Don’t Block That Frequency
I’m on the road this week but never fear! The well-known aviation blogger Plastic Pilot has kindly taken command of Fear of Landing for the day. I asked him to tell us what it is like in Air Traffic Control and he responded with the following post.
ATC Behind the Scenes
by Vincent, the Plastic Pilot
I’ve been working for ATC companies for the last nine years and gained a good understanding of how the whole system works, from both sides. Knowing what a controller working position looks like and how the guys on the other side of the radio are working makes the cooperation easier. This is what I’d like to share in this post to make you feel better when you talk to ATC…
Controllers are supported in their tasks by different systems: surveillance systems (radar, ADS-B and others) inform them about the aircraft positions, this information is linked with flight plan data.
- runway in use,
- military airspace,
- and so on.
But all this nice technology becomes totally useless if the controller loses his ability to communicate with the pilots. This is why the radio system is the most important for controller.
The radio system on the ATC side is exactly the same as in the cockpit: a controller can transmit or receive, but not both at the same time. If you talk, the controller must listen and wait till the end of your transmission. There is no override or bypass system. This is why controllers hate it when their frequency get blocked.
An Airbus 320 was lined-up, ready for take-off. The controller was waiting for the preceding landing to vacate the runway before issuing the take-off clearance. A Boeing 737 was on short final. The timing was short, but not critical. At the very moment where the controller was ready to clear the Airbus for take-off, an incoming VFR pilot started a transmission.
The pilot did not use the standard “Tower, Call-sign, good morning” initial contact message. Instead, he started a very long transmission, not using ICAO phraseology. I don’t remember the very words he used, but it was something like “Tower good morning, this is HB-XXX… a PA28 we took off from LSXX and we are requesting landing clearance. We have two persons on board. We also copied airport information Quebec and are approaching VRP N”. The message was excessively long, and sounded anything but professional. During the time the frequency was blocked, the 737 on final had to go around, because the A320 was still standing there, by lack of landing clearance.
If the VFR pilot had use a short initial contact, the controller would have answered with a “Stand-by”, and then cleared the 320 for take-off, and the 737 to land, shortly after. I’m sure you don’t want to be this kind of pilot, so please use standard phraseology and keep your messages short.
VFR pilots mostly use ground, tower and approach frequencies, where pilots can hear each other, thanks to the relative small size of the airspace served by these frequencies. It is a good radio practice to wait for a couple of seconds before initial contact on a new frequency, to make sure you won’t interrupt some other radio exchanges. When contacting an “Information” frequency, an additional problem exist: given the size of the areas served by one single controller, possibly using multiple frequencies, the risk of simultaneous transmission is increased.
Depending how sophisticated the radio system is, it is possible for a flight information service officer to work several frequencies simultaneously, but this is not always the case. When you make your initial contact, it is possible that the guy on the other side must try different transmission frequencies to answer your call. He can also be talking to someone else on a frequency you don’t monitor.
One more thing for VFR pilots… Remember that if you fly without a flight plan, controllers do not have any clue who you are and what you want to do. They have to note down everything you say on the fly, so please don’t talk too fast when you pass your message. It’s much better to transmit once, slowly and clearly, than too fast and have them requesting all information again.
Finally, if you have the opportunity to visit a local ATC facility… just do it. You will be well received and will learn a lot. Controllers like to talk to pilots, even if this is a bit more complex than before September 11th. Look for ATC open house day at your local airport and don’t miss it.
Be sure to visit PlasticPilot’s General Aviation Blog and thank him for this insider’s view of the tower. Also take a look at his exciting initiative Flying Across America with a plan to fly from Daytona Beach, FL to Catalina Island, CA and back.