SFO near miss might have triggered aviation disaster • Hacker News Board

Re: SFO near miss might have triggered aviation disaster

#381

Post by cmurf » Tue, Jul 11, 2017, 6:01 PM UTC

phdp wrote: post #321

wfunction wrote: post #260

Earlier quoted context omitted.

Thanks for the detailed response. > Automatic landing systems rely on ground support by way of microwave signals from transmitters installed near autoland-capable runways. There's no general position information, and the airborne part of the system can't operate independently of the part on the ground. Yes, I understand the landing portion has other kinds of support. However, I don't understand how it can not have th…

> OK, so I don't have much of an expectation for older plane models, but my interpretation of the above is that in newer models, autopilot need not disengage before landing and require manual intervention in order to align the plane with the correct track (barring bad weather or other unusual situations like bird collisions, etc.). What is your definition of manual intervention? Pilots get updated instructions from t…

>The tone of many comments here (yours too) call out people who actually know how the system works and question them.

Lack of enough common frame of reference that the ability to communicate is almost totally inhibited from the word go. It reminds me of the Feynman magnets youtube video. The interviewer asks Feynman to explain the attraction repulsion sensation and Feynman admits any correct answer the interviewer will not understand because he doesn't understand any of the basic prerequisites of having a conversation; and any answer he gives the interviewer would understand is cheating him out of the correct answer.

Re: SFO near miss might have triggered aviation disaster

#382

Post by [deleted] » Tue, Jul 11, 2017, 6:04 PM UTC

hueving wrote: post #188

lucb1e wrote: post #159

Earlier quoted context omitted.

> WTF? Looking forward to reading the investigation results. I'm not an expert, but given what you said, I suppose it'll just end up equating to "Human error. Happens."

I suggest you read ntsb investigations of some major commercial aviation events like this. It is never just "human error. Happens." They are always full of excellent recommendations, points of failure, etc.

[deleted]

Re: SFO near miss might have triggered aviation disaster

#383

Post by thekevan » Tue, Jul 11, 2017, 6:14 PM UTC

cyberferret wrote: post #33

wfunction wrote: post #21

Earlier quoted context omitted.

Why in the world is this even a problem? Shouldn't what's a taxiway and what's not be indicated on maps or diagrams or something that pilots can see?

Because the pilot is almost never looking at a map on final approach. He is looking out the window, and in the dawn/dusk light, or with a setting sun in the background or inclement weather etc., a taxiway can look exactly like a runway. Don't forget that almost all taxiways run parallel to the runway, for about the same length. (NB: I used to be a commercial pilot.) In most airports I flew into, the surface material…

It seems like an easy problem to solve. Line the taxiway with red/blue/green or whatever color is appropriate lights.

Re: SFO near miss might have triggered aviation disaster

#384

Post by Karunamon » Tue, Jul 11, 2017, 6:14 PM UTC

anovikov wrote: post #212

ddeck wrote: post #14

Attempts to take off from or land on taxiways are alarmingly common, including those by Harrison Ford: Harrison Ford won't face disciplinary action for landing on a taxiway at John Wayne Airport [1] Serious incident: Finnair A340 attempts takeoff from Hong Kong taxiway [2] HK Airlines 737 tries to take off from taxiway [3] Passenger plane lands on the TAXIWAY instead of runway in fourth incident of its kind at Seattl…

This is facilitated by the fact that in some airports, taxiways and runways are similar and sometimes even used interchangeably (!), i.e. a runway may be remarked as taxiway and vice versa. So it's not 'how can he be so dumb' moment, in some case you have no way to tell the difference unless you just know.

Yeowch. I was about ready to make a comment about how the airport/approach plates should make something like this impossible, but then I looked up the diagram for SEA:

https://flightaware.com/resources/airport/SEA/APD/AIRPORT+DI...

Basically, you've got a runway, the taxiway of the same length as the runway!, and then two longer runways from left to right. I totally see how someone could make this mistake in bad lighting or weather!

Re: SFO near miss might have triggered aviation disaster

#385

Post by anigbrowl » Tue, Jul 11, 2017, 6:16 PM UTC

mikeash wrote: post #354

anigbrowl wrote: post #160

Earlier quoted context omitted.

Comment like that would put me off hiring you for any sort of mission- or safety-critical project. The approach for Asiana 214 looked fine until it wasn't; that was less than 4 years ago. Maybe you should stare at the video of that crash for a while and consider the large consequences that can ensue from a small error of judgement made a little too late.

I would say that the approach for Asiana 214 looked bad from the moment it started, as the pilot felt uncomfortable performing a visual approach. Something has gone terribly wrong with training standards if a qualified airline pilot feels uncomfortable performing a visual approach in good weather into an airport with no tricky features. Asiana wasn't a small error of judgment, it was a fundamental failure of training…

That's the systemic problem that led to the error; I worded it poorly but the 'small error' I'm referring to is how the pilot came in just a little too slow and low. It's easy to think of even worse things a pilot might do when panicking, eg breaking off the approach only to stall and land on the tail, for example.

What I'm getting at is that a small error can have big consequences, and that this near-miss last week by the Air Canada plane is not something that should be dismissed as a non-story just because it was spotted and rectified in time. A collision avoided at the last minute is still indicative of a problem. If the Asiana pilot had stuck the landing that day but still felt uncomfortable, their training and operation culture at that firm would still have been problematic, they would just have gotten away with it for a little longer.

Re: SFO near miss might have triggered aviation disaster

#386

Post by Aloha » Tue, Jul 11, 2017, 6:19 PM UTC

tialaramex wrote: post #218

Aloha wrote: post #70

Earlier quoted context omitted.

There is a very good technical reason we still use AM. AM is not prone to capture effect, wherein the loudest signal captures the receiver. With AM, you can hear multiple people talking on top of each other at the same time. https://en.wikipedia.org/wiki/Capture_effect For uncontrolled radio situations where you have a number of unknown people who need to access a radio channel, neither digital nor encryption bring a…

Mmm. Here's the thing, I think we heard a lot of the same arguments before DSC took off for marine radio. They too have uncontrolled radio, a large number of unknown people who need to communicate with whoever happens to be nearby, they have more powerful transmitters owned by governments that "need" to shout down less powerful ones on transport vessels occasionally. Now, maritime radio IS a different environment. I'…

I believe there are significant technical advantages to AM for airband - I also believe that marine radio is less likely to need those advantages, so narrowband digital is more workable there.

Re: SFO near miss might have triggered aviation disaster

#387

Post by Aloha » Tue, Jul 11, 2017, 6:26 PM UTC

mikeash wrote: post #346

adrianN wrote: post #274

Earlier quoted context omitted.

Digital only require better signal if you want high data rates. With analog signal the human has to do the error correction, i.e. extract the signal from the snowy picture. Digital signals can use error correcting codes to get the same result. The more bits you have for error correction, the better your recovery can be.

I hate aircraft radios. I'm sure the guys in big planes have better equipment and don't suffer from this as much, but when I fly small planes, it's a complete mess of wildly different volume levels (it's fun to turn up the volume to hear a quiet person, then get blasted by the next transmission), interference, and irrelevant transmissions from a hundred miles away. Don't get me wrong, they get the job done and any ch…

This is a lack of AGC (automatic gain control) - usually even on the (shortwave and Ham) radios I've seen it on, its switchable, otherwise (in certain conditions, like rapid fading) you can end up with gain pumping, which can sound like the audio is surging.

What it normally does is reduce gain on high strength signals, and increases it on weak ones to give a constant volume level.

I'm honestly surprised the radios in general aviation craft are not so equipped, as its generally a standard part of most AM radios.

Re: SFO near miss might have triggered aviation disaster

#388

Post by [deleted] » Tue, Jul 11, 2017, 6:34 PM UTC

throwanem wrote: post #248

wfunction wrote: post #227

Earlier quoted context omitted.

Okay so let me get this straight: you're telling me that passenger airplanes currently fly by dead reckoning or stellar navigation or ground-based triangulation or something else? When a pilot doesn't know where he is, he doesn't have any kind of certified GPS-based system handy to tell him? And moreover, even beyond GPS: how the hell can a plane's navigation system be capable of (and certified for!) landing the mons…

Automatic landing systems rely on ground support by way of microwave signals from transmitters installed near autoland-capable runways. There's no general position information, and the airborne part of the system can't operate independently of the part on the ground. Civilian GPS signals are limited in terms of position accuracy, too. I believe the CEP is ten meters. That's not bad, but it's not good enough to land a…

[deleted]

Re: SFO near miss might have triggered aviation disaster

#389

Post by avh02 » Tue, Jul 11, 2017, 6:35 PM UTC

khazhoux wrote: post #379

theGimp wrote: post #114

Earlier quoted context omitted.

Good observation. If you're wrong, you suffer a brief moment of embarrassment. If you're right, you might prevent a disaster. Speaking up is a no-brainer.

I wonder how many people have died throughout history due to embarrassment, or (similarly) going against your instinct. The number exists but is unavailable to us. - Not having that dark mole near your privates checked out. - Not wanting to turn the car around. - Not walking away when those shady guys walked in. ...

Korean airlines decades ago had a huge issue with copilots not speaking up to captains when concerned. While not embarrassment - there was a lack of speaking up. IIRC they forced cultural change in order to make it less of an issue.

edit: not speaking up

Re: SFO near miss might have triggered aviation disaster

#390

Post by mikeash » Tue, Jul 11, 2017, 6:35 PM UTC

anigbrowl wrote: post #385

mikeash wrote: post #354

Earlier quoted context omitted.

I would say that the approach for Asiana 214 looked bad from the moment it started, as the pilot felt uncomfortable performing a visual approach. Something has gone terribly wrong with training standards if a qualified airline pilot feels uncomfortable performing a visual approach in good weather into an airport with no tricky features. Asiana wasn't a small error of judgment, it was a fundamental failure of training…

That's the systemic problem that led to the error; I worded it poorly but the 'small error' I'm referring to is how the pilot came in just a little too slow and low. It's easy to think of even worse things a pilot might do when panicking, eg breaking off the approach only to stall and land on the tail, for example. What I'm getting at is that a small error can have big consequences, and that this near-miss last week…

I see what you mean, and I agree. I'm sure the Asiana pilot (and many of his colleagues) had lots of uncomfortable but successful visual approaches before that. This event should definitely be investigated to identify any improvements that could be made. The tone of reporting seems to be going well beyond the severity of what actually happened, but it's not nothing.