Overloaded Frequency Procedures

I am wondering if there are currently any established procedures for overloaded frequencies?

Drawing from my own experience flying business aircraft in the Los Angeles area, there have been a couple of times that ATC has broadcast:

"ATTENTION ALL AIRCRAFT, DUE TO EXCESSIVE FREQUENCY CONGESTION, DO NOT READBACK INSTRUCTIONS"

While It was a bit weird not responding to calls, It was necessary to decongest the frequency so that the controller could regain efficient flow of the traffic without needing to pause between each call to receive a read back from every pilot.

Please drop a comment below letting me know if this is something that would make sense. I can see this being effective, especaially on Expert server where a certain level of capability can be expected.

Cheers!

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Hey!

There are indeed procedures for IFATC in the sim for these situations - messages like “Do not send duplicate messages,” or “Frequency is busy, be patient” to individual aircraft, or even “Frequency busy, transmit only important messages” as a broadcast are instrumental in managing workload.

For more information, check out these awesome guides to IFATC instructions for Ground and Tower, and for Radar too.

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I’m not sure if this is necessary to be honest. While the idea is good, instructions for individua pilots get sent to that pilot directly taking precedent over other frequency chatter. Also, when I’m controlling, I usually don’t even really pay attention to the voices. I just click the flashing plane and respond, sometimes 45 seconds before I even hear the request. This is just my take, but others may be different.

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Also, we must remember that unlike the real world, IF has the advantage that we can read ATC instructions and commands and have pre-selected responses, rather than rely only on audio for a readback. I have yet to meet an IFATC controller who waits for the entire “voice” portion of the message to finish before responding. We tend to read the messages much more quickly (and sometimes don’t even pay attention to the voice!).

The ATC system in IF is essentially a super-efficient CPDLC system on steroids if you think of it!

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I may be wrong but I feel like what you’re describing would only be necessary if, like in IRL, we would need the comms clear to send the next command.

I’m Infinite Flight, ATC and pilots are able to send commands while others are also simultaneously sending commands, so that’s not an issue for us.

We can completely ignore the text-to-speech as it’s not what is used to determine who is currently able to send or receive messages.

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If so, what do you think is stopping the real world from implementing an IF-like CPDLC “super” system more widely as a way to deal with the overloaded frequencies? Is it possible?

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thanks! im aware of these procedures, I just feel that there are times where personally, it is helpful to be able to just give radio calls without having to receive a read back of the instruction!

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that is certainly true, appreciate the thoughts!

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CPDLC is actually mandatory for aircraft in the North Atlantic Mandate Area between FL290-410 and in the Eurocontrol UIR above FL285. It’s also used by multiple US airports to give pre-departure clearances (PDCs) right at the gate, so there’s no lengthy readback for IFR clearances.

There are a number of reasons that it’s not widespread yet. One reason is that a lot of aircraft — especially the smaller ones — don’t have CPDLC capability. It’s pretty expensive to install and not practical for smaller aircraft. You need a dual-channel VHF system dedicated only to datalink, a CPDLC-capable FMS, and a display to see and verify the messages. Plus the installation and the STC (supplemental type certificate) costs. And of course, given that most smaller aircraft don’t fly at the upper levels where it’s more mandatory, it makes no sense for them to get into all of these costs.

Also in other areas of the world, the technology isn’t yet equipped to handle efficient CPDLC (for example in India, CPDLC is only available on HF frequencies, transmitted via the ACARS system).

More critically, CPDLC is currently used for “non-urgent” strategic messages. The uplink and downlink time, and the receiver/response time for CPDLC is longer, when compared to voice/radio telephony, which is pretty much instant.

So in answer to your question, is it possible? Yes, but not anytime soon. The technology is still some decades away

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Wow, that’s a great answer! Very informative. It would have taken ages for me to piece that together from separate sources to even attempt such an overview. Thank you!

And a great original question that brought it up in the first place!

I might not have guessed an uplink/downlink lag would be an issue. But the cost and complexity you highlighted was particularly interesting. It’s just fascinating that with all the technology available today that the legacy ATC communications of human voice sharing a single channel is still the go to method. One can certainly imagine building a real world system that works just like the IF ATC system at its core: the the ability to receive simultaneous messages from multiple aircraft that then get stacked in a que for managing. Obviously this implies multiple rather than a single physical channel of communication. This is done all the time of course with the internet (as in IF). But I would suspect there’s also a resiliency issue, and a human factor issue. The legacy, independent transmitters, on a swarm of aircraft are immune from a system failure. As far as the human aspect, directness of human voice to voice is more nimble in dealing with the unexpected? And perhaps there is very real though intangible information in the business-as-usual vs irritation in a controller’s voice that is more difficult to transcribe in text or through voice synthesis?

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From my rather inexperienced point of view, it’s possible that giving the PM a chat-like comms history to search through on top of existing monitoring duties would needed to be carefully considered… Could be very distracting especially once established and expecting callouts etc.

My two cents from just a few days on the training server and lots of random learning before that.

Most common reason is when the planes connect to your frequency in wrong time or atc ask the planes to connect to early.

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