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SFO near miss might have triggered aviation disaster

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Re: SFO near miss might have triggered aviation disaster

#131

Post by djsumdog »

CaliforniaKarl wrote: post #122
CaliforniaKarl wrote: post #81

Earlier quoted context omitted.

I'm not a pilot, or real-world ATC, but I was one a _virtual_ air traffic controller, on VATSIM[1]. I was a member of the virtual Indianapolis ARTCC[2], and have worked positions from Dispatch up to & including Center. Listening to the LiveATC clip, the important bit is the phrase "visual 28 right", meaning the Air Canada pilot had been assigned a visual approach to runway 28 Right. The clip sounds like it's from Tow…

So, I should clarify something: A visual approach is pretty simple from the controller's point of view ; it's more work for the pilot. But, the pilot is always the one in command of the plane: If the pilot is unwilling to accept a particular approach, they just need to say so. It may lead to delays, but controllers will accommodate. I originally said that the pilot had been assigned a visual approach to runway 28 Rig…

Wow, that's a lot of detail and analysis. That does make a lot of sense. I know it will be a while for the FAA report to come out, but if it does turn out to be what you've stated, you can totally say you called it.

Re: SFO near miss might have triggered aviation disaster

#132

Post by dx034 »

csours wrote: post #25
FiloSottile wrote: post #4

I am just a passenger, but this looks very over-blown. A pilot aligned with the taxiway, that's bad. But no pilot would ever land on a runway (or taxiway) with 3 planes on it. Just search the Aviation Herald for "runway incursion". And indeed, he spotted them, communicated, went around. Aviation safety margins are so wide that this does not qualify as a near-miss.

> Aviation safety margins are so wide that this does not qualify as a near-miss. I think you have this kind of backwards here. If you were going in for an amputation, and they only prepped the wrong leg, would that not be a near miss? Rare incidents are hard to reason about and measure because they are so rare; but there are things that lead up to rare events - like being on approach to the wrong runway, that are les…

Tenerife was very different. Here, the aircraft were at the beginning of the runway and clearly visible. In Tenerife, aircraft were at different part of the runway and couldn't see each other until it was too late. That's not comparable.

We know from the recording that the pilot saw planes on the taxiway and asked the tower about it. He would've never landed there after the tower confirmed that the runway should be empty.

Re: SFO near miss might have triggered aviation disaster

#133

Post by CaliforniaKarl »

kobeya wrote: post #49
FiloSottile wrote: post #4

I am just a passenger, but this looks very over-blown. A pilot aligned with the taxiway, that's bad. But no pilot would ever land on a runway (or taxiway) with 3 planes on it. Just search the Aviation Herald for "runway incursion". And indeed, he spotted them, communicated, went around. Aviation safety margins are so wide that this does not qualify as a near-miss.

What if the airport was fogged out and the Air Canada pilot was doing a instrument landing?

Then this specific type of incident would likely not have happened.

The pilot here was flying visually (which I expect either means a visual approach, or else the LDA PRM Runway 28 Right approach).

If the airport was fogged out, the pilot would be on an ILS or RNAV (area navigation) approach. The former uses ground-based signals to provide precise lateral and vertical navigation; the latter uses either GPS or multiple ground-based aids to accomplish the same thing.

The downside to ILS, RNAV, etc., is that you can't fit planes as close together while still being safe. That's why you get delays when major airports have reduced visibility: The flight scheduled are "tuned" for maximum planes per runway per minute, which is only possible when skies are clear and winds are (relatively) calm, so that you can use visual approaches.

Re: SFO near miss might have triggered aviation disaster

#134

Post by dx034 »

exDM69 wrote: post #46
FiloSottile wrote: post #4

I am just a passenger, but this looks very over-blown. A pilot aligned with the taxiway, that's bad. But no pilot would ever land on a runway (or taxiway) with 3 planes on it. Just search the Aviation Herald for "runway incursion". And indeed, he spotted them, communicated, went around. Aviation safety margins are so wide that this does not qualify as a near-miss.

Assuming the liveatc audio in the article has not been edited, it sounds like there's about 10 seconds between ATC giving go around and the United pilot saying they flew right over. With instructions given to Air Canada in between so it might have been seconds earlier. Based on that, it was seconds away from a collision. It seems like a near miss when considering aviation safety margins.

I would assume it was edited. He only joins the frequency about 30 seconds before it happens. That means tower only took control once he was 60 seconds before landing. I don't know the procedures at SFO but that seems too short.

Re: SFO near miss might have triggered aviation disaster

#135

Post by exDM69 »

CaliforniaKarl wrote: post #129
exDM69 wrote: post #46

Earlier quoted context omitted.

Assuming the liveatc audio in the article has not been edited, it sounds like there's about 10 seconds between ATC giving go around and the United pilot saying they flew right over. With instructions given to Air Canada in between so it might have been seconds earlier. Based on that, it was seconds away from a collision. It seems like a near miss when considering aviation safety margins.

What's missing is, when (relative to radio traffic) did the pilot begin the go-around maneuver. Did they begin doing so before being told to go around, or did they only start to do so after?

If the pilot initiates a go around they need to announce it to the ATC. It is usually a drastic full power pull up that will certainly disrupt nearby air traffic.

So the pilot probably did not start the go around before being told so.

Re: SFO near miss might have triggered aviation disaster

#136

Post by Aloha »

lb1lf wrote: post #99
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…

-Agreed, intelligibility is pretty good. I've been into amateur radio for ages, presumably that has trained my ear. I routinely copy voice signals which are just a garbled gibberish to innocent bystanders. (Same obviously goes for ATCs and pilots to an even larger degree, being exposed to comms several hours a day)

Hey There OM :-)

Yeah, Even with P25 - the same skills apply, but instead of pulling it out of noise, you're relying on your skills of interpolation to suck it out of the noise. Still it's a neat parlor trick :-D

73's

Re: SFO near miss might have triggered aviation disaster

#137

Post by idlewords »

justinjlynn wrote: post #124
acchow wrote: post #103

Earlier quoted context omitted.

> It is a very Silicon Valley thing to assume that everyone else is an idiot and needs to be disrupted, with not a thought given as to why things are the way they are. This kind of thinking has also lead to a ton of success in Silicon Valley. See Tesla for example.

A broken clock is correct at least once a day.

That used to be true (twice a day, even), but now it just flashes 12:00, or the screen is dead.

Re: SFO near miss might have triggered aviation disaster

#138

Post by CaliforniaKarl »

djsumdog wrote: post #131
CaliforniaKarl wrote: post #122

Earlier quoted context omitted.

So, I should clarify something: A visual approach is pretty simple from the controller's point of view ; it's more work for the pilot. But, the pilot is always the one in command of the plane: If the pilot is unwilling to accept a particular approach, they just need to say so. It may lead to delays, but controllers will accommodate. I originally said that the pilot had been assigned a visual approach to runway 28 Rig…

Wow, that's a lot of detail and analysis. That does make a lot of sense. I know it will be a while for the FAA report to come out, but if it does turn out to be what you've stated, you can totally say you called it.

Again, virtual air traffic controller!

I think many of the readers here would be interested in virtual ATC, as many parts of the brain: Keeping many things in order, looking multiple steps ahead at what's going to happen (it takes time for a plane to turn), and communicating with your "customers".

The only downside is, you shouldn't sign in to control when you're on call 8-)

Re: SFO near miss might have triggered aviation disaster

#139

Post by konschubert »

tmsh wrote: post #92

The moral of this story for me is: be that "another pilot." To be clear, "another pilot" of another aircraft. Not as clear as it could be just like the title of this article is ambiguous. The moral of this story for me is: call out immediately if you see something off. He's the real hero. Even if the ATC controller immediately saw the plane being misaligned at the same time - that feedback confirming another set of e…

The moral might also be that automatic guided landing approaches should be mandatory whenever they are available.

Re: SFO near miss might have triggered aviation disaster

#140

Post by cyberferret »

BinaryIdiot wrote: post #117
cyberferret wrote: post #45

Earlier quoted context omitted.

They do. They have different lighting systems/colours etc. to differentiate them. Taxiways generally have green lights along the centerline to guide aircraft rolling on the ground, but runways usually have white (bright) lights along the edges . There are times when even THAT causes confusion, because sometimes the taxiway centreline lights can look like the edge lights of the runway - especially if the light is refr…

Perhaps this is a dumb question but is there any reason why the taxiway doesn't have HUGE red Xs going down it and the runway with HUGE green arrow going down? Sorta like what they do on bridges where the lanes can shift to allow more cares to travel in one direction but more obvious? They could even angle them so the planes on the ground see them differently or not at all.

Red 'X's on a runway usually denote an inactive or out of service runway.

They ARE actually quite different in terms of lighting, width etc. and 99.9% of the time there is no issue telling them apart. Runways also have extra approach lights etc. at night to really make it clear where you should be pointing the nose.

(NB: Check out the video posted elsewhere in this thread of the cockpit view of a 747 landing at SFO at night. It is pretty clear which is the runway and which is the taxiway).

However, it is those 0.01% of the times where the weather is bad, or you are landing into the sun or the traffic is really congested and you are trying to talk on the radio at the same time etc. where mistakes can be made.

In this particular scenario in the OP, I am assuming that having 4 heavy aircraft lined up on the runway pointing at the landing plane, then 4 sets of bright landing and navigation lights on the taxiway could have looked like runway lighting, and disoriented the Canada Air pilot? Just outside speculation here, but stranger things have happened.

It's like the case of the Air New Zealand CD-10 crash into Mt. Erebus in clear weather. Non pilots were incredulous that a plane could fly into the side of a mountain in clear daylight weather, but the visual trickery played by bright snow on a slope actually fooled ALL pilots on board that they were flying down a valley instead of into an upward slope. [0] (A badly programmed navigation computer didn't help at all.)

[0] - https://en.wikipedia.org/wiki/Air_New_Zealand_Flight_901

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