invisible

A question from an engineer in IT field - is radio communication between the aircraft and the tower identifiable in terms to have unique channel ID (so all communication between these two entities are logged under that ID) and encrypted as well?

obscure2k

Moving thread to Travel Technology
Obscure2k
TravelBuzz Moderator

tmiw

In my experience the voice stuff in the 100ish MHz range is completely unencrypted, making it possible to receive ATC communications with simple equipment anyone can buy. (You don't want to transmit on there unless you're a pilot, however!) Pilots and ATC are required to identify on every transmission too--either airline's callsign + flight number or the tail number if general aviation. All of that is how websites like http://www.liveatc.net/ can provide their services to the wider internet.

der_saeufer

No to both. Civilian ATC kicks it old-school; it's plain old AM and can be received by anyone with a compatible radio. I had one as a kid that I think cost $15.

As pointed out above, 'logging' is accomplished by every transmission including identifying information for the aircraft, whether it's ATC or the pilot speaking. Anywhere there's ATC on the channel, it's definitely recorded. I would assume that the CTAF for airports without towers is not recorded.

gfunkdave

No, it's not encrypted. That would make it quite difficult for people to hear what's going on, and you wouldn't want a pilot who misplaced his encryption key to be flying around.

invisible

OK, I get point about encryption, but let me tell you that it can be implemented exactly the same way as https, when client devices (planes in this case) do not need to enter any key manually to ensure secured communication.

As far as logging, I do not see why each aircraft can't be issued with unique ID which is generated/matched from tail sign which then this ID is embedded into the conversational channel. But apparently the reason for NOT doing this is that it most likely require substantial expenses across the whole industry.

der_saeufer

Industry isn't really the issue, it's GA where the cost of a high-tech radio could be a significant hardship. There's still a fair number of American pilots flying around without 406MHz ELTs.

Plus, the current system works. The whole point is to make it easy for anyone to hear all transmissions relevant to a particular section of airspace, and that's accomplished best by a signal that can be received with equipment that was cheap 50 years ago.

CPRich

Considering I can just go to liveatc.net and hear communications, I'm pretty sure it's not encrypted. Everything is recorded as every transmission has the aircraft identifier, so that's how it is logged/tracked. I'm guessing it's open broadcast, no unique session ID/tracker that you can just pull up.

Jimmie76

For HF communications Selcal (with each aircraft having an identifier though this is not unique) is used to alert the relevant aircraft that the controller wants to talk to them. One reason that encryption isn't used is (as I understand it) reliability over multiple time limited conversations. So for example an ATC controller may have three conversations in the space of a minute with three different aircraft one after the other. The information is normally fairly routine but can be urgent and time critical. You don't want anything to slow down the flow of information between the two. How long is it going to take to change from broadcasting to one aircraft to another as opposed to speaking to the other aircraft? Telling one aircraft to descend and the other to ascend quickly could prevent a disaster happening.

Also having worked in broadcasting at one point in my career we always tried to keep the TX and RX chain as short as possible. In other words with the minimum of extraneous equipment in the chain as this introduces more failure points. Every conversation made between the ATC and the aircraft starts (as has been said) with identifying information so it's obvious who is talking. Introducing digital as opposed to the current AM was talked about and I don't know how far they got. One of the stumbling blocks was the need to have some sort of override in cases of emergency. Also international agreements on technology would be needed which would need to be implemented worldwide to ensure compatibility.