QFF

[K3nnyboy]

Does anyone know what QFF mean? Was reading this book and saw this under QNH and QFE. The definition seems to be a bit confusing, could anyone explain it for me please? thx !

[Mud Skipper]

2 second Google for 'Q Code' will give you;
QFF
Question; [At ... (place)] what is the present atmospheric pressure converted to mean sea level in accordance with meteorological practice?
Answer; At ... (place) the atmospheric pressure converted to mean sea level in accordance with meteorological practice is (or was determined at ... hours to be) ... millibars.
@ http://www.kloth.net/radio/qcodes.php
and this;
QFF: the mean sea level [msl] pressure derived from the barometric pressure at the station location by calculating the weight of an imaginary air column, extending from the location to sea level, assuming the temperature and relative humidity at the location are the long term monthly mean, the temperature lapse rate is ISA and the relative humidity lapse rate is zero. This is the Australian Bureau of Meteorology method; QFF calculations differ among meteorological organisations. QFF is the location value plotted on surface synoptic charts and is closer to reality than QNH, though it is only indirectly used in aviation.
QNH: the msl pressure derived from the barometric pressure at the station location by calculating the weight of an imaginary air column, extending from the location to sea level, assuming the temperature at the location is the ISA temperature for that elevation, the temperature lapse rate is ISA and the air is dry throughout the the column.
The Australian aviation regulations state that when an 'accurate' QNH is set on the pressure-setting scale at an airfield, the altimeter indication should read within 100 feet of the published airfield elevation, or 110 feet if elevation exceeds 3300 feet; otherwise the altimeter should be considered unserviceable. However due to the inherent inaccuracy possible in QNH, this may not be so. The difference between QFF and QNH when calculated on a hot day at a high airfield in Australia can be as much as 4 hPa, equivalent to about 120 feet. The advantage to aviation in using the less realistic QNH is that all aircraft altimeters in the area will be out by about the same amount, and thus maintain height interval separation.
from; http://www.auf.asn.au/groundschool/umodule3.html
So in very simple terms QFF is a more acurate form of what we know as a QNH.
Standing by to be corrected!:O

[K3nnyboy]

Thx alot man! geez...how stupid am i haha...never thought about google this kind of stuff HAHA:E so they are known as Q codes aye! kool learn something new! thx:ok:

[Andy_RR]

if not Google, then wikipedia (http://www.wikipedia.org - excuse the URL) can be a good source of info on everything and anything, including many things aeronautical.