Q - code: meteorological section
In the early part of the 20th century, communication between aviators and the ground was by means of wireless telegraphy (W/T), using the Morse Code (once radio sets had become robust enough to fit in aircraft of course). The pilot would have the transmitter key near at hand (often strapped to his/her upper leg / thigh), and would 'tap' out a message in 'morse' to ground staff, who would reply in similar fashion, the message being heard by the pilot on a headset. Later, larger aircraft (both civil and military) had radio officers on board, but the practice was still the same - W/T exchange of coded messages.
To minimise the time taken to exchange important information, and to standardise the exchange, the 'Q-code' was devised, some portions of which are still used, having been carried over into the 'R/T' (radio-telephony) era that soon replaced the cumbersome morse-code method.
The list below is not exhaustive, but gives a 'flavour' of the system as it applies to meteorology.
In these days of email, SMS/text etc., perhaps the Q-code might make a come-back!
The 'Q' part of the code indicates that a 'query' is being performed, thus the sequence " QAN LGW " heard on the ground would be interpreted as ... "what is the latest wind report for Gatwick airport?", and the reply would be along the lines ... " QAN GEO LGW 280/16KT QNT 28KT "
|QAM||(what is / here is the ) ... latest surface weather report|
|QAN||(what is / here is the ) ... surface wind (Geo after Q signal to indicate degT)|
|QAO||(what is / here is the ) ... upper wind (to be followed by height)|
|QBA||(what is / here is the ) ... visibility|
|QBB||(what is the / here is the ... ) amount and base of significant cloud above station level|
|QBC||(what is the / here is the ... ) weather report from aircraft in plain language or POMAR code|
|QBI||Instrument Flight Rules compulsory (weather unfit for visual landing)|
|QBJ||(what are the / here are the ... ) cloud tops above msl|
|QBT||(what is the / here is the ... ) runway visual range|
|QDF||(what is the / here is the ... ) difference in actual height of pressure level to height of same pressure level in ICAO standard atmosphere (the 'D' - factor).|
|QFA||(what is the / here is the ... ) route forecast (location from / to)|
|QFB||Request for fresh met.reports|
|QFC||Cloud base above msl (used for forecasts and aircraft reports)|
|QFE||Barometric pressure reduced to airfield level|
|QFF||Barometric pressure reduced to MSL|
|QFY||Present meteorological landing conditions|
|QGO||Airfield unfit for any landings (usually due to weather)|
|QMX||Temperature at upper levels|
|QNH||Altimeter setting in tenths of millibar ( I believe this used to be QUH prior to 1950)|
|QNY||Present met. conditions...plain language|
|QUB||Information in the following order: visibility, height of cloud, direction and speed of surface wind. (however, my earlier Met. for Aviators says this is QVB ... it may have changed in 1950 when the codes were updated.)|
|(and not strictly meteorological, but used to 'end' message exchange)|
|QSL||Please acknowledge / I acknowledge|