On amateur (ham) radio, we often use Q-codes, which are three-letter codes starting with the letter Q with various meanings. They were originally used to speed up Morse code communications; it might be necessary to send "Can you hear me between your signals and if so can I break in on your transmission?" fairly frequently, but you would not want to send that entire sentence regularly. "QSK?" is much shorter. Many of the codes still in common use aren't used exactly "correctly"; they've become more jargon than codes. "QRP," for example, actually means "Shall I decrease transmitter power?" and "Decrease transmitter power," but it's more commonly used as an adjective meaning low-power; you might have a QRP transmitter, meaning that the transmitter has a low maximum power setting. "QSO" means "Can you communicate with...?" or "I can communicate with...," but now often means a radio contact (as a noun); a "QRP QSO" is a contact in which one or both operators was transmitting at low power. (I don't use CW and I rarely use conversational digital modes; these codes might be used "correctly" more often on those modes.) Pronunciations are not always "correct" either; I hear people say "queue so" instead of "queue ess oh" fairly often.

There are (were?) a lot of these codes specifically intended for aviation. Are any of them still used, either the "right" way or as jargon?


2 Answers 2


The three main ones still in use relate to altimeter settings.

  • QFE refers to the current atmospheric pressure at a specified point (generally the field elevation reference point, or a runway threshold). As such, if a pilot sets their altimeter to QFE, their altimeter will read their height above that point.
  • QNH refers to the current atmospheric pressure at mean sea level. If a pilot sets their altimeter to QNH, their altimeter will read their AMSL altitude.
  • QNE refers to the value an altimeter will show when it is at the specified runway threshold, if the altimeter is set to the "standard" 29.92 inHg or 1013.25 hPa. As slang, it refers to that standard altimeter setting. This is not perfectly correct usage.

The Wikipedia entry for Aeronautical Code signals additionally lists QFF, QDM, QDL, QDR, QFU, QGE, QGH, QTE, QTF, and QUJ as being in use today. I am not sure how accurate that is; the article was created in March 2015 and is substantially unchanged since then.

  • $\begingroup$ In my 30+ years in US ATC, I never saw/heard any of them used ever. It must be an overseas thing. $\endgroup$
    – RetiredATC
    Commented Aug 17, 2023 at 15:25

Another I hear fairly regularly in UK aviation is QSY which falls somewhere between actual usage and "slang". It's a quick way of signalling to a controller that you want to change frequency (especially if they are busy) or for them to tell you to change frequency whenever you like.

I commonly hear this when crossing Luton, which is a fairly busy regional London airport.

Either from them

G-ABCD, leaving controlled airspace in 1 mile QSY (my destination airfield close by) en-route

or from me

G-ABCD, at (exit point of controlled airspace) happy to QSY (my destination close by)

When the controller is less busy, we tend to use more standard communication.


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