a security system that can lock the captain out of his cockpit, seems like a dumb idea. At least, give him a personal security code to immediately override the door locking mechanism.

Given them a code such as that could allow a terrorist to obtain the code and defeat the door lock with no means of the flight crew stopping them. The pilot might forget or otherwise write the code down somewhere. Under severe stress they may give up the code.

I think a multi-crew system where each cabin crew member has a simple key device which contains the cryptographic code which they all need to use together to override the door. To prevent terrorists from abusing this mechanism each crew member can erase their key in the event of a serious situation. This way the cabin crew can override the door if needed without risking a door override that is malicious.

A pilot who wants to commit suicide will have to attack other crew members outside the cockpit to disable this mechanism which would allow the crew to lock down the cockpit by having the remaining pilot lock the door and the crew erase their keys. Trapping the attacker outside.

If the malicious user is in control of the flight deck the crew outside can all use their devices to gain access to fight back.

[a210210200]

Apparently the US, but not Europe,  have a rule that if flight crew leaves the cockpit, a member of cabin crew must replace them while they are out.
Seems sensible.

This doesn't actually fix the whole door lock override problem as a suicidal person could just kill or otherwise incapacitate the person with them and then we are back to square one. Assuming someone is willing to commit suicide and kill everyone with them it certainly is possible. A fellow co-worker would not expect to be attacked/murdered so there is the element of surprise which is bad.

Having a multi-part override fixes the door lockout problem while not compromising the door security as crew outside can erase their keys and getting all of them without this occurring would be very difficult unless everyone was working together.

[cimmo]

Any speculation regarding a decompression,  either catastrophic or gradual, is NOT supported by the evidence provided by the CVR (assuming the reports are correct). A catastrophic decompression makes a heck of a racket and so do the cockpit alarms when a gradual decompression occurs. None of these noises have been reported.
Also, if a pressure differential is detected between the cockpit and the cabin, the electrical door locks disengage allowing the door to open freely to equalise the pressure differential. If this didn't happen, the door and or bulkhead structure could easily be damaged by the 8.5psi pressure. That force could total several dozens to hundred tonnes over the area of the door/bulkhead.
 
Relevant info directly quoted from the A320 flight crew manual:
A forward-opening hinge door separates the cockpit from the passenger compartment. It has three
electric locking strikes, controlled by the flight crew. In normal conditions, when the door is closed,
they remain locked. When there is a request to enter the cockpit, the flight crew can authorize entry
by unlocking the door, that remains closed until it is pushed open.
When the flight crew does not respond to requests for entry, the door can also be unlocked by
the cabin crew, by entering a two to seven-digit code (programmed by the airline) on the keypad,
installed on the lateral side of the Forward Attendant Panel (FAP).
The door is bulletproof and fully compliant with rapid decompression requirements.
A mechanical override enables the flight crew to open the door from the cockpit side.
A deadbolt is installed at the level of the center latch area of the cockpit door. This deadbolt bolts the
door from the cockpit side, in the event that more than one locking latch strike fails, or in the case of
a total CLS failure.
*** (Note - this deadbolt is NOT on ALL A320 aircraft, just a specified serial number block. I have not been able to ascertain if the Germanwings aircraft was so equipped)

The Cockpit Door Locking System (CDLS) provides a means of electrically locking and unlocking the
cockpit door. This system is mainly composed of :
- A keypad, located in the forward cabin, near the cockpit door,
- A toggle switch, located in the center pedestal’s Cockpit Door panel,
- A control unit and its CKPT DOOR CONT normal panel, located on the overhead panel,
- A buzzer.
The keypad enables the cabin crew to request access to the cockpit. There are two different access
request types : “Routine” and “Emergency” access request
(The routine code is known by all crew in the airline, the emergency code is known by all flight crew and senior cabin attendants.)

The toggle switch enables the flight crew to lock or unlock the cockpit door, following an access
request, thereby allowing or denying the entry to the cockpit.
The cockpit door control unit is the system controller, in charge of :
- Locking or unlocking the door latches, upon flight crew action.
- Unlocking the door, in case of cockpit decompression (the door then opens towards the cockpit
under differential pressure).
- Indicating system failures of electrical latches and pressure sensors.
- Activating the access request buzzer and turning on the keypad LEDs.
The buzzer sounds in the cockpit for 1 to 9 s to indicate that a routine access request has been
made, or sounds continuously if an emergency access procedure has been initiated.

CENTRAL PEDESTAL COCKPIT DOOR PANEL
The secured cockpit door opening is controlled by a toggle switch, located on the central pedestal.
COCKPIT DOOR toggle switch:

UNLOCK position : This position is used to enable the cabin crewmember to open the door. The switch must be pulled and maintained in the unlock position until the door is pushed open.

NORM positon : All latches are locked, and EMERGENCY access is possible for the cabin crew.

LOCK position : Once the button has been moved to this position, the door is locked ; emergency access, the buzzer, and the keypad are inhibited for a preselected time (5 to 20 min - as defined by the airline).

(Use of the emergency code will unlock the door unless the LOCK position is selected on the control panel.)


I hope this information is useful.

[a210210200]

Also there is a video that describes the system.

https://youtu.be/ROIH3KCEIvs

It is pretty stupidly one sided. Anyone in the cockpit can forever lock out the door with no secure method to override it from the outside.

[Wytnucls]

I don't see any scenario where a captain would reveal his door code to anyone, knowing that it would mean death for all on board.
Your procedure is far too cumbersome when time is of the essence.

[cimmo]

I don't see any scenario where a captain would reveal his door code to anyone, knowing that it would mean death for all on board.
Your procedure is far too cumbersome when time is of the essence.

The codes are not personally assigned. The emergency code is the same for the entire airline and could well be known by 'bad actors' through social engineering methods, etc.

[a210210200]

I don't see any scenario where a captain would reveal his door code to anyone, knowing that it would mean death for all on board.
Your procedure is far too cumbersome when time is of the essence.

He doesn't have to give it up, I doubt they could change the codes constantly. The existing system's only protection against that is that the cockpit can always lock out the outside.
 
The override code being remembered by one person is extremely risky as it is a fixed number a human remembers. He may accidentally give it up or have it stolen. Worse the suicidal person just has to kill or incapacitate the other pilot which could easily occur by surprise when they try to re-enter.

MH370 took hours to crash and is likely some suicide (CVR would be useless, crash in the middle of nowhere, turn off all transponders)
Germanwings people had minutes to unlock the door this is plenty of time to get the crew to use their access card on a door.

Airbus planes have flight control laws that prevent a direct unsafe nosedive and with improved systems that do forward looking terrain avoidance automatically you give your cabin crew plenty of time.

A multi-key system is not that complex it is just a bit slower but that is the point.

[coppice]

Also there is a video that describes the system.

https://youtu.be/ROIH3KCEIvs

It is pretty stupidly one sided. Anyone in the cockpit can forever lock out the door with no secure method to override it from the outside.

If you consider a terrorist taking the flight attendants hostage and torturing them until they open the door, a fit pilot can refuse to allow the door to open. That's what the 30s of beeping is for. Its the pilot's situation evaluation time.

[a210210200]

If you consider a terrorist taking the flight attendants hostage and torturing them until they open the door, a fit pilot can refuse to allow the door to open. That's what the 30s of beeping is for. Its the pilot's situation evaluation time.

I do consider that in my idea. If they attempt that any one cabin crew member could erase their key device rendering the door safe and the terrorists unable to override the door. This action could be done without them noticing as the flight attendants don't actually know the code the devices they hold do. If they erase them the terrorists would not be able to tell this and they could be "forced" to hand over a useless key.

The system requires all the crew members in the cabin to be simultaneously taken hostage and tortured with everyone giving up without erasing their key device covertly.

If anything a terrorist could use human factors to cause the door to open by recording a message with the flight attendants voice that is normal and playing to back through the intercom to request access. Once they do so they gain control of the flight deck and the crew have no method to override the door locking system.

[Wytnucls]

There is no card reader on the door. Codes are memorized.
You are mistaken. Time is limited. A few seconds only. Any Airbus pilot knows how to override control law computers and fly the aircraft in a steep dive.

[a210210200]

There is no card reader on the door. Codes are memorized.
You are mistaken. Time is limited. A few seconds only. Any Airbus pilot knows how to override control law computers and fly the aircraft in a steep dive.

I know there is no card reader I'm proposing a override system.

The Germanwings flight did not nosedive it would take some time to override the computer systems not to mention if it was a terrorist they may want to hit a nearby target and not immediately nose dive. This proposed change would provide people a fighting chance at saving their flight. Suicide is a bit complex and in both this case and MH370 the flights did not immediately nosedive.

A person abusing the door locking system may not even be a pilot so may not know how to override the flight control system. (It could very well be the second person they are now mandating)

[sleemanj]

I guess bus drivers are always just perfectly balanced happy people who would never consider driving off the side of a mountain or bridge, because I don't remember ever seeing a dual control bus with two drivers in the cabin at all times :-/

[Wytnucls]

It takes one second to disable the computers. Your best chance of survival with a suicidal pilot is by letting the other one in again asp, not by pooling multiple security cards.
A 'second person in the cockpit' rule will reduce the threat to a large extent.

[a210210200]

It takes one second to disable the computers. Your best chance of survival with a suicidal pilot is by letting the other one in again asp, not by pooling multiple security cards.
A 'second person in the cockpit' rule will reduce the threat to a large extent.

A pin code that cannot be locked out is a very large security hole a terrorist only needs to get this code by some means (i doubt anyone can remember a constantly changing high security code).

It does not take one second to disable the computers and suicidal people usually want to hid their suicide from being discovered and previous plane crashes where this happened has indicated this.

By your logic if they can throw the plane into such a severe condition in one second then there is nothing you can do as you wouldn't be able to enter the code in any case let alone open the door.

A second person in the cockpit rule does absolutely nothing against a suicidal crew member. The person committing suicide could very well be that second person.

An instant use override code that a pilot remembers is useless too because other crew/pilots know about this system and just have to kill or incapacitate that person inside the cockpit.

Pooling multiple security cards allows people to stop the Germanwings, MH370 type situations and any other copycat that want to hid their suicide attempt.

[cimmo]

A second person in the cockpit rule does absolutely nothing against a suicidal crew member. The person committing suicide could very well be that second person.

And that has happened. http://en.wikipedia.org/wiki/Federal_Express_Flight_705
A cargo aircraft (no pax), but a deadheading pilot went ape-shit with hammers and a spear gun.

The only way to mitigate against flight crew suicide attempts is to remove them entirely. The technology IS already there, the only part of a typical flight that actually requires a human is taxying (assuming no systems failures occur).

BUT - how many of the travelling public would accept being self-loading cargo inside a drone?

[Wytnucls]

It might take three seconds to disable the computers, if you're slow. I said a quick crew re-entry is you best change of survival, not a 100% certainty.
Previous accidents are irrelevant as rogue actions would have been modified to defeat your card pooling.

[Kjelt]

Just add a small toilet to the cockpit, and some ways that the pilots can make their own hot/cold beverages and food,  problem solved.
If you take a step that the cockpit should so extremely be protected as it is at the moment, than there should also never have to be a reason why one of the two pilots have to leave the cockpit in the first place or any other cabin personell have to enter the cockpit.

[cimmo]

Just add a small toilet to the cockpit, and some ways that the pilots can make their own hot/cold beverages and food,  problem solved.

A380 aircraft already have a dedicated flight crew rest area (bunks) and a toilet on their side of the secure door. All they need is a microwave oven? (Or maybe the hosties can give them a meal tray through a slot in their cell door?)
But on smaller aircraft, the weight penalties would be prohibitive.