Ask HN: Radar and radio failures at Dallas area airports
Anyone have any clue what the cause of this disruption was/is and if it's still going on?
Umm, what? How is a fiber cut an "aging, analog system"? They even admitted that there was supposed to be redundancy in place but the system did not work.
ATC communications are still over two-way radio. It's like walkie-talkies but on aviation bands instead of citizen bands. There are digital communications in some cases but it's definitely not the baseline.
The first is the loss of the very desirable property of AM voice, which is that one station can talk over another station in an emergency and still be heard.
Another is that encryption creates lots of new problems, and solves no existing problems. The issue of people impersonating pilots on VHF AM, or broadcasting spoofed ADS-B positions is well managed procedurally and through technologies that can cross check each other. The entire system is built on the premise that no single source of information is always reliable.
Key management is a non starter, given that pretty much anyone in the world is entitled to own and operate an aircraft, and to generally fly it where they please, and so it needs to work anywhere.
The replacement needs to work on any aircraft that will operate in a civil CNS/ATM environment. That means anything from a hot air balloon to an 80 year old warbird, to an F-35 or a large transport category jet. The technology cannot be subject to any export controls globally.
Then there’s the fact there are hundreds of thousands of aircraft globally out there that would need to be retrofitted, and ground infrastructure replaced, at a cost of hundreds of billions of dollars.
Replacing a radio on an aircraft is not a case of just buying one from Best Buy and plugging it in. It needs to integrate with other aircraft systems. This means getting STCs and other approvals, with very substantial engineering effort, with varying (or nonexistent) levels of manufacturer support. The same applies for CNS/ATM systems on the ground segment.
Not really. Maybe in part 121/135 ops (not sure, I don't fly that) but that's definitely not the norm in part 91.
> Key management is a non starter
Even having just signed digital comms would be interesting.
However, frequency congestion and talking in general are the better things to target here. We have had text communication for a long time now and can send clear messages in fractions of a second. Talking on the radio is an art form to try and reduce the amount of time you are pressing xmit so as to not block others while maintaining the expected coding and being clear. Still, people get stepped on and partial messages are received and then someone has to re-verbalize what they need.
We do have things like D-ATIS and technology like ForeFlight which brings IFR filing. You can get a clearance sent to your phone while on the ground. That's about as far as things go in most part 91 ops (and many don't even approach that.) Once you are in the air, almost no personally owned aircraft have things like ACARS and all communication is done via voice over the radio. The only way to know that you are getting a wrong instruction is when others hear it and call it out. (MEOW!)
> Then there’s the fact there are hundreds of thousands of aircraft
Yeah, that's why we are where we are. We still encode NOTAMS/ATIS/TAFs in inscrutable acronyms because bytes were expensive at one point and people had to be able to interpret them with some training. The same systems re-imagined today would use less bandwidth and provide easily readable text and in many languages.
We had to slowly bring in ADS-B and then require it for certain airspace; We can do the same with other improvements. The strategies aren't even new. Yes it will cost money. Once not having it costs lives, the money won't be an issue.
From an ATC perspective there’s a bunch of possible position sources for an aircraft; MLAT, ADS-B, CPDLC/ADS-C, primary radar, SSR as well as verbal position reports from pilots, depending on a combination of location and ATC and aircraft capabilities.
The ATC system is responsible for fusing these sources to paint a track on the screen for the controller. The system (at least Eurocat and TopSky, I can’t speak for others) will throw errors if these sources don’t agree.
The controller will ask questions if the pilot says one thing and the display in front of them says another. There are established procedures for dealing with transponders transmitting garbage, for example.
If you’re tooling around in Class G in your part 91 op, then for the most part nobody’s really watching you anyway.
What may be outdated here is our trust in humans to not destroy critical parts of our infrastructure.
Outside plant is basically indefensible, so if you can't trust humans not to destroy it, you've got problems.
[1] https://www.rand.org/pubs/articles/2018/paul-baran-and-the-o...