What happens when an air traffic controller tells an aircraft with the call sign of ‘Six-Seven-Tango’ that they are cleared to land, and the pilot of an aircraft with the call sign of ‘Six-Sierra-Tango’ says, ‘Roger. Cleared to land.’
THE PROBLEM: Cessna 5409V and Piper 9309V would have the same abbreviated call sign, so when these two airplanes share the same airspace the entire call sign will be needed. Sometimes when similar sounding call signs are on the same frequency the controller will make a special warning about the situation to the pilots involved – but do not depend on this – listen for yourself. If you should become confused you must verify that the instructions that you heard were in fact for you aircraft by saying, ‘Verify clearance for (complete call sign).’ Do not follow instructions unless you are sure they were meant for you.
THE RULES: The airplane call sign is often taken for granted, but there are specific rules that apply to the use of call signs so that confusion is reduced or eliminated.
- Your Rule — Never abbreviate a call sign unless the controller does so first. You can eliminate the ‘country code’ (United States registered aircraft numbers start with the letter N) but everything else — including the aircraft manufacturer — stays in.
Example 1: You say, ‘This is Cessna 6543Alpha.‘ The controller, who has been listening to the frequency longer that you have, will compare your call sign with all others on that same frequency. If there are no similarities, the controller might respond by addressing you with, ‘Roger 43 Alpha…‘ This is your signal that an abbreviated call sign is approved. What you do: You may use 43 Alpha to refer to yourself when talking to this controller.
Example 2: The controller determines that two or more aircraft are on the frequency that have similar call signs, and chooses not to abbreviate. What you do: Follow their lead.
- Air carriers and some air taxi operators have FAA authorized call signs that reflect the company and the flight number.
Example: You hear ‘United 312‘ used on the radio instead of ‘Boeing 769Uniform-Alpha.‘
- Military aircraft use coded call signs as well — instead of the aircraft type and number.
Example: ‘Defender 27‘ or ‘Music City 219‘ or ‘Navy 6 Golf Charlie‘ or ‘Air Force One‘ … or just about anything else they can come up with.
- Heavy Metal — Both civilian and military aircraft will add the word ‘heavy’ to their call sign when the aircraft is capable of a takeoff weight that is greater than 255,000 pounds.
Example: ‘This is USAir 451 Heavy.‘
- Experimental drivers include the word ‘experimental’ in their call sign on *initial* call up, but then omit the word after communication is established.
The controllers use of an aircraft call sign is also a code within a code, more on that next week…
Editor’s Note: The U.S. air traffic control system is currently experiencing a frequency crunch — we’re running out of efficient communication channels within the current frequency assignment system. These days, one of the most challenging aspects of flying can be just trying to get a word in edge-wise at the busier approach control facilities. But you don’t have to fly IFR to experience the problem, just listen-in over your area’s most popular Unicom/CTAF frequency at lunchtime on a good VFR weekend… Knowing what to say and how to say it is more important than ever and, until the FAA grinds out a long-term solution, education and conformity to the rules is our best defense — because the cure isn’t coming anytime soon and we’re all in this together.