QFE altitude?

[SharpeXB]

Is the QFE number you are given from ATC an elevation or barometric reading to determine the altitude to approach the ILS fix?

[Eddie]

QFE is the altimeter setting required for the altimeter to read 0 at the airfield in question.

 

QFE isn't actually used in the A-10C, rather QNH (setting for the altimeter to read your alt above MSL) is used, as it it for in most cases in most aircraft, military or otherwise. The sim ATC gives out QFE though (seems to be Russian procedure for some reason) so you'd need to convert that setting to the QNH.

[Merijn]

Converting the QFE to QNH is not possible i think. It uses the same unit, so no conversion can be done.

QNH is a standard value, 1013 hPa / 2992 inHg.

So if the give the QFE it just means that you know your altitude exactly on that location. This should be same as your radar altimeter.

 

In civilian aircraft, the pilots receive the QFE readout when they are starting up. After take off the fly to a certain 'transition altitude' (dependent of country) where they swith to the standard QNH value (1013 hPa). That's when they start to talk about flight levels instead of altitudes.

 

This way every pilot that e.g. cruises at FL180 ( 18000ft on QNH) is on the same height. If they wouldn't use QNH, 18000 ft could be different for everyone that uses a different hPa value.

[Eddie]

You have QNH confused with QNE.

 

If you're only operating from one airbase, setting the correct QNH is easy, you just adjust the altimeter until it reads the correct airfield elevation. The only time converting QFE is needed is when you're landing at a different field.

 

Here's a useful aviation calculator website fit such conversions http://www.hochwarth.com/misc/AviationCalculator.html

Edited July 28, 2012 by Eddie

[LawnDart]

QNH — The barometric pressure as reported by a particular station (local altimeter setting, reading altitude above sea level)

 

QFE — Altimeter setting referenced to airport field elevation (where field elevation equals zero feet)

 

QNE — Pressure altitude (29.92 inHg or 1013.2 mb/hPa, altitude above the standard reference plane)

 

 

Think of:

QNH = Nautical Height

QFE = Field Elevation

QNE = Nil Elevation or NEither of the other two ;)

[Flamin_Squirrel]

QFE is the altimeter setting required for the altimeter to read 0 at the airfield in question.

 

QFE isn't actually used in the A-10C, rather QNH (setting for the altimeter to read your alt above MSL) is used, as it it for in most cases in most aircraft, military or otherwise. The sim ATC gives out QFE though (seems to be Russian procedure for some reason) so you'd need to convert that setting to the QNH.

 

QFE is used by the RAF on approach, in the circuit, and when transiting a MATZ, so not just a Russian thing.

[WildBillKelsoe]

the question is, what is the intercept altitude/range for any ILS?

[Flamin_Squirrel]

the question is, what is the intercept altitude/range for any ILS?

 

Depends on the approach. 10nm is fairly typical for heavies at large civil airports, but can be much less (4nm) for smaller airports/aircraft.

 

You can work out what the intercept altitude is from your distance to the field (or vice versa). On a 3 degree glide slope, for each 1nm out from the field, you should be an additional 300ft higher. So at 2nm you should be 600ft above the field (not sea level), 5nm you should be at 1500ft etc.

[LawnDart]

the question is, what is the intercept altitude/range for any ILS?

 

That varies for each airport and approach in the real world since it depends on terrain, obstacles etc., but generally the final approach fix is ~5nm from the threshold and, as mentioned, if you multiply your distance by 300 (feet/nm) you get a close estimate of the altitude you'd need for a 3 degree glideslope (5nm x 300 = 1,500'). Just add the field elev to your number and you'll have the altitude (above MSL) to use (e.g. 1,500 + 147 = 1647 feet... Round it up to the closest hundreth, and you'll use 1,700 feet and plan on your glideslope intercept to occur just outside the 5nm fix. This is assuming you're using QNH).

 

Using that as a baseline if you don't know the published intercept altitude for a particular airport you would fly straight and level, intercept the localizer first at ~1,500 feet above the field then, once established outside the marker (5+ nm or more), intercept the glideslope from that altitude and track it down.