[charlietran]

There's an mp3 of the radio chatter here:

https://forums.liveatc.net/atcaviation-audio-clips/7-july-ks...

> Audio from the air traffic controller communication archived by a user on LiveATC.net and reviewed by this newspaper organization showed how a the confused Air Canada pilot asks if he’s clear to land on 28R because he sees lights on the runway.

> “There’s no one on 28R but you,” the air controller responds.

> An unidentified voice, presumably another pilot, then chimes in: “Where’s this guy going. He’s on the taxiway.”

> The air controller quickly tells the Air Canada pilot to “go around.” telling the pilot “it looks like you were lined up for Charlie (Taxiway C) there.”

> A United Airlines pilot radios in: “United One, Air Canada flew directly over us.”

> “Yeah, I saw that guys,” the control tower responds.

[narrator]

The "Where's this guy going" unidentified person on the channel prevented the worst accident in aviation history. Great Job! Give that guy a medal and a movie.

[dx034]

It's likely that the controller would've seen it as well after the Air Canada pilot indicated that he saw planes on what he believed was the runway.

Even if not, the pilot would've probably aborted the landing since he saw the other aircrafts. So it was certainly a dangerous situation but I doubt that a crash would've happened without that pilot's comment (it was certainly helpful though).

[mckoss]

Controllers in the tower do not have a good visual perspective to see runway alignment. I don't think they would have caught this.

At night, there are many visual cues to see the runway environment - it sounds to me like this complacent pilot ignored many red flags and was about to drive his plane on top of those on the taxiway.

A big heavy airliner can't just stop its decent instantly; it's a good thing that pilot on the ground chimed in when he did.

I betcha the landing pilot won't have a job pretty soon.

[dsfyu404ed]

When you're descending at a rate suitable for human cargo in good weather there's plenty of room to maneuver.

A C-5 that's trying to drop out of the sky ASAP before anyone can shoot at it is a different story.

The pilot and copilot were clearly in WTF mode since there were planes on what they thought was the runway. If nobody had spoken up it would likely have gone back and fourth between them and the tower a few times ("are you sure the runway is clear?") and in all likelihood they would have caught it. If they didn't the pilots would have likely requested to go around. Backing off of what you're doing and assessing the situation when anything is not quite right is SOP in every facet of aviation.

[dx034]

But they have radar and usually extended centerlines. That should've been clearly visible for him on the screen.

[pdelbarba]

Radar displays are not going to accurately display a displacement of 150m. They're set up for broader area surveillance.

Edit: here's a good example of a terminal radar display. The two parallel diagonal lines are the extended centerlines of two runways that are about 1570m apart (Athens airport, LGAV).

https://www.hvacc.gr/site/images/content/events/2003/athens-...

[lisper]

And that's the spacing between the runways. There is less space between the runway and the taxiway.

http://flightaware.com/resources/airport/SFO/APD/AIRPORT+DIA...

[PhasmaFelis]

Yeah. When reading about modern air disasters, you often hear that five different things had to go wrong at once for them to happen. In this case, one or two things went wrong, the rest of them went right, and everything was fine.

[thrill]

This is spot on. The strength and weakness in doing something as complex as safely landing an airliner full of people is all in the capability of the human mind to use technology. Especially in flying, I think (I did this for a career, a whole other career ago) it's easy to have everything going smoothly, then some "minor" thing be out of expectation, but hey things are going smoothly, so dismiss the minor thing because here's this other thing that does look just right, and ... and ... suddenly several mistakes have compounded.

It's sometimes harder when there's nothing impeding you at all to do everything right because the routine-ness of habit takes over. Being busy (but not overwhelmed), while more mentally and physically tiring, is sometimes easier, because you pay attention to the right things at the right time.

[ghaff]

This is true in all manner of domains. I've never flown but I can remember a number of times I've made (fortunately relatively inconsequential) mistakes that caused me to face-palm afterwards. Why? Not so much that I made a mistake. But that I could recall clearly a number of observations that I made but dismissed because they ran counter to what I "knew" was the reality of my situation.

[jackweirdy]

This is like Sully all over again, but with only seconds to extract story from instead of minutes!

[stupidcar]

"Taxiway", coming to theatres near you soon. Directed by Clint Eastwood. Starring John Malkovich as The Pilot, Tom Hanks as the "Where’s this guy going?" guy, and Dave Bautista as the taxiway.

[MBCook]

Yeah but casting Pauly Shore as the controller? Bold choice.

[ubernostrum]

Listen to this recording:

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

It's from a Delta flight a few years ago that slid off the runway at LaGuardia in snow. The action starts about 5 minutes into that recording; Tower has just set up another incoming Delta flight to land, and is trying to confirm Delta 1086 has cleared the runway. Delta 1086 is poking its nose out over the water at this point, and the controller can't see it.

At around 5:56 a ground vehicle calls in to ask permission to cross the runway and gets it. Then the ground vehicle sees what's happened (Delta 1086 slid off the end of the runway), and this is where it gets interesting, because you see very quickly two important things:

1. Trusting the report: the guy up in the tower does not have a perfect view, and in fact in this incident he can't see what has happened to this Delta plane. He's getting an unsolicited report from a ground vehicle, but he believes it and acts immediately on it. If the report's mistaken, worst outcome is some planes circle a bit more before they finally land. If the report's right, though, the worst outcome is planes trying to land on a crash site.

2. Division of responsibility. From the moment the crash becomes known, it's the job of the emergency/rescue teams to figure out what's happened and deal with it. The guy in the tower probably desperately wants to know more about what's going on, but he's got planes stacked up waiting to land, and his curiosity is going to have to wait. Beyond getting confirmation of a couple unusual orders, Tower just lets the folks on the ground do their job, and sticks to doing his.

Here's a rough annotated transcript (timestamps are from the video), since I know people complain that ATC recordings are hard to make out:

6:08: Delta 1086, Tower? (trying to contact the plane that's just gone off the end of the runway -- Tower still doesn't know what's happened)

Tower, call 100, Runway 13 is closed. (ground vehicle has seen the accident)

Tower, red team to go onto 13.

Tower, you copy? Call 100, Runway 13 is closed.

Call 100, you said Runway 13 is closed? (Tower confirms what he's just heard)

Affirmative, 13 is closed.

Team red, Tower?

Tower, you have an aircraft off the runway.

6:45: Delta 1999, go around!

1999, going around.

6:50: The airport is closed. The airport is closed. We've got a 34. (ground crew saying this is bad enough the airport needs to close)

Call 100, say again?

6:59: Tower, you have an aircraft off 31 on the north vehicle service road, please advise crash rescue, LaGuardia Airport is closed at this time.

7:12: Good afternoon, Tower, Delta 2522's on the ILS for 13 (another Delta flight is lining up to land on the runway where the crash happened* -- they can't hear what's happening below)

Delta 2522, LaGuardia Tower, go around!

Go around, Delta 2522. (pilot confirms that he's going around)

From there on out, it's just Tower giving instructions to other planes on what to do, and a report from the ground to tell the pilot of the crashed plane (if he does get on the radio again) that the plane is leaking fuel from a ruptured wing.

Now: what if the ground vehicle hadn't gone out there? Or hadn't seen the crash in time, or hadn't been able to get a report to the tower in time, or the tower had hesitated a bit more in accepting the report and starting to reroute planes? A similar problem to the SFO incident, only instead of an occupied taxiway it would've been an occupied runway (and one that had already caused one plane to slide off in the snow, and now had emergency vehicles converging on it).

The point is, though, that this isn't necessarily a miracle or a lucky escape -- everybody is involved in ensuring safety, and that's what happened in both cases, providing extra layers of watchfulness which averted much more serious trouble.

* The runway is referred to as both "13" and "31" at different points; runways are numbered according to compass heading, so "13" means it's aligned to a heading of 130 degrees. The dual numbers are because you can take off or land from either end; the other number is always +/- 18, since it's 180 degrees around from the first one. In this case, the designation of the runway is 13 from one end, and 31 (for 310 degrees, 130 + 180) from the other end.

[softawre]

Super interesting, thanks for typing this all out.

[malchow]

I think the most important thing here is that we stop to think about the gender normativity of the unidentified person's use of the term "guy" in "where's this guy going."

/sarcasm

[dav]

Those fixed wings people are unflappable.

[throwanem]

You monster.

[desdiv]

.

[Aloha]

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 any wanted benefits.

As a note - the audio from this recording is very clear to me - I've heard far worse out of scratchy narrowband FM.. with AM the weaker the signal generally the quieter it is - but not generally that much noisier.

[InclinedPlane]

Yup. FM is great for noise rejection. But any signal which is not "the one true signal" counts as noise. So FM interferes with other FM signals mightily and the most powerful one tends to "win". Whereas with AM the signals just add on top of each other.

[lb1lf]

-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)

[Aloha]

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

[tialaramex]

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'm not suggesting that DSC should just be dropped in as a replacement for AM analogue transceivers on planes, but I _am_ saying that I don't buy the theory that it so happens AM analogue is the right choice and not just the result of inertia.

[pdelbarba]

I've used both marine (FM) and airband (AM) radios. My marine experience was in a relatively uncluttered environment (Cleveland) so take this with a grain of salt but I found that you rarely had people talking over each other in that environment, especially with it's limited propagation. Airband on the other hand is almost always a very high radio traffic environment if you are actively switching between tower, departure and center channels throughout the flight. It becomes imperative to be able to tell when someone stepped on ATC and you didn't get some message.

[Aloha]

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.

[sigstoat]

they still use AM because higher powered transmitters (which will generally be the tower) can overpower weaker transmitters (planes). i'm given to understand aviation is enamored of that feature.

> Just imagine the economic damage that a single asshole can do with a high-powered transmitter near an airport.

the pilots could probably just pull their cell phones out and call the tower. there is much worse trouble single assholes could get up to.

[PhasmaFelis]

I'd imagine, as well, that a transmitter powerful enough to drown out a control tower would be very, very difficult to conceal.

[RX14]

I think you'd be very surprised what a lot of power and a shit antenna can do. Obviously won't last when someone comes along with DF equipment, but it really wouldn't be hard to conceal visually.

[floatingatoll]

Visually is the key word here. RF-wise, you may as well put a beacon on the moon and scream "LOOK AT ME" for all the good it'll do when the very, very angry FAA/FCC vans show up.

[grandalf]

http://ieeexplore.ieee.org/document/369434

On the other hand, AM is simple and cheap and usable worldwide without significant investment.

[pdelbarba]

Except when said AM transceiver is inside an airplane, then it's thousands of dollars :P

[dmitrygr]

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. Sort of funny to watch it from the side

I assure you that there is a reason AM is used. The reason is that in the case that two stations are transmitting, everyone will be aware of it and the stronger signal may be heard. This is not something that FM can guarantee. And a digital protocol requires a much better signal (where old analog tv gave snowy picture digital TV gives nothing). Not to mention the insane costs that digital radio retofitting would require of every single plane in the sky.

Edit: parent seems to have deleted his post. It previously asked condescendingly why we still use AM for comms in the air.

[adrianN]

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.

[dmitrygr]

With a lot of FEC, you can sort of approach it, but still not quite. Human brain is a lot better at picking out voice out of noise than any algorithm currently known. That is , for example, why your Alexa cannot take your commands in the middle of a 100-person party, but your interlocutor can hear you and respond.

[adrianN]

That is not very relevant since humans don't use an error correcting code that is easy to understand for machines when talking to each other. So Alexa's ability to filter your voice out of the noise has little to do with the ability of two machines understanding each other over a noisy channel when they use appropriate coding.

[mikeash]

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 change would have to be very carefully considered, but I'm always happy when I get far enough from the airport that I can turn the damned thing off.

I think a digital system could be done much better than what we have. But I'm sure it's not worth the huge effort it would take to design and build.

[Aloha]

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.

[mikeash]

Thanks, now I know what to look for next time I go equipment shopping. I'm sure many GA radios have this, but I'm using particularly low-end radios since space and power consumption are more important for what I do. Still won't fix getting an earful about skydivers at an airport a hundred miles away, but it would be an improvement!

[dmitrygr]

even KY-97A from decades ago handles this for you

[wfunction]

Okay, but do military-grade systems use AM like this too? I imagine their needs aren't any less than those of civilians, and I imagine they've gotten their communication systems to work just fine. So what's the issue?

[klodolph]

"Military-grade" systems use complicated techniques like frequency-hopping spread spectrum. They're designed to be encrypted and resistant to jamming. The jamming resistance is not something we care about (if someone is jamming the signal you just make them turn off their radio), and the whole point of encryption is to prevent interoperability when you don't have the right key.

So sure, you could pay a bunch of extra money for military features and end up with a product that is even less what you want than AM radio. And then you'd have to retrofit everything with these systems.

AM is wonderful. You put a bunch of people on the same channel and it just works.

[wfunction]

> "Military-grade" systems use complicated techniques like frequency-hopping spread spectrum

Note that that technology has been around since World War II. And fun fact, while we're on that topic, this page is worth a read: https://en.wikipedia.org/wiki/Hedy_Lamarr

[tjl]

I love that a technique that's so widely used now was the co-invented by a movie star. It's also used in cell phones.

[Someone]

"The jamming resistance is not something we care about (if someone is jamming the signal you just make them turn off their radio)"

Evie might know this, too, so I think you should be concerned about jamming. Luckily, AM provides jamming resistance, since Evie would have to bring a powerful transmitter to be loud enough to drown out the other signals.

Nevertheless, I think large airports should have fast response teams who can rapidly fix the position of a jammer and silence it, if needed. If Evie could effectively take out, say, the main airports of LA and SF for a few hours with a few strong AM transmitters, I doubt all will end well.

[klodolph]

Evie? I honestly have no idea who that is. But the more powerful the jamming, the easier it is to find the source. These days even hobbyists play around with cheap off-the-shelf RF analyzers and directional antennas, so I can't imagine that someone jamming airport signals would be able to evade arrest for very long.

Heck, the FCC will even track you down if you operate an unlicensed radio station. See: https://www.youtube.com/watch?v=QIGAOLJh-XE

[saurik]

I don't understand what is so wrong with the transmission quality in that MP3. The issues I hear sound like they are simply due to trying to transmit from an extremely noisy environment (the cockpit of an airplane); they are mitigating the pilot's voice being entirely drowned in the background noise by placing the microphone right next to their mouth, but that then causes the sound of their breath to be extremely noticeable. I am not sure how to fix these issues but they don't seem to have anything to do with the usage of AM radio.

[amenghra]

In helicopters/tanks, some people wear a sensor around their neck which picks up vocal cord vibrations without pickup any breathing or external sound.

[wfunction]

I wasn't complaining about the transmission quality, I was just trying to understand the parent comment. The person who complained about the former was someone else.

[saurik]

Sorry; I misunderstood (and to be honest even after my tenth reread am still having a difficult time parsing...) the end of your comment about the "issue" :(.

[tuxxy]

Airlines don't need military systems which are used more for confidentiality and OPSEC than other things. In the field, militaries tend to avoid radio communications for various tactical reasons. Submarines are a great example of this.

[Aloha]

Generally, yes. There are some digital systems used for aircraft to aircraft communications and for a tactical datalink, but yes its AM for landing.

[wfunction]

Wow, did not know. Thank you.

[ptaipale]

Military-grade systems may not be any "less" but their needs and priorities may be different (e.g. secrecy). So different technology may be used, without any contradiction to why the current one is good for civilian air traffic.

[acchow]

> 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.

[vintageseltzer]

This kind of thinking led to Juicero.

[pdelbarba]

And applied to aviation you get the Piasecki PA97

[dx034]

Did Tesla really disrupt the car market? Sure, everyone is now building EVs but that already started before Tesla became successful. They have no market power on the overall car market.

Companies like Uber, Google, Amazon certainly disrupted markets but I wouldn't be so sure about Tesla.

[mikeash]

Nobody was building long range EVs before Tesla. Short range city cars like the LEAF are really a different category.

Volvo has credited Tesla for pushing car makers into EVs, so at least one incumbent thinks that: https://electrek.co/2017/05/17/volvo-tesla-says-stop-diesel-...

Audi seems to as well, although it's not quite as clear: http://insideevs.com/audis-electromobility-boss-i-hate-to-ad...

[coldtea]

>This kind of thinking has also lead to a ton of success in Silicon Valley. See Tesla for example.

Well, not exactly a role model for success. 2016 was the first time they made any profit in all those years -- and its uncertain if 2017 will follow.

And it might still be beaten up in all its markets (electric cars and eventually self-driving ones), not a sure winner yet.

[justinjlynn]

A broken clock is correct at least once a day.

[idlewords]

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

[caf]

A clock that flashes 12:00 is still right twice a day.

[Kliment]

So it's correct at 12 and possibly at midnight too