Should I use QNE, QNH or QFE for flying? Should I use QNE, QNH or QFE for flying?The Flyer has three altimeters on it, so if you really want to you could set one each to QNE, QNH and QFE.
When soaring the most useful height reading is your QFE, which shows your actual height above the ground. For most pilots, when they are comparing notes in the pub that evening and they talk about being 1000' up, they are talking about their height above the ground – their QFE.
Also, if you are in the business of avoiding controlled zones above airfields, remember that the vertical component of these is defined in feet QFE.
If by some wonderful combination of lucky weather and skillful flying you find yourself more than 3000' above the ground and in danger of encroaching on any sort of controlled airspace, then your height QNE (a.k.a. FL) is usually the one to watch. Once you are 3000' or more above the ground, heights for controlled airspace are usually (but not always) determined QNE.
If you are into the sort of flying that takes you anywhere near controlled airspace, then take expert advice – do not go by these notes.
Setting the Flyer to read QNE, QNH or QFEYou can adjust the altimeters in four ways:
Resetting all 3 altimeters to show your height QNE (also known as FL – Flight Level height). While in the ALTI section of the Menu, press and hold down the Volume button. After a short delay you will hear three blips. The reference pressure of all 3 altimeters is now set to 1013, and all height offsets cleared, so all altimeters are reading QNE.
To show your height QNH (true height above sea level). Set the reference pressure (PRS1, 2 or 3 in the Menu) to the current local 'QNH', without any height offset (to make sure there is no height offset, reset all altimeters to QNE – see above – and then do not change ALT1, 2 or 3). Remember that the QNH reference pressure can change hour by hour, although on those great steady high pressure flying days it may stay substantially unchanged for much of the day. The 'METAR' weather reports from airports around the country always include the QNH reference pressure. Metars can be found on various web sites, e.g. www.weather.uk.com/default.asp?displayme=metar&station=EGNM (the 'Pressure' given is not the actual pressure at the station, it is the QNH reference pressure to use to get true height readings at this location – for any station that is above sea level, the actual pressure there will be lower than the QNH value given).
To show your height QFE. Set the reference pressure to the current QNH reference pressure (optional – makes a small difference to accuracy), and then set the height to zero for the top of the hill or whatever other reference point you are using. You can use the ALT1, 2 or 3 setting in the Menu to zero the display for altimeters A1, A2 or A3, or in the case of altimeters A2 and A3 only you can zero the display more quickly by holding down the Enter button while the relevant altimeter is showing in normal display mode.
For preference I would like the Flyer logger to log my height QFE, since this is what matters to me – after the flight I would like to see what my maximum height was above takeoff. How irritating then that Digifly have made it so that the logged altimeter, A1, is the only one that cannot be easily zeroed.
It would be great if Digifly were to provide a user-configurable setting to determine which altimeter is used by the logger. One for the next software release, perhaps.
So far as I know the only airport in the UK where your QFE is the same as your QNH is Barra in the Outer Hebrides. Barra airport uses the beach as its runway – see www.undiscoveredscotland.co.uk/barra/airport/.
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