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Comment by HPsquared | Hacker News Reader

Unlike trains, there isn't one action that is basically always safe (stop the train). A dead man switch activating at the wrong time, could itself cause an accident.

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That’s true, but there are plenty of other options. For example, a dead-man switch could:

Send an alert via transponders that it has been activated.

Maintain level flight but avoid terrain. (After a waiting period in which a pilot can deactivate this feature.) Or descend to a safe altitude if cabin pressure is lost.

Activate a mode in which the plane could be remotely flown or directed to land itself.

Alert flight crew that the pilots are incapacitated.

Or the most basic: make some noise to wake up the pilots.

> Maintain level flight but avoid terrain

Your other ideas are good. But this could kill people if it misfires and takes the plane off course and too far from an airfield.

Not having anyone flying the plane when it is on manual control can also kill people...

> Not having anyone flying the plane when it is on manual control can also kill people

Not as quickly. Routes are programmed into an airliner before takeoff. Those routes are planned with emergency landing in mind. Left to its own devices, a plane flying its flight path is safer than one simply holding FL (while avoiding terrain).

>That’s true, but there are plenty of other options.

Well we can't settle it in the comments, nor should we. So which of those options can successfully survive a detailed engineering review on its merits?

I recall reading that certain aircraft manufacturers do offer more robust security features if the airlines are willing to pay for them. I don't have a link or source handy, but it's entirely possible that these features have been discussed, but through the lens of how much more would it cost to implement them.

Garmin has a system that can notify ATC of an emergency, choose an airport, fly there, and land the plane, autonomously.

https://www.planeandpilotmag.com/article/garmin-autoland-thi...

There are fighter jets that will take over for an incapacitated pilot. I think it just goes to straight and level.

The existing action is to maintain current settings. A flight in Australia flew across the continent that way, after (theory says) somehow depressurizing during takeoff so everyone passed out.

https://en.wikipedia.org/wiki/2000_Australia_Beechcraft_King...

IMO that story shows that unless you do the remote control option (which I see as unlikely) it doesn't matter what happens...what can anyone outside the plane do except crash it earlier?

The “descend to a safe altitude if cabin pressure is lost” option may have had a chance of saving those lives.

Automatic landing is doable these days.

It doesn't have to stop the plane, it could just trigger a cockpit alarm.

Or alert air traffic control, and maybe they can send an alert into the cockpit. But there must be a way to raise an alarm.

My guess is basically nobody cares that much about this rare condition. It's much more likely the pilots are incapacitated rather than asleep, in which case the alarm is pointless.

But I guess it's not that rare:

  - https://www.newsweek.com/pilots-boeing-737-both-doze-off-overshoot-airport-two-hour-flight-1735435
  - https://jalopnik.com/tale-of-both-pilots-sleeping-during-flight-reminds-us-t-1849014190
  - https://www.cnn.com/travel/article/pilots-sleep-cockpit-airline-safety/index.html
  - https://www.bbc.com/news/uk-24296544
  - https://www.cbsnews.com/news/both-pilots-fall-asleep-during-british-airbus-flight-incident-report-reveals/
  - https://www.aero-news.net/index.cfm?do=main.textpost&id=A9AAFE58-18F4-40B5-B59A-EBE316BBE878
  - https://content.time.com/time/nation/article/0,8599,1932040,00.html

Some planes can land themselves now:

https://discover.garmin.com/en-US/autonomi/#autoland

Autopilot and autoland have been around for a while, but they still need to be set up by the pilot, only operate under certain conditions, and autoland in particular only works at some airports. This is probably not a solution, not for quite a while at least.

The Garmin autoland can automatically activate, determine which airport to land at communicate on ATC frequency to say it is going to land at X airport.

Each pilot can have a button they must always press, if both are released loud tritones alarms and flashing will fill the cockpit, something no one can sleep to.

A proper deadman's switch can't just be a button - you could weight it down, or just fall asleep on top of it. Trains commonly use a pedal you have to hold down halfway. Not sure this is really the best idea though, as pilots typically need both hands (and usually feet) free to actually, you know, control the plane.

A button press could be required, though.

If the pilots are controlling the plane, they are doing detectable actions and pre-empting the dead person switch.

That's not impossible, but the pilots' limbs are already largely "spoken for" by other controls and tasks, so it would be a harsh tradeoff.

If other controls are being actively engaged by the pilot, the need for the button press would be delayed only until there's some continuous period of non-engagement.

Exactly - something like positive activation every minute of some control or another or it starts hooting.

Well... You can. Sleep deprivation is one hell of a drug. After ~23h on a plane without sleep, I slept through a fire alarm at a hotel. It's unlikely that both pilots and other staff would ignore it, but "no one can sleep to" threshold is not that low.

Have the alarm go off in the cabin as well.

Sorry but this a bit ill-informed.

First off, you cannot just put an alarm on everything. The sonic experience inside a cockpit is very carefully designed to give pilots the correct information at the correct time. False alarms are not only not appreciated, they are actively dangerous. If a flight experiencing an emergency situation, a blaring alarm that is incorrectly going off can prevent pilots from getting timely information.

Airbus have side-sticks (like a game controller), not yokes and you really shouldn’t be inputting on them unless you’re hand flying for whatever reason.

In all two-pilot aircraft (all commercial jet aircraft), there are two separate roles that each one assumes: Pilot Monitoring (PM) and Pilot Flying (PF). The PM’s job is usually to run checklists, communicate/operate the radio, check various indicators, and support the PF to fly the aircraft. The captain and first officer swap between these roles en route. The PM should NOT be inputting controls unless there is a good reason to do so, but for safety/redundancy, one side’s controls are never disabled unless a lockout/override is active.

Most airlines have a policy to cruise with the autopilot on, which keeps the aircraft on its plotted course at it’s cleared altitude. The time where “flying” comes into play most often is during takeoff and using various levels of ILS from just indications of glide slope to a full autoland.

While not fantastic, a cruising airbus will keep its current course and stay airborne if the pilots snooze off.

Charlie Victor Romeo was a very interesting watch for that cockpit fly-on-a-wall experience

That doesn't work at all. There are often times like takeoff, landing, dealing with adverse weather events, re-routing, mechanical failure, etc where they're going through a detailed checklist. The last thing you want is some random device that takes attention away from them dealing with a serious problem.

Simple, cut the engines. /s

Do a barrel roll :)

Another of seemingly infinite reasons why trains > planes.

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