Where did QNH originate?

Question

Just been thinking about it, where did the name come from originally and what do the letters actually stand for?

Answer 1

It is my understanding that QNE, QFE, QNH and so on were used during WWII to confuse others, since they have no logical or discernible characteristics.

Answer 2

Like all of the "Q-Code" letters, QNH originated back in the days when air-to-ground communications were handled by a radio operator transmitting in morse code. The code was invented to make the send-receive job more efficient. i don't know how the altimeter setting was assigned "QNH", but it might have been random.

Since very few words used in aviation communication start with Q, the operator would be alerted that the 3-letter word he was receiving had a specific meaning.

It was a lot quicker for the operator to transmit QRH for example, than to send "my location is..."

Ham operators still use Q-Codes today when sending in Morse.

Answer 3

QNH is a Q code. It is a pressure setting used by pilots, air traffic control (ATC) and low frequency weather beacons to refer to the barometric altimeter setting which will cause the altimeter to read altitude above mean sea level within a certain defined region. This region may be fairly widespread, or apply only to the airfield for which the QNH was given. An airfield QNH will cause the altimeter to read field elevation on landing irrespective of the temperature. In the UK the lowest forecast value of QNH for an altimeter setting region is called the "Regional Pressure Setting" and may be used to ensure safe terrain separation when cruising at lower altitudes. In some parts of the world a similar procedure is adopted and this is known as "Regional QNH" however this name has been modified to the above in the UK for reasons of ambiguity.

QNH differs from QFE which refers to the altimeter setting that will cause the altimeter to read the height above a specific aerodrome, and therefore zero on landing. While using QFE is convenient while flying in a traffic circuit of an airfield, the most common procedure when flying "cross country" is to set the altimeter to either the local QNH or the standard pressure setting (1013.2 hPa). When 1013 hPa (mbar) is set on an altimeter subscale the aircraft's vertical position is referred to as a Flight level instead of an altitude.

A common mnemonic for QNH is "Nautical Height". Student pilots sometimes remember QNH as "Query Newlyn Harbour". Newlyn Harbour in Cornwall, UK is home to the National Tidal and Sea Level Facility which is a reference for mean sea level. Another way to remember is "Q - Not Here" meaning it refers to the pressure setting that applies away from the airfield. This is to distinguish it from QFE, which novices sometimes confuse.

Air Traffic Control will pass the QNH to pilots on clearing them to descend below the transition level, as part of air traffic control clearance, on request of the pilot or when the QNH changes

Answer 4

Thudley is right, it is a morse code that abbreviates the transmissions. otherwise you would have to receive something like

.-. /. /-.-. /. /-. /- //

.-/. /.-. /--- /-.. /.-./---/--/.//

.--. /.-. /. /... /..- /.-./.-.//

.. /... ///

that is recent aerodrome pressure is

still missing the words "recalculated to the sea level"

now simple qnh is

-.--/-./....//

and numbers follow, in the morse code of course.

some of the Q codes happened to survive even in the voice transmissions, since the three letters abbreviate entire snetence in fact.