[tjohns]

You don't really need more security, because if a pilot gets an ATC instruction that doesn't make sense, they're going to question it. Pilots aren't following instructions blindly, everything is mentally cross-checked against what we expect should be happening for situational awareness. (And ATC would also hear the interloper and immediately speak up.)

On top of that, almost everyone in the US also has some form of collision avoidance technology now, as well (either TCAS or ADS-B).

And there's plenty of times where the only time I could hear ATC was with the squelch full open, trying to pick a faint signal out through the static. Digital modes are terrible for this.

[H8crilA]

Eh, I get a lot of pushback in this thread. But I'll reply.

We're talking about something like a landing clearance. It doesn't have to be completely off the chart. And yes you can inject a message like that successfully, without the ATC ever knowing.

TCAS is equally broken - doesn't have authentication codes / signatures. It's actually more vulnerable since it has higher priority than ATC.

Digital modes can encode speech more efficiently than analog modes, thus reaching further on the same link budget. For example ADS-B is "audible" as far as the curvature of the planet allows - my own antenna can hear messages from up to 200mi away.

It really is a serious problem.

[tjohns]

At least in the ham radio community, experience is that digital radio sounds better further, but at the extreme ends of signal reception the digital signal becomes completely unusable before an analog signal becomes unintelligible.

See: https://en.m.wikipedia.org/wiki/Cliff_effect

https://www.selby.com.au/blog/what-is-the-digital-cliff-2

Up in the air, I can also hear AM analog voice transmissions from 200 miles away, so that's not really a good measure of performance. Both modes already do that. Benefit of having an unobstructed line of sight from several miles of altitude. :)

[H8crilA]

I mean, to put it simply it would just work with a digital mode. But that's not the point, the main point is that there is no authentication mechanism. Such systems are indeed being abused, for example trains were recently halted in Poland. This happened because they have an un-authenticated channel of communication that allows anyone to do that:

https://cybernews.com/news/century-old-technology-hack-broug...

It's only a matter of time before this happens in aviation, but unlike in the trains case it doesn't have to be just an availability problem (all trains stopped safely), it can be a "remote code execution" problem.