A330 flight control laws saved Voyager, inquiry finds | Hacker News Reader

A330 flight control laws saved Voyager, inquiry finds

flightglobal.com

219 pointsrwmj177 comments

From the headline, I could not figure out how an A330s flight control system could have any influence on spacecraft launched in 1977. Surely there would be no way to port the code and the storage on the Voyagers is tiny... at least until the V'ger Mk. I upgrade.

That was my first thought too

Incidentally my first thought too.

Voyager is the name RAF use: http://www.raf.mod.uk/equipment/voyager.cfm

The next step up is auto-GCAS. That system, which started going into USAF F-16s in 2014, has already saved four planes and pilots. Here's a video of the cockpit view. The pilot had briefly lost consciousness during a high-G maneuver, and the auto-GCAS system rolled the plane wings-level and pulled it out of a dive and into a mild climb.[1]

Work is going on to develop auto-GCAS for aircraft without the maneuverability of a fighter.

[1] http://aviationweek.com/air-combat-safety/auto-gcas-saves-un...

A similar system is beginning to roll out in case of Cabin depressurization, the plane descends and enters a holding pattern until somebody hopefully gets back from hypoxia (there's a good Smarter Every Day video about this)

The Garmin G1000 "glass cockpit" offers a blue straight-and-level button even for small general aviation planes, such as the Cirrus: if you get disoriented or into an upset, just press it (whether the autopilot is on or off), and the autopilot will level the plane and hold altitude. However, AFAIK it's not an automatic envelope protection, though I'd think that it would be feasible.

http://www.whycirrus.com/advancements/Cirrus-perspective-coc...

"seven dented ceiling panels, 50 damaged in-flight entertainment sockets"

The article doesn't state it, but that's because the passengers, like the co-pilot, fell towards the ceiling of the airplane during this episode. Apparently, the headphone cables are stronger than those sockets.

It's a safety concern that at least 50 passengers didn't have their seat-belts on!

And this is why they tell you to always keep your seat belt fastened when seated, even when the seat belt light is turned off. You never know when a sudden maneuver or severe turbulence might hit.

Is it me or has seat-belt-sign discipline gone out the window?

Over my December travels, dozens of passengers on all 4 segments I flew openly flaunted the seat-belt sign, getting up to go to the bathroom and standing in the aisle waiting for it in full view of flight attendants, who didn't say anything. I broke down and did so myself, as the seat belt sign was on for the vast majority of the flight and I was getting desperate.

In the years prior, I've been sternly commanded to get fuck back to my seat when queueing for the bathroom, even with the seat belt sign off. Never observed anyone out and about while it was on. Maybe the only care in the front of the plane, since you might be preparing to rush the flight deck or something?

Any frequent fliers notice this change?

I've noticed that too. I used to do that myself, until I hit some of the worst turbulence of my life flying in to Denver a couple years ago. Whacked my head pretty hard on main cabin ceiling (the plane dropped ~20ft without warning and I didn't). Ever since then I've worn my seat belt for as much of the flight as possible.

During flight, you can set the belt a bit looser. For cases like this it's more important to keep you in your seat, than to keep you there as tight as possible, which is more important in case of a crash.

"flying in to Denver ..." I live in Denver and I consistently dread flying home because of the horrid turbulence we experience.

I've never noticed it to be otherwise, except during take-off and landing or during severe turbulence. The other exception was the front of the plane for long while after 9/11; maybe that's what you remember.

This is something I've heard and don't recall where, so grain of salt and YMMV, but there are supposedly two modes of seat-belt-sign on: "advisory" and "hard". The latter is for take-off and landing, and very bad weather, the former is "there may be some turbulence, so take care when walking around (and stay seated if you're in doubt)". You can tell the difference by whether the flight attendants are seated.

Well the pilots usually only turn on the seatbelt sign for the higher turbulence times. Maybe they got overzealous to the point where people assume it's being overprotective and meaningless.

I've been on two flights where the pilot announced that he's leaving the seat belt sign on, but if you choose to get up to use the restroom, you're doing it at your own risk.

I don't think he had much of an option since the seat belt sign was on pretty much the whole flight which was 4 hours long.

Not really. My observations go for intra-European flights, though.

You're usually also not yelled at when queuing for the loo, provided the seat-belt sign is off.

What I do notice a lot, though, is passengers that unbuckle half a second after touch down.

To me this seems incredibly stupid.

For starters: it's really dangerous to them and by extension to their fellow passengers and to emphasize the idiocy: They're off the plane exatly zero seconds earlier than when they just stay buckled up until the plane arrives at the gate.

Personally, I just stay buckled up, while sitting. The inconvenience is minor. Especially compared to the inconvenience when your head crashes through the overhead bin, due to sudden turbulences.

I think it's the same mindset of people who wear a seatbelt with the shoulder restraint tucked behind them: "It's uncomfortable! And besides, it only affects me!"

That's great, except that your tubby ass will become a missile if anything happens to this vehicle. Also, planes have a habit of randomly jumping around with no warning because of invisible turbulence.

I haven't noticed any changes. Seat-belt discipline has always been low, IMO. Lots of people failing to buckle-up when the light goes on, or unbuckling the second the plane touches down.

I always leave my belt on when seated. No good reason not to do so. I'll tighten it for take-off and landing, and loosen a bit in-flight.

As for stewards commanding passengers back to their seats, as noted above, it seems to depend on the level of expected turbulence. If it's minor bumps, and the stewards are still serving coffee, they rarely seem to object if the odd passenger goes to the toilet. But, if the stewards are told to buckle-up, they appear to take a more active role in keeping passengers seated.

And all that said, a pilot's proclivity to turning on the seat-belt light seems to vary widely. I was on a United trans-Atlantic flight in 2016 where the light was on for any mild bumps. Then, in January, on an Icelandair flight, the lights never came on, despite a few moderate bumps.

Just to point out - I think you meant 'flouted' not flaunted

My experience in the past year is attendants being much more strict on the "no standing in line for the bathroom" thing.

Honestly, I don't understand how this is supposed to work. If we can't get in line, then we have to watch carefully, and as soon as someone leaves the bathroom, jump up and run down the aisle to it. But everyone else who wants to go is doing the same, which means that the person whose seat is closest to the bathroom wins, and everyone else needs to got back to their seats. So people farther away don't get to go, while those sitting near them also grow increasingly frustrated.

Presumably (given the height lost in the inadvertent dive, and the fact that only one of pilots was returning from the toilet at the time of the incident) this was not during takeoff or landing.

There were only 25 passengers...

The article states there was 198 souls on board

The article is confusingly worded, mentioning 25 passengers and 7 crew in another part... Which are also described as 25% of occupants, but that's not 25% of 198.

Thanks, those figures were confusing me. I wasn't sure if there were 32 or 198 people on board.

Other figures are also surprising:

"a maximum indicated air speed of 358kt (662km/h), or Mach 0.9", while at 30000ft, Mach 0.9 is typically 983.7 km/h(source among others: https://www.globalaircraft.org/converter.htm)

Maybe "indicated" makes a difference, but so wide?

The outside of the airplane has a forward-pointing tube called a pitot tube. As the airplane travels forward, air is compressed into this tube. By measuring the pressure, you can derive the airspeed. However the higher you go, the lower the ambient air pressure is and so the "indicated airspeed" is not at all accurate.

However indicated airspeed is still very useful as it measures the air resistance the aircraft is encountering which determines lift and airframe stresses (which is why the airframe speed limit is in indicated airspeed and not actual airspeed).

Indicated airspeed is not related to ground speed, but indicated airspeed is the important number, as far as keeping the aircraft in the air is concerned.

On the subject of indicated airspeed, does the mach number have the same meaning? That is, if the aircraft had reached an indicated airspeed of Mach 1, would they break the sound barrier and experience a sonic boom?

I think you have some confusion about indicated airspeed - it's used because it provides pilots with predictable information about how the plane will react, it's not indicative of the actual speed of the plane: https://en.wikipedia.org/wiki/Indicated_airspeed

They were truly at 0.9 mach, had they increased speed by 11% they would have broken the sound barrier, well before the indicated air speed would have read a >mach 1 number.

Yeah, this is what threw me:

"“Up to 24% of the aircraft occupants were rendered temporarily unfit for duties following the incident,” the report adds, referring to 25 passengers and seven crew members."

I read that as 'up to 24% of the 25 passengers and seven crew members'. I completely missed the quote at the bottom (beneath the image) that refers to the 198 people. And you're right, the figures don't add up anyway.

souls. Not bodies.

Not sure if you're serious or not, but 'souls' is the term used to refer to everyone onboard a plane (when declaring an emergency, etc)

It was a military plane. It would not be astonishing if it turned out that the number of bodies aboard were significantly greater than the number of souls aboard.

(Actually the way I see it there are never more than zero souls aboard, but I understand it's a metaphor)

It's not a metaphor, it's just jargon. It's how the total number of people on board an aircraft is clearly expressed without the confusion of "I've got 37 people aboard" "Ok... is that 37 including you, or 37 plus the pilot?"

The juxtaposition is a well-known jest:

"Ankh-Morpork! Brawling city of a hundred thousand souls! And, as the Patrician privately observed, ten times that number of actual people."

- Pratchett, Terry (1989), Guards! Guards!, Corgi UK.

I suggest the usage is wry rather than derogatory, unless accompanied by more specific disparagement.

I flew with my final-trimester (ie very visibly) pregnant wife in a small helicopter. The pilot announced the number of souls including the unborn, i was, (and still aren't) sure whether this was just cute for effect, or what he was supposed to do.

Ok, but what do they do for Air Force One? The only souls on that plane when it's flying are likely to be the pilot and copilot.

Same goes for any corporate jets used by corporate executives.

The link I posted is the only good technical summary, but there are plenty of others about the pilot's ongoing military trial, eg: http://www.telegraph.co.uk/news/2017/02/06/bored-raf-pilot-s... 'Bored' RAF pilot sent 187 passengers into a nosedive 'while playing with his camera'

> The link I posted is the only good technical summary

Agreed, except for...

> Its automatic high-speed protection system was triggered 3s later, with a maximum indicated air speed of 358kt (662km/h), or Mach 0.9, recorded.

There is another thread on exactly what you've perceived as an error, because that statement is, in fact, accurate, counterintuitive to a physics education.

Damnit. My initial thought is that I didn't take into account air pressure. Now I feel like an idiot, time to research...

After reading the summary it sounds like a "CAPTAIN HAD A MASSIVE HEART FAILURE AND SLUMPED FORWARD ON THE CONTROLS DO NOT CRASH AIRPLANE FROM CRUISE ALTITUDE IF POSSIBLE" which might sound pretty obvious but, uhh, that's some nice code work. That's why there are two (2) pilots in theory/practice, because human redundancy is a valuable asset.

I can't help but think if there was a video camera in the cockpit it might have looked a lot like that scene in "The Big Lebowski" where he drops his joint between his legs while driving and then loses control and hits a dumpster. Shit tends to domino from time to time lol.

Remember that most of the sources of typical crashes or problems have been eliminated. Which means that accidents happen they're always freak accidents.

Not really, that recent crash in San Francisco had alarms going off like crazy and the idiot pilot still managed to crash the plane. Once you read enough NTSB reports / bulletins about General Aviation accidents (usually only big stuff makes the news) it becomes very clear that accidents happen and bad decisions happen. Like turning off the wrong engine...

Was this the Korean (whichever of the companies) airlines crash? I didn't read up too much into it after the fact.

Taipai, Taiwan. I believe it had trouble in one engine briefly after takeoff, and the pilots tried turning it on and off again. Unfortunately they turned off the still-functioning engine and it plummeted into a river.

You might remember the shot of it flying over a bridge, rolled 90 degrees and so close to the ground that the wing partly sheared off.

You're referring to the Transasia in Taiwan.

GP probably was about the Asiana 214 into SFO, RW 28 L, where the ILS was inoperative, so it was a bog standard visual approach into a nice long runway in beautiful weather in a flawless Boeing 777 that the crew botched. (First fatal crash of a 777 - great plane!)

However, the 777 supports the point made way above: the planes and systems are so good these days that most accidents are freak accidents.

Let's look at 777 hull losses:

* 2008, BA 38 into LHR: weird problem with frozen fuel filter (no fatalities)

* 2011, EgyptAir 667 on the ground in Cairo: fire (no fatalities)

* 2013, Asiana 214 into SFO: inop ILS, suboptimal crew resource management (a few fatalities, one run over by fire truck)

* 2014, MH 370: freak freak freak freaky

* 2014, MH 17: shot down over Ukraine

* 2015, BA 2276 in Las Vegas: uncontained engine failure (no fatalities)

* 2016, Emirates 521 in Dubai: crash on botched go-around (one fatality, fire fighter)

So, I'd say there were some crew problems, some design problems (hopefully fixed), and many really freaky confluences of unfortunate circumstances...

Yeah originally the news cycle had some spin on it - I clearly remember some lines about "Wow check out the heroic actions by the pilot to avoid crashing into any buildings!" and later when the cockpit recorder came out, uhhh, not so heroic. Human, an error...preventable? Up for debate but I like to think a lot of US regulated pilots would be able to handle it appropriately.

Doesn't just happen in general aviation. Turning off the wrong engine brought down TransAsia Airways Flight 235 2 years ago.

The video camera in the cockpit was what got stuck in the lever and caused the problem in the first place.

P.S. That's one of my favourite scenes of any movie ever ️

for reference

https://www.youtube.com/watch?v=SjBBDJ5OiT0

The Register has another take on this, including the court martial results:

https://www.theregister.co.uk/2017/02/07/raf_voyager_zz333_f...

The linked article states that the trial of the pilot is continuing, not that a verdict had been handed down. He is being accused of two counts of perjury and one of making a false record. He has plead not guility to all charges but does admit that a camera did become wedged behind the stick.

Title needs to updated: 1) Published in 2015 2) Clarify that Voyager is military designation for A330

> Clarify that Voyager is military designation for A330

AFAIK, Voyager is only the RAF designation for the A330 MRTT. As far as I'm aware, the other airforces that operate it largely don't have any specific designations.

not sure it's legit for airbus to be declaring a win for their automation. sounds like the copilot dogpaddled back to the cockpit through freefall and batted at his controls from the ceiling until the computer got confused and resumed level flight.

If any safety technology deserves credit here it's seatbelts. From the sound of it, nobody who was belted in was injured.

The computer worked to prevent the aircraft from entering an overspeed condition by pitching up and attempting to recover from the dive even before that dual stick input was an issue. It was intervening 13 seconds into the incident, as the aircraft threatened to exceed safety tolerances. The dual stick input created another issue after that intervention began.

The automation very possibly saved lives here. The overspeed protection is good because had that not happened, there's a real possibility that significant sections of the airplane would have sheared off, or the airplane could have rapidly drifted further out of control as it accelerated quickly through 365 knots indicated. Big, heavy, thrusting things gain airspeed rapidly when you pitch them down 18 degrees at cruise power, and the margin of recoverability is very minimal. There are arguments that humans are unable to prevent some scenarios in that situation because by the time higher-order thinking on decisions has happened, it's too late. See, for example, the surprisingly lengthy duration of time between the incident and setting for idle, which probably should have been among the first things done in response. Brains are slow when things happen fast, and a symphony of alarms and whoops (undoubtedly in progress) does not help.

A Boeing would not have intervened in the situation at all and would have allowed the aircraft to go overspeed, risking serious airframe damage. If you crash dive an airliner at cruising speed, very, very bad things happen. At cruising altitude safety envelopes are very small. The paragraph talking about direct law is, roughly speaking, what would have happened had this been a Boeing aircraft. (This isn't bad, it's just different philosophies of pilot responsibility. I'm not partisan on the difference like some pilots and am willing to acknowledge the benefits of both approaches; this one is an Airbus advantage.)

A Boeing would not have intervened in the situation at all

OTOH it's probably a lot harder to "jam" a camera into the center stick of a Boeing than it is into the side-stick of a Bus.

I could also imagine that a Boeing pilot generally has more respect of the machine (s)he's operating because of the direct control. The overall deadly accident rate in Boeing vs. Airbus, plotted over time, would be interesting.

Both aircraft are so incredibly safe with vanishingly low accident rates, that it'd be nearly impossible to suss out accidents due to the respective designs versus pilot error, weather, carrier procedures etc.

The silly thing is they could combine the fly-by-wire system with the boeing-style control system if they wanted to. There's no reason why not, other than the space in the cockpit I suppose. It's basically just a much bigger joystick, no?

The biggest advantage of the Boeing approach is that the controls are linked; if one moves, so does the other. Mismatched inputs are impossible.

I truly don't understand the Airbus approach... There is no method of resolving conflicts between the sticks that make sense... Sum them? Average them? Take the last seen input? Prefer the left side always?

Not knowing anything about it, it seemed to me from the article that the system takes mismatched input as an indication that the autonomous systems need to be engaged. Though if it subsequently decides not to engage, I'm not sure what you should do...

I don't work in avionics, but in another field with two pilots. Most things are done by exclusive control meaning there is a selector for which station has the flight stick. But for shared control the way it works is the first station that has non-zero inputs takes exclusive control until they have zero inputs for a short period of time. Although in our case, the availability of two sticks is for hardware redundancy rather than pilot redundancy so the Boeing approach seems safer.

Of course there is a system, and it's sophisticated. Averages are taken in case of inputs on both, and there's a priority button to take precedence (so that the other is ignored). There's more to it than that, but of course there's a system and a lot of thought has gone into it.

In the AF 447 case, the left pilot did take priority, but the dude on the right took it back. Had the left one taken it and held it (by keeping the button pressed), the accident might have been avoided. So the system is hardly foolproof, and one can argue about the particular implementation of the interface and the merits vis-a-vis hardware-linked yokes, but any notion that Airbus haven't thought carefully about it is complete bogus.

http://aviation.stackexchange.com/questions/3455/why-is-the-...

I'm not saying it wasn't thought out, I'm saying that no amount of thought could result in a system that made sense in every situation... Having two independent control inputs means there is always room for subtle failure modes (either technical or operator related).

Multi-master is a tricky problem to solve. When it comes to flying a plane, sitting here in my armchair, I think the the simpler solution (linked yokes) is likely the better one.

Fair enough. I tend to agree, in particular as there was not only AF 447, but also the AirAsia from Surabaya to Singapore, Indonesia AirAsia Flight 8501, with basically the same failure mode.

So:

* KISS... but:

* Airbus engineers are certainly aware of it, though... but:

* they have thousands of Airbuses deployed out in the field though with the current tech, so it's unlikely to be changed anytime soon.

Is even more training the answer? Dunno.

My take:

Today's jets are incredibly well designed and safe. If something goes wrong, though, still better to have rather competent crew sitting at the pointy end.

Nope, it wouldn't happen in a Boeing aircraft. This is a well-known Airbus defect that was a contributing factor to the crash of Air France Flight 447.

Boeing uses traditional controls. It's like a race car steering wheel on a big movable stick. It is really easy to see how the control is positioned.

Airbus uses a small joystick off to the side. It is force-based like a Thinkpad pointing stick, so it barely moves when you push on it. It isn't easy to see if the device is being pushed.

Here, a camera got jammed against the joystick. The pilot nearly made things worse by putting the aircraft in "direct law" mode because he couldn't tell that his own control was causing the problem. In the case of Air France Flight 447, the pilot's idiotic control input was not visible to the two other people in the cockpit.

Airbus will obviously brush this one under the carpet as well, because admitting that the side-stick control is hazardous would cause a need for drastic retrofit of all Airbus aircraft cockpits.

https://en.wikipedia.org/wiki/Air_France_Flight_447#Sidestic...

This is the partisanship I'm talking about, for what it's worth.

I've flown an A320 in a full-size simulator and my experience with its sidestick, even in that simulator environment, does not match what you are describing. The sidestick moves quite far and quite noticeably[0], and does not behave like a ThinkPad. The aircraft simply ignores drastic input, which might be what you're thinking of with that assessment?

Anyway, I'd imagine if I were PIC of this flight and my aircraft suddenly pitched down 18 degrees, the sidestick would be the first thing I'd look at in about the first 750 milliseconds. Not sure why that didn't happen here, but I tend not to judge pilots from accident reports, so I have't put a lot of thought into it. I can't imagine a scenario where any camera could conceal itself in that arrangement, unless the A330 has huge voids under the stick that the A320 does not. Even stopping short of judging the PIC, I have a hard time imagining an outcome where this is an Airbus control flaw, no matter the (as one can see, passionate) opinions on sidestick.

[0]: https://www.youtube.com/watch?v=5zBsxJdI5JI

I don't think the sidestick is the problem, it's the lack of feedback and the fact that the system ignores conflicting input.

Boeing undoubtedly does that one aspect correctly: Regardless of the type of stick the two inputs are linked so if the captain is giving strange input it would be <i>immediately</i> obvious to the copilot. There is no reason Airbus couldn't implement the same system on their sidesticks.

The fact that conflicting input causes the system to ignore both seems like downright insanity and based on the assumption of one input being defective, rather than conflict between pilots. A simple fix might be to include a hand detection mechanism and ignore input from the stick that doesn't have a hand present unless it is the only input and is not overridden.

Bear in mind that the AF447 crash was primarily due to a junior officer not knowing basic flight principles. Visibility of the side stick to the other two crew (the captain had come back into the cockpit and was positioned between the first and second officer) is an issue, but I am not sure that central style yokes like Boeings have would have been a huge help to a crew already overloaded with an insurmountable amount of data to resolve.

There have been many cases of pilots turning the yoke the wrong way [1], or shutting down the wrong engine [2] which are levers in full view of both pilots and not getting immediately picked up.

[1] - https://www.youtube.com/watch?v=2nCvO_QlEm8 [2] - https://en.wikipedia.org/wiki/TransAsia_Airways_Flight_235

In the case of AF447, the first officer (Robert) has to constantly ask the second officer (Bonin) what he is doing and why he is climbing, he's clearly worried about air speed (starting at 2:10:16 in [1]. Had the FO had direct control over the input, he could have felt that the SO was pulling back, and push back the column in neutral himself.

In the case of Crossair 498 (your first link), the copilot knew the captain was turning the wrong. Having linked controls, it is surprising he didn't take over. One of the conclusion was that there was a communication problem between the two pilots due to language barrier [2]. The copilot never gave any input to the controls, so the direct link controls were not an issue.

I'm not sure what how TransAsia 235 is linked to the issue discussed here, OP (tropo) didn't say that Boeing's approach prevents all pilot errors, but that mechanically linked controls have the advantage of letting one pilot know exactly what the other is doing, and give him a chance to intervene.

There is no question that computers doing most of the flying have improved reliability tremendously, but misinterpretation between computers and pilot of what the other is doing has been recognised has an issue and is something the aviation industry is focusing on right now.

[1] http://www.popularmechanics.com/flight/a3115/what-really-hap...

[2] https://www.youtube.com/watch?v=BIAujniUuq0&t=42m20s

I cited TransAir because it was a case where the throttle levers were in sight and easy access for both pilots, yet the co-pilot didn't pick that the captain was retarding the wrong throttle.

Not a criticism - I am a former commercial pilot, and I know just how hard identifying the bad engine in an asymmetric situation is - but it is an illustrative case that in a high workload situation, having visible controls that both pilots can see/access is not always as helpful as one would imagine.

> In the case of AF447, the first officer (Robert) has to constantly ask the second officer (Bonin) what he is doing and why he is climbing

The fact that this happens at all makes me think that there could have been a hardware malfunction or that something got wedged forcing the stick back ever so slightly. So FO says "why are you pulling back?" and SO doesn't even respond since his hand isn't on the control.

In this case the Boeing system wouldn't have stepped in, granted. But in this case the Boeing system also wouldn't have let things get so far so fast. It's much, much harder to accidentally jam a big control yoke so far forwards. It would also take more than the weight of a camera to do so.

The title should read "Airbus' automated flight control conflict resolution system saves plane from problem that Airbus' poor cockpit design allowed to happen in the first place" but that's not catchy.

I didn't look at the details, but keep in mind that AF447 lost the airspeed measurement. I'd guess the pilot is probably looking at the instruments, with wrong speed values, instead of the lever that never moves anyway.

Pilot makes a gross error, Airbus software saves the day ... cue comment how this shows Boeing is better.

All modern Boeings (>= B777) are FBW (fly by wire) and have flight envelope protection. A 787 will absolutely not go over-speed: it will automatically throttle back.

Also, Boeings have a traditional yoke. It seems like a lot of this trouble was caused by the fact a sidestick can easily be hit by something on the front of the chair.

Will throttling back help? The plane is pitched down 18 degrees and mach 0.9 KIAS.

Aren't the injuries trivial compared to the large risk of death? If seat belts are to be praised, it would be because they helped the pilot regain control, not for preventing some passenger bruising.

"Modern technology may be capable of reducing crew workload to historic lows"

It's stated as benefit, but is this the reason pilots get bored perhaps?

Exactly. This is why level 2-4 automated cars scare the hell out of me.

The autopilot, carefully designed to handle all situations the engineers have imagined, suddenly throws hands up "you human handle this!". You, having let the car drive itself all the time have 0 hours hands-on driving time. You are now put in a fast-evolving situation too complicated for computers and are expected to do the right thing.

This how AF447 happened.

The commander of AF447 did know exactly the right thing to do, though. (Aside from maybe knocking the copilot out)

Level 3 is already ok. It means the car deals with anything that happens. It's level 2 that is the problem, and guess where most cars are now?

I do not understand, it took only one input to put it in a dive with auto pilot engaged but two inputs to cancel auto pilot to get it out of the dive?

Apparently the pilot's control was disabled by the camera, which, until it was removed, prevented either pilot's control inputs from having the intended effect.

The camera forced one stick forward, the co-pilot pulled the other one back.

Since the two conflicted the computer decided on its own what to do, and didn't listen to either of them.

It looks like the conflicting stick inputs (once the copilot managed to manipulate the controls, from the cockpit ceiling) caused the autopilot to retake control.

It literally said:"FU guys, I'm getting outta here, with or without you" :D .

Controls laws on an Airplane is an extremely tricky subject and there is no real consensus as to how to deal with conflicting inputs.

I have an A320 type so let me try to guess what happened in the A330. The airbus is... different. You can displace the stick 100% in any direction and it wont bank beyond 67 degrees, pitch up more than 30, or pitch down more than 15. It wont overstress because the stick controls G-forces through a closed feedback loop. It also has high-speed protections where it will automatically apply positive G-force to pitch up in order to slow down. The pilot cannot override these protections. You can do whatever you want with the stick and as long as the computers are working and getting good data the aircraft will not stall, overspeed, overstress, or roll upside down. If you get too careless it will even run the engines up to full takeoff thrust and microblog it to you. These protections were working the whole time the captains stick was deflected 100% nose down. The system isn't perfect and it allows some overshoot, as you can see, but at least the protections kept it within 17 degrees nose down and mach 0.9.

Now to the story at hand, the captain probably didn't realize his camera was wedged between the seat's armrest and the control stick as he moved the seat forward. I can only guess that he assumed the strange attitude was the result of a computer malfunction because he considered turning off the computers that provide many of the protections I mentioned. Good thing he didn't. Now the first officer gets into the cockpit and probably tosses a wtf glance at the captain but upon getting one right back he decides to use his own stick. The sticks in the bus aren't mechanically connected but, just like with mechanically connected sticks in antique Boeing aircraft, their force inputs are mathematically summed. Yet unlike mechanically connected sticks, displacement isn't transmitted across the cockpit so the first officer wouldn't be wise to the fact that the captain's stick was full forward. Luckily the bus engineers thought of this. When the first officer pulled his stick back the computer would have noticed both sticks moving and it would have announced "dual input". This isn't a microblog or a gentle woman's voice. It's a pissed off dude trying to talk some sense into you. At that point the captain probably looked at the palms of his hands to make sure they weren't on the stick. He probably showed his palms to the first officer too. At that point they had two heads working on the problem and it wouldn't have taken them too long to find the camera.

Sounds like the engineering moral of the story here is "don't make joystick mounts placed in relation the armrest such that small objects can easily get jammed between them".

It was a Nikon DSLR, hardly hard to see...

> If you get too careless it will even run the engines up to full takeoff thrust and microblog it to you.

What does "microblog" mean in this context? I assume it doesn't mean that the A330 isn't posting about its engine thrust on Twitter. (Yet.)

The thrust FMA (flight mode annunciator) will show "A. FLOOR" alpha floor or "TOGA LK" (takeoff/go-around thrust lock). The former means Fifi just took over and is applying full thrust for an immediate high AoA situation. The latter means the emergency is over but Fifi is so white knuckled and panting that she's ignoring lever position and keeping full thrust. I say microblog because you have to make a conscious effort to read these things. I just got curious and did some googling and it I'm not the only one who can be confused... The aural warning for low speed is the last thing you hear and unless you actually see TOGA LK and turn off autothrust you'll be overspeeding soon. With flaps down (lower max speed) this happens pretty fast. https://news.aviation-safety.net/2013/12/21/loss-of-airspeed...

Your 2 comments above are very insightful! Thanks :)

When thrust is applied by the computer, do the throttle levers move on their own or stay in their original positions ?

thank you, you were far more clear than the article

"...connected sticks in antique Boeing aircraft..."

We saw what you did there.

Generally one pilot would just be working the controls and needs to be able to override the auto-pilot in an emergency very quickly. Then when the co-pilot comes in and pulls his stick back the computer doesn't know which to follow without side stick priority being set (which is normally just equal priority) so it goes back to auto-pilot and pulls out of the dive the captain was ordering with his jammed stick.

The Register article has this:

"Flt Lt Nathan Jones, the co-pilot, suffered a cut to the head, a fractured back, a prolapsed disc and nerve damage, the court martial heard."

From the article: They then set the thrust levers to idle and raised the aircraft’s nose, before selecting take-off and go-around power and regaining straight and level flight at 31,000ft.

Can anyone familiar with these aircraft opine on why the pilot decided to select TOGA in order to complete recovery? They were at perhaps 28,500 feet at the time. Seems like a a panic reaction.

The higher the aircraft gets, the thinner the air, and the more power required to quickly add altitude at that point.

Most aircraft have a slowly stepped climb and descent managed through ATC that gives them plenty of horizontal miles to change their altitude, so they can more gradually adjust in normal flight without having to use max power.

These pilots fell 4,400 feet, I'm sure they wanted to quickly recover to avoid any further problems with other flights in the area.

Not familiar but TOGA is just the aircraft-idiomatic version of "maximum power", no?

Yes, and it wears the engines out much faster than any lower setting would. Grandparent post has a point, though it probably does have to do with recovering as quickly as possible.

That will likely cut down on flight deck videos on youtube.

Thats what came to my mind too. Which is sad. I definitely dont want passengers exposed to more risk, but I'm also against "its policy" kind of rules that squelch people from having fun and exposing more people to aviation.

> with a maximum indicated air speed of 358kt (662km/h), or Mach 0.9, recorded

What? 358 knots is much closer to mach 0.5 in air. 358 meters/second is close... 662 mph is close.

Further confusing numbers:

> “Up to 24% of the aircraft occupants were rendered temporarily unfit for duties following the incident,” the report adds, referring to 25 passengers and seven crew members.

> “Without the excellent technology of the Airbus A330 flight control laws, the outcome could have been very different, with the realistic potential for the loss of the aircraft and 198 of our people,” MAA director general AM Richard Garwood says in his summary of the incident.

24% of 198 is not 25+7 but 47-ish. What am I missing here?

"Up to" ;)

Indicated airspeed is based on the force of the oncoming air, and decreases as air gets less dense. There's some altitude where 358kt indicated is Mach 0.9.

Edit: before I get more replies attempting to lecture me on how wrong I am, please look up the difference between true airspeed (how fast the air is moving past the airplane) and indicated airspeed (a measurement derived from the difference between static and dynamic pressure on the aircraft that only matches how fast the air is moving when you're at sea level).

> There's some altitude where 358kt indicated is Mach 0.9.

Not really: http://www.aerospaceweb.org/question/atmosphere/q0112.shtml

Those tables make no reference to indicated airspeed.

Thanks for the clarification. Is it normal to refer to kts with the assumption this is related to pressure on the airframe and not actual airspeed?

The reference to the 365KIAS rating later in the article provides only a clue IMO.

It literally says "indicated air speed." There's no need for interpretation or assumption.

If I saw a raw airspeed without and qualifier, I'd probably assume it meant indicated speed. But I fly small planes where that's the only airspeed available. If you want true airspeed, you have to take what's indicated and convert manually.

So it does. I still find this disunion of UOM disagreeable, in the way that "in thousandths, take 300 grams of acetaminophen twice daily" is troubling.

I'm not familiar with that one. Does that mean to take 300mg?

I hope so. It sure as hell can't mean 300g, and anything other than mg would be crazy, but I'm not feeling very confident here.

Why? Do you take issue to the fact that scales show you a measurement in kg rather than N despite it varying as you move around the world (and potentially with changes in temperature, depending on the type of scales)? Velocity/mass is far more intuitive than pressure/force even if they don't apply exactly the same in all cases.

It's about what works easiest for the users of the system.

kg/N varies, but by less than your normal margin of error. That's vastly different from deciding to use newtons to weigh "kilograms indicated" on your trip to mars when they give a vastly different number.

My point was that we don't weigh ourself in 'newtons' despite that being what we are actually measuring. We make some reference conversion to a much more intuitive unit, kilograms. We rely on the fact that it's a pretty constant conversion between the two.

Is this really much different than that? I don't think so. The aerodynamics of the plane (stresses on the structure, performance of the aircraft w.r.t. stall, etc.) all remain ~constant for a given IAS which is why it's used. We're just making a dynamic pressure measurement and converting it to a speed in such a way that it factors in all the environmental conditions that influence what we actually care about - how the plane responds in the air.

The N/Kg conversion might be off by a factor of what, 1% in extreme cases (Denver)? Whereas IAS can easily be a factor of two or more different from the plain English sense of "airspeed".

My point is that airspeed is a vector measured relative to something. In this case, it's set to a specific situation (25C/101.3kPa/0% humidity) and then measured relative to the stagnation pressure at that point because then no matter those variables, the plane reacts more or less the same way for the pilot, who is the one who needs to understand what's happening. Your 'plain English' sense of 'airspeed' is pretty irrelevant to the most critical parts of flight - takeoff, landing and not exceeding the plane's design limits.

Moreover, it also means that if you're flying a very basic plane, you can use external stimuli to understand what the other variables are doing and account for them (also noting that IAS converges to the other 'air speeds', within reason, as you approach the ground). You have markers on runways, wind socks, etc. to all get a feel for what your IAS translates to on the ground and thus how much speed you're going to have when you hit the runway. That seems far more useful to me than having some kPa display on the dash.

> Your 'plain English' sense of 'airspeed' is pretty irrelevant to the most critical parts of flight - takeoff, landing and not exceeding the plane's design limits.

I know the pilot needs a measure that behaves like IAS. I just think it's misleading to call the thing we measure "airspeed" when it can be so radically different from, well, airspeed.

> You have markers on runways, wind socks, etc. to all get a feel for what your IAS translates to on the ground and thus how much speed you're going to have when you hit the runway. That seems far more useful to me than having some kPa display on the dash.

I don't understand this argument. Surely if you were flying in a plane that displayed kPa those same markers etc. would give you exactly the same sense for how a given kPa reading translates into speed on the ground. All that would change would be that the conversion factor would be slightly different. Is "110 knots" any more intuitive (to a non-pilot) as a measure of everyday speed on the ground than "20 pascals"?

It depends on the scales one uses. You're right for most bathroom scales, but not for balance-beam scales as one tends to find in physicians' offices; those measure mass and are accurate in a wide variety of accelerated reference frames (and in particular are insensitive to anisotropies in the Earth's gravitational field).

Accurate weight-measuring scales rely on m = F_w/g, where m is mass, F_w is the normal force delivered by the scale's measuring surface to the measured object, and g is almost always g_n := 9.806 m/s^2 per ISO 80000-3:2006 (item 3-9.2) or similar standards. (Tbh the ISO document does not do much more than offer up a defined value.) This relation only holds (and only approximately) when the scale is used as intended by its designer, and that condition picks out a set of preferred (and accelerated) reference frames. A "contact camp" supporter (like Baez[1]) would say that the measurement of weight is accurate in a much wider variety of frames, crucially including in local free fall.

Modern weight-measuring scales will almost always use SI units internally, but most can supply a variety of output units (the one in my bathroom can show kg, stone, lb, Newtons, and the value read from the piezo element package. It sadly has no internal bubble level or equivalent, and no accelerometer, and its software doesn't make use of data from devices within the mobile device it runs on (which could be placed on the scale between my feet). Finally, it was expensive enough to do any or all of the above, so I won't recommend it).

More colloquially:

http://www.livestrong.com/article/343183-the-differences-bet...

[1] http://math.ucr.edu/home/baez/physics/General/Weight/whatIsW... -- and revisiting this wonderful page is the real reason for this reply. :-)

The aircraft has a maximum speed rating, beyond which the structure may fail. That speed rating is based on the aerodynamic forces on the aircraft, which are proportional to the indicated airspeed, not the true airspeed. That's why the instrument panel almost universally shows IAS. That way the pilot doesn't need to perform an altitude-based nonlinear conversion in his head during an emergency to see that he's about to kill everyone on board.

Just so you know the forces are actually proportional to the square of equivalent airspeed which is indicated airspeed adjusted for the compressibility of the air at the sensor. Indicated airspeed is still a better number than true airspeed for approximating the aero forces

So long as we are being pedantic: The sensor just reads dynamic pressure. To get IAS from the pressure signal it is sufficient to solve the equation dynamic_pressure = density * indicated_airspeed^2, where density is taken to be air at a reference temperature at sea level (mumble mumble except for transonic and supersonic conditions mumble). In order to compute true airspeed, you need to measure the absolute pressure and temperature of the air you're traveling through in order to calculate the density.

The aerodynamic forces are proportional to the dynamic pressure, which is the native reading on the sensor. But when you relate dynamic pressure to indicated airspeed, the do-not-exceed airspeed doesn't change, so you can stick a single red line on the IAS gauge that's always valid.

Uh, I think they have a red line on the gauge, anyway. I just saw an unmanned prototype break up in flight partially because of the lack of said red line, so I'm kinda just assuming that passenger aircraft have one.

When it comes to redline, there are some factors which relate to true airspeed, not indicated. Smaller aircraft (maybe larger too, I'm just limiting it to "smaller" due to my own ignorance) at higher altitude tend to be limited by flutter (a situation where positive feedback from movements of the wings or other surfaces shakes the plane apart) which mostly depends on true airspeed. In my plane, for example, never-exceed speed (Vne) is 143kts indicated at sea level, 121kts indicated at 10,000ft, and a mere 73kts indicated at 36,000ft.

The 143kts figure is marked on my airspeed indicator, but above 10,000ft I have to remember to refer to it elsewhere if I want to go fast.

FYI

  dynamic_pressure = 0.5 * ref_density * equivalent_airspeed^2

Its not a function of indicated airspeed. Indicated airspeed needs to be corrected for the compressibility of air to obtain the equivalent airspeed. At low airspeeds/altitudes, the indicated airspeed and equivalent airspeed are very close, so your equation would hold up just fine.

As a result at higher altitudes and faster speeds, the red line on an indicated airspeed gauge would be variable to account for the effects of compressibility.

When coining new terms at my day job (software engineer) I try to avoid terms like "indicated air speed" for the reason that part of the term – "indicated" in this case – is easily ignored by those less familiar with the terminology, because it seems superfluous. (In this case, "indicated" to a layperson simply means "it was shown on a dial". In that interpretation, it carries little information and hence gets ignored.)

We had a similar problem at my day job (a storage company) – there were two kinds of entities, one called a "volume" and one called a "storage volume". The were related (hence the similar names) but not the same thing. Of course, those less familiar with the difference kept dropping "storage" from "storage volume" to cause all sorts of confusion.

My solution? Eradicate "storage volume" from our vocabulary and replace it with the pseudo-acronym "SV", which stood for nothing. Confusion ended.

Indicated airspeed is not a term for laypeople. Its meaning and significance is well understood by every pilot and aero engineer.

Those less familiar with the terminology generally don't fly aeroplanes. Indicated air speed is different from true air speed and ground speed, but this is essential complexity - pilots need to know it.

Indicated air speed is determined by measuring pressure in the pitot tube (https://en.wikipedia.org/wiki/Pitot_tube) and is shown on the air speed indicator, which on an A330 is on the Primary Flight Display (https://en.wikipedia.org/wiki/Primary_flight_display). Important speeds such as stall speed (https://en.wikipedia.org/wiki/Stall_(fluid_mechanics)#Speed) and never exceed speed have constant values of indicated air speed.

True air speed can be calculated if you know the air pressure, which depends on the altitude and outside air temperature. Altimeters work by measuring air pressure.

It's a good idea when reporting something to take into account the readership, and to a lay audience explain things which are counter-intuitive.

That seems sensible, but it's way too late to make the change in aviation. You've got a century or so of tradition behind this terminology. The good news is that if you're in a position to make any use of an "indicated air speed" number, then you'll have been taught what it means early on. It's not obvious for laymen, but it's not intended for laymen either.

As a pilot, you cannot escape knowing this terminology. Knowing how your instruments do their measurements ("indicated vs true air speed", among others) is absolutely integral to the job, if you don't want to fly into a formation of "cumulo-granite" somewhere along the line.

One is what your pitot tube is telling you - which is a combination of altitude, weather conditions, wind, and airspeed.

The other is how much air is flowing over your wings - which is what actually keeps you aloft.

To quote the ace fighter pilot Yogi Berra - "In theory, theory and practice are the same. In practice, they are not".

You cannot escape pressure-altitude. It has way more implications than this. Starting with your ability to get off the ground.

IIRC, true airspeed is not especially useful. Ground speed is important for navigation (although hard to get accurately without GPS) and IAS tells you the forces acting on the aircraft.

"KIAS" is literally "knots indicated air speed"

"KTAS" would be "knots true air speed"

It's no more a clue than "mph" would be a clue for "miles per hour", IMO

Yes, my suggestion is that KIAS is an okay UOM, and knots is inappropriate/confusing.

However, unlike the xkcd strip about HO model trains, I'm not ready to mount a ferocious defense with regard to this thing I just heard about.

That's not correct. At 33,00 ft, Mach 0.9 is about 600Kts, the altitude charts don't go high enough for Mach 0.9 to be 358Kts - by that point yo haven't enough air to transmit sound.

And if you're implying that 358kts indicated could be 600kts actual with the right tailwind - that's true, but it still wouldn't be Mach 0.9, as the speed of sound applies only to airflow over the airplane. No matter the tailwind, the airflow will remain subsonic.

If this weren't the case, passenger liners could go supersonic with a 200kt tailwind all day long...

It has nothing to do with wind. 358kts indicated at 30,000ft translates to about 670kts true airspeed, for example. It's purely a result of how airplanes measure speed.

https://en.m.wikipedia.org/wiki/Indicated_airspeed

Neither is this. An airplane measures indicated airspeed by sampling dynamic pressure. This happens to be useful because it has a direct correlation to various important V-speeds, such as the speed where a wing in a certain configuration generates enough lift for forward flight and so on. This is why an aircraft's V-speeds are given in KIAS. (Put another way, you get the density altitude calculation for free by relying on IAS, as the airplane gets more "inaccurate" with altitude but in actuality "accurate" from the perspective of fluids traveling over surfaces.)

As an airplane gains altitude, IAS dramatically falls versus true airspeed due to this measurement artifact. Complicating this calculation for someone approaching it physically, as you have: by regulation all aircraft calibrate to the same altimeter pressure (29.92 inHg) beyond 18,000 feet. If you think about this physically, that means a whole bunch of airplanes indicate 35,000 feet but in actuality linger around 34,000 or 36,000 or something depending on the actual atmospheric pressure. That also affects how airspeed is calculated, meaning you can't say "well, at 33,000 feet, Mach 0.9 is blah." That computation is a little more nuanced based on the way aircraft sensors are set up and, until computers, required a whiz wheel.

'mikeash is correct, here. You're correct for TAS. IAS is a weird aerospace-specific thing where it's actually helpful to be wrong. I know. To the point of the article, too, the computer worked to avoid exceeding Vne and probably started intervening after passing Vno, which are both figures given in KIAS because both rely on how thick the air is. (Everything in this comment applies to subsonic flight, and the entire calculus changes when you're >=Mach 1.)

Thin and very cold air.

The altitude was 33000 feet (FL330). Assuming a ground temperature of 15 celsius and a drop in temperature of 2 degrees per 1000 feet gives an OAT of -51 celsius. My flight computer converts 358KIAS @ 33000feet @ -51celsius to 620KTAS, which is Mach 0.94.

FL = flight level (hundreds of feet)

KIAS = knots indicated air speed

KTAS = knots true air speed

OAT = outside air temperature

The speed of sound varies with altitude. Nevertheless, at 30,000 feet, Mach 1 is 1,091 km/h, so the original statement is not correct (mach 0.9 at 30,000 feet would be about 982 km/h).

My takeaway/learning is that "knots indicated airspeed" is a measure of pressure due to the aircraft mushing its way through the atmosphere, and is vaguely in proportion to actual_airspeed * altitude, and from my non-pilot's perspective ought to be expressed in bars or torr or something else meant for pressure and not velocity or distance.

The airplane flies based on how much of that mush is doing work on various parts of it, which means "I stay in the air" is a complex calculation of speed and pressure. Factoring in the slowly-decreasing density of that mush to those very important speeds saves calculation time, which is why pilots stick with indicated as the baseline. It's a known-wrong measurement with some valuable uses, and true airspeed and ground speed are usually available in the cockpit in real time. They're just not flown by.

You are not going to like 'density altitude' then, and the terms 'light year' 'parsec' and 'electron volt' will blow your mind.

Despite the efforts of standards bodies to regularize everything, people continue to use measures that match their purpose.

IAS is calculated from the difference between the outside air pressure as measured by a "static" port on the side of the aircraft and the pressure measured by the pitot tube pointed in (hopefully) the direction of travel. It could be measured as pressure, but it is proportional to true airspeed under standard temperatures and pressures.

The short answer is that bus left about a hundred years ago.

See about page 10-24:

https://www.faa.gov/regulations_policies/handbooks_manuals/a...

Indicated airspeed, as sibling comments point out, is not true airspeed. The air is moving at 500 but the stagnation pressure is the same as if it were moving only 300 at sea level so the indicated speed will be 300 +- calibration errors.

358KIAS is in fact (or is close) to the Vne (never exceed) speed of an A330. This is an indicated airspeed limit while mach numbers are based off TAS (True Airspeed).

Here's a link to help explain the differences between IAS/CAS and TAS: https://www.decodedscience.org/airspeed-of-an-aircraft-indic...

"Within 10s of the forward stick input, the A330 had reached a 17˚ nose-down attitude. Its automatic high-speed protection system was triggered 3s later"

What exactly did this 'automatic high-speed protection system ' do?

"As the aircraft pitched down, the aircraft’s captain – who was alone in the cockpit – attempted to disengage the autopilot and pull back on his sidestick"

Surly the autopilot would have disengaged when the pilot moved his seat forward and pushed the sidestick forward at the same time?

"With dual inputs being delivered, the A330’s flight protection system was automatically engaged"

I thought the 'flight protection system' was already engaged. Why would dual imputs trigger the ' flight protection system'

“The initial recovery from the dive was the result of the aircraft’s own protection measures, and not the product of pilot inputs.”

What exactly did the computer do to initiate 'initial recovery'?

I was curious, so I found a picture of an A330-200 cockpit here:

http://www.airplane-pictures.net/photo/251517/cs-tom-tap-por...

I'd like to know what kind of camera is going to fall against the pilot's stick and jam it forward!

Judging by the perspective, the seats are all the way back. When occupied, the end of the armrest should be somewhere close to the sidestick.

Shouldn't there be an override switch to tell the plane to only accept one of the two control inputs, for situations like this where one of the inputs suffers some physical damage or jam? None of the hundreds of cockpit switches does that?

What happens if one pilot dumps their entire cup of coffee onto their controls and it malfunctions causing erroneous input? Is it basically game over?

There is. Google "sidestick priority".

Thanks! That is reassuring to know. Shouldn't they have used it in this case when they knew an input was jammed? Obviously it worked out when the computer decided to ignore them, but just curious what the correct procedure should have been here.

I should note that I'm not an expert on this subject.

According to the below, Airbus cockpit sidesticks have a red button on them. Pressing it disengages the autopilot if it's engaged, which is probably the more normal use. Pressing it when the autopilot is already disengaged engages sidestick priority for as long as it's held down. It latches if held continuously for 40 seconds.

http://aviation.stackexchange.com/questions/3455/why-is-the-...

If they were on the ceiling perhaps it could be difficult to hold the button down continuously for 40 seconds.

> “With his feet on the flight deck roof, the co-pilot reached down and attempted to disengage the autopilot by pulling back on his sidestick,”

In this case I don't think they really knew that the issue was the jammed stick before the co-pilot pulling back on his stick gave the flight computer priority. It's hard to really say from the information given exactly when they discovered the camera was jammed and removed it vs when the plane was getting itself back under control.

They also said the captain was pulling back on the stick as well.. or at least ATTEMPTING to. Maybe they're indicating that the stuck camera (which seems to have come unstuck before recovery was complete?) prevented him from doing so.

It would be really weird for both pilots pulling back on the stick to result in a dual input error situation.

Not that weird I think the net force on the Captain's stick was probably still forward with the camera jammed there with him trying to pull back.

Does anyone know how often airliner flight controls get drenched in coffee, and how well they resist it? You never hear about it happening, and there are enough planes in the sky that things often go wrong in much less obvious ways.

On most planes, from Boeings to Cessnas but not Airbuses, the two sets of controls are linked, so that if you move the yoke (pitch/roll) or rudder pedals (yaw) in one set they move in the other set. This means that one pilot knows what the other is doing. Airbuses average the two inputs by default, though either pilot can take control.

SPOILER ALERT:

A coffee spill was the cause of the plane crash in the movie Fate is the Hunter (1964), so I assume the risk is well-known.

Damn.

This reminds me a lot of a fantastic podcast episode on the pros and cons of automation: http://99percentinvisible.org/episode/children-of-the-magent...

What this proves is that no matter how much you test and plan and design for things people can always find some way to screw things up you never imagined. I always keep that in mind when writing software for people.

> "Up to 24% of the aircraft occupants were rendered temporarily unfit for duties following the incident"

Gotta love the officialese for 'people puked everywhere'....

Or flung into the ceiling headfirst at 0.5g and then back to the floor at 2g. Presumably that could cause injuries other than motion sickness.

Indeed. From the Telegraph article linked in another comment:

> Flt Lt Nathan Jones, the co-pilot, suffered a cut to the head, a fractured back, a prolapsed disc and nerve damage.

> The court heard 14 passengers were so badly hurt they were unable to fly back to the UK.

PPrune discussion on the issue, after the cause was found to be the stuck camera:

http://www.pprune.org/military-aviation/533921-voyager-plumm...

Surely this can't be right:

>Its automatic high-speed protection system was triggered 3s later, with a maximum indicated air speed of 358kt (662km/h), or Mach 0.9, recorded.

Wikipedia says Mach 1 at sea level is 1225kph and 1091kph at 30,000ft. Not sure what temperature they assume though.

Indicated airspeed is significantly lower than true airspeed at altitude.

Indicated airspeed measures the dynamic pressure exerted on the aircraft by the motion of the surrounding fluid, not the velocity relative to the ground. Airspeed indicators are calibrated at sea level so you need more information in order to get the calibrated airspeed for your altitude and you still need more data + error correction to turn that into true airspeed, which is the actual velocity of the plane relative to the air.

Why was captain playing around with his camera when you are in charge of 200 lives?

Autopilot.

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