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A330 flight control laws saved Voyager, inquiry finds

flightglobal.com

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Re: A330 flight control laws saved Voyager, inquiry finds

#131

Post by refurb »

mseebach wrote: post #111
closeparen wrote: post #83

Earlier quoted context omitted.

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…

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.

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.

Re: A330 flight control laws saved Voyager, inquiry finds

#132

Post by alistairSH »

closeparen wrote: post #83
kristianp wrote: post #20

Earlier quoted context omitted.

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

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…

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.

Re: A330 flight control laws saved Voyager, inquiry finds

#133

Post by sizzzzlerz »

RachelF wrote: post #87

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.

Re: A330 flight control laws saved Voyager, inquiry finds

#134

Post by FabHK »

Animats wrote: post #88

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…

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...

Re: A330 flight control laws saved Voyager, inquiry finds

#135

Post by illys »

Pxtl wrote: post #59
JBReefer wrote: post #48

Earlier quoted context omitted.

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.

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?

Re: A330 flight control laws saved Voyager, inquiry finds

#136

Post by DonaldFisk »

cypherpunks01 wrote: post #29

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?

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.

Re: A330 flight control laws saved Voyager, inquiry finds

#137

Post by Xixi »

jsmthrowaway wrote: post #35
awinter-py wrote: post #27

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 oversp…

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.

Re: A330 flight control laws saved Voyager, inquiry finds

#138

Post by mikeash »

colanderman wrote: post #69
mikeash wrote: post #18

Earlier quoted context omitted.

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.

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 ignore…

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.

Re: A330 flight control laws saved Voyager, inquiry finds

#139

Post by FabHK »

ldp01 wrote: post #119
wapz wrote: post #86

Earlier quoted context omitted.

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...

Re: A330 flight control laws saved Voyager, inquiry finds

#140

Post by knute »

illys wrote: post #135
Pxtl wrote: post #59

Earlier quoted context omitted.

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.

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).

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