QDM QDM QDM Request QDM

admin — Sat, 10 Jul 2010 23:59:49 +0000

Have you ever wondered what all that nonsense about QNH, QFE, QTM and so on are all about? I certainly did and I used to ask my pilot friends regularly. I was still a student then, but nobody answered me. I thought perhaps that QFE might stand for “Question for Field Elevation” and QNH might be “Question for Nautical Height” or some such nonsense. It turns out the real story is more random and less complicated. In 1912 in London the Q-Codes were created by the Radiotelegraphy Convention. For Aviation the range QAA-QNZ had been allocated, although the range QRA-QUZ are available to all stations. The ICAO then assigned meaning to many Q-Codes, presumably so that communication could be more effiicient.

However you should not use Q-Codes which are so obscure that the receiving station does not know what they mean. For example if you received:

Golf Alpha Bravo Charlie Delta Request sea level QAH and QAK

You response might be:

2 Thousand feet. Negative. Request QAU.

Luckliy as pilots we only need to remember a few Q-Codes and their meaning.

Aviation Specific

QDM – Magnetic heading to steer towards you with no wind.

QDR – What is the magnetic bearing from you

QFE – Subscale setting to indicate height above your airfield

QNH – Subscale setting to get the field elevation if I were on the ground at your airfield.

All Stations

QTE – My true bearing from you

QTM – What is your magnetic bearing.

The Q-Codes relating to bearing are sometimes used as examples for Instrument training tracking towards or from stations but these are rarely if ever heard these days.

By the way QAH is requesting a height, QAK is asking if there is a risk of collision and QAU is requesting where the fuel should be jettisoned.

Engine Flooded Cessna 172 S

admin — Tue, 24 Mar 2009 22:02:43 +0000

In the nice warm weather you can have problems starting Cessna engines, I know
I have. The last time I forgot this procedure I was reminded by the CFI what the
approved procedure was and that three hands were required to carry it out
properly.

So as it says in the official Cessna POH

“In the event of over priming or flooding”,

·    Turn off the fuel pump (no more priming is required)
·    Open the throttle (full open i.e. pushed in)
·    Continue to crank the engine (Left hand) with the mixture full lean.
This is removing the vapor from the fuel line.
·    When the engine starts, smoothly advance the mixture control to full
rich (Right hand)
·    And retard the throttle to the desired idle speed (Not sure which hand
this is).

In reality of course with only two hands you should advance (smoothly, but
quickly) the mixture so the engine doesn’t stop and the quickly, but smoothly
retard the throttle before you take off!

Another solution of course, if you have the option is to ask the instructor to
advance the mixture when the engine catches while you handle the cranking and
the throttle.

Have fun practicing that one!

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QDM QDM QDM Request QDM

Engine Flooded Cessna 172 S