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Near mid-air collision at LAX between American Airlines and ITA [video]

127 points| goblin89 | 3 months ago |youtube.com

100 comments

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dehrmann|3 months ago

Is this interpretation right? There are parallel runways, and the plane departing on the runway on the right turned left, into the path of the plane departing parallel on the left?

t0mas88|3 months ago

Yes that's what happened. And this is a very common mistake.

A bit simplified, but what happens is that each flight is assigned a departure procedure during startup. That procedure is runway specific and designed to keep traffic clear of other runways so they can have traffic departing from multiple runways at the same time.

Imagine a runway on the left and one on the right, the left runway departure procedures would have an early left turn and the right runway departure procedures would be straight ahead until some altitude and then a right turn.

Now if you depart from the right runway but accidentally select the departure procedure for the left runway, the instruments (and autopilot) would indicate a left turn at about 500ft, right into the path of traffic from the left runway.

This mistake is common when for example a plane is first assigned the left runway and then during taxi changes to the right runway. Or the preflight paperwork includes the left runway departure procedure, but the actual assignment from ATC is the right runway (this was a source of incidents in Amsterdam for a while with some airlines)

If you're really interested, read this incident report via Google Translate, it describes exactly how this type of incident happens: https://www.lvnl.nl/voorvallen/20220415-verlies-van-afstand-...

SilverElfin|3 months ago

Yes exactly. They were within 1000 yards of each other and less than 5 seconds from colliding according to some videos analyzing the GPS data. If you listen to the ATC chat, the American Airlines pilot noticed the other plane going the wrong way himself and made a proactive change to avoid collision without waiting for ATC. Although the traffic controllers did notice and quickly gave out new directions, it may have been too late if the pilot didn’t act.

pedalpete|3 months ago

Is this significantly different from the near mid-air collisions that happen on a regular basis?

The audio does an excellent job of showing a layperson how difficult it is to interpret and who's going wear based on sound, and then I had to go back through the video to see the turn.

These people aren't being paid to do this right now? Is that right? I'm not American, but that's what I've heard.

7thaccount|3 months ago

Yeah. It's a super stressful job that doesn't pay well normally and now these people are having to drive Uber on the side to pay their mortgages and put food on the table. I'm definitely not flying until this is sorted out.

Deradon|3 months ago

Question for any aviation expert: Would TCAS be triggered at such a low altitude on departure?

t0mas88|3 months ago

No, TCAS alerts are inhibited at low altitude. It goes in steps by altitude (above ground) from no alerts at all, to only traffic warning but no resolutions, to resolution but no descends, to normal full operation.

goblin89|3 months ago

Yes, TCAS II warns all the way down to 100m AGL (around 320ft above the ground), and they were already between 1000ft and 1500ft (~400m).

It may or may not have advised what to do (to climb/descent/etc.) because that is turned off below 1000ft, and they were approximately at that altitude at the time.

thomascountz|3 months ago

ITY621 does a readback: "...climb DLREY," meaning they confirmed the departure path for 24L extends forward before heading left; which is different for 25R, which heads left shortly after takeoff: "...RNAV DOCKR."

IshKebab|3 months ago

Kind of blows my mind how primitive this whole system still is. Audio quality is really bad. They're sending instructions by voice. The way they know who is speaking is by just saying their callsign with every message.

There's got to be a better solution surely?

jvanderbot|3 months ago

I want you to very carefully consider the better options.

Perhaps they type instructions? And hope someone reads them?

Perhaps they drag and drop vectors? Then what, a radial menu with emergency modal screens?

Or maybe they click some buttons, forcing the occasional look away from the screen?

Maybe AI could do it all?

For this, voice is perfect. We have been following instructions by voice since humans could grunt. We do not require anyone to look away from the screen (ATC) or look down from the window outside (pilot) for any reason.

We do not require rebroadcast because everyone can hear and take initiative if required.

By what interface, specifically, should someone required to fly an airplane interact with ATC while flying that airplane? By what interface should someone who needs to see where everyone is all the time be able to contact that pilot that cannot look away from the world outside ever and cannot use their hands for anything but flying at a critical time?

Chesterton's ATC.

montecarl|3 months ago

I think that the audio we are listening too is from some ground recording station that isn't necessarily near the airport. We aren't listening to a recording of what the pilots heard or what air traffic control hears.

12_throw_away|3 months ago

Right? Just in a car, we know that talking to someone in the car itself has adverse effects on situational awareness, and talking to someone on a phone is much worse than that. But even after all the research and training that goes into human factors in aviation ... we can't do better than confusing, poor quality, AM band party lines during critical phases of flight?

evil-olive|3 months ago

> Audio quality is really bad.

as the video says at the beginning, the audio is sourced from LiveATC, which is a network of volunteers with their own radio equipment [0] who tune in to ATC frequencies and then livestream them.

those volunteers are by necessity not at the airport itself, but some distance away. and the audio is compressed to 16kbps MP3 for livestreaming purposes.

this means the sound quality we're hearing is going to be worse (significantly worse, in some cases) than what the pilots and controllers actually hear.

> They're sending instructions by voice.

I get that it's 2025 and it's tempting to say "everything should be a text message". but remember that there's 2 pilots in the aircraft, the Pilot Flying and the Pilot Monitoring [1].

under normal circumstances, the PM handles talking to ATC (among other duties). but both pilots have headsets that allow them to hear transmissions from ATC. and crucially for the Pilot Flying, they hear those messages without taking their eyes away from actually flying.

modern aircraft do have a text message system of sorts [2] but there is a very good reason why the crucial ATC instruction in this case ("turn right heading 270 immediately") happens via voice and not an ACARS message.

also, it's important to remember that airline pilots in the US have a minimum of 1500 hours of flying time, and pilots flying an A330 on an LAX-Rome route probably have significantly more than that. we're watching a 5-minute video and going "oh it's a bit hard for me to follow this" but for actual commercial pilots this radio chatter is routine and something they have been practicing for years.

0: https://www.liveatc.net/faq/

1: https://skybrary.aero/articles/pilot-flying-pf-and-pilot-mon...

2: https://en.wikipedia.org/wiki/ACARS

proteal|3 months ago

It has to do with how ATC needs to be able to communicate with all planes in the air, even ones built 100 years ago. They have to use radio so everyone can hear everyone else. There’s no other technology that is as ubiquitous as radio, so they have to work with what they’ve got. Upgrading to other stuff would be an absolute nightmare, though they are making progress on less critical fronts.

upofadown|3 months ago

Like with all voice communications, context is important. There are only a limited number of things normally said and most transmissions are about things that were decided before the flight. Everyone involved is used to the bandwidth limited audio used here. Non-pilots have none of this context and normally have a hard time understanding these transmissions.

For ATC environments the voice data is a series of pre-expected prompts. You could do something different but you would pretty much have to redesign the whole system from scratch without making things significantly more complex. Complexity is the enemy of reliability.

fujigawa|3 months ago

What do you propose that is better? VC-backed smartphone apps?

Aircraft have much better quality electronics than a $20 tabletop radio located some distance away by whoever is ripping the stream.

Loughla|3 months ago

Other than voice how would you send instructions that don't really on changing your focus? I can listen while doing other things. What else would you do?

SecretDreams|3 months ago

What's the most reliable situation you can think of that will never fail and drive better audio quality?

This is a field where they need more .9999s than Amazon.

add-sub-mul-div|3 months ago

Primitive but has been working well enough for decades is so much better than the prospect of Accenture coming in with their absolutely incompetent bullshit.

aprentic|3 months ago

I was watching KBOS https://www.flightaware.com/live/airport/KBOS on Thursday morning and saw a couple of Cape Air flights that looked like they were within 500 feet of each other. I suspect we'll be hearing more of these stories soon.

comeonbro|3 months ago

If you are casually listening to ATC for fun then you should be able to recognize that the event in this story is not ATC error...

trollied|3 months ago

Government shutdown. ATC are not being paid.

Sort your country out!

Dumblydorr|3 months ago

Most Americans have zero agency in the matter. We vote once a year or two, most of our states or districts aren’t competitive, and the candidates we do elect can ignore their constituents easily.

theodric|3 months ago

Who are you yelling at? Do you think the Trump administration reads Hacker News? What do you expect the average American taxpayer to do to fix a government shutdown?