IFR NAV - Altimetry

Define indicated altitude:

• The altitude your altimeter is indicating

• The aircraft's height above mean sea level

• The aircraft's height about the current QNH setting

• The aircraft's height above mean sea level corrected for density error

Define calibrated altitude:

• Indicated altitude corrected for density error

• Indicated altitude corrected for position and instrument error

• The aircraft's actual height above the ground

• The aircraft's actual height above mean sea level

Define true altitude:

• Indicated altitude corrected for temperature error

• The aircraft's height above the ground it is currently above

• The aircraft's actual height above mean sea level as if measured with a tape measure

• Indicated and true altitude are the same as the altimeter is self correcting

Define pressure altitude:

• Height above the prevailing mean sea level pressure

• An atmospheric pressure, expressed in terms of altitude, which corresponds to that pressure in the standard atmosphere

• Actual height above the 1013.2 hPa level

What is the difference between pressure and density altitude?

• They are just British and American versions of the same thing

• Density altitude takes into account temperature deviations

• Density altitude is only applicable one you are airborne, pressure altitude is used for performance charts

• Density altitude assume no temperature lapse rate in it's calculations

Define Flight Level (FL)

• Pressure altitude expressed in 100's of feet

• Density altitude expressed in 100's of feet

• Pressure altitude expressed in 1000's of feet

• Density altitude expressed in 1000's of feet

When climbing out of an aerodrome you are instructed to climb to FL250, when would change your altimeter to a QNE setting?

• Passing 15,000ft

• Above MSA but not above FL150

• Passing 13,000ft

• Passing FL150

You and descending from FL360 into Oamaru, when would you change your altimeter to the local QNH setting?

• When entering controlled airspace

• Passing FL150

• Passing FL130

• When instructed by ATC

QNH is:

• Atmospheric pressure at aerodrome level or at runway threshold

• The pressure calculated to exist at an aerodrome in accordance with the ICAO Standard Atmosphere and is the altimeter sub scale setting to obtain the elevation when on the ground

• The ambient air pressure currently existing at an aerodrome and is the altimeter sub scale setting to obtain the elevation when on the ground

• The aerodrome level pressure reduced to mean sea level in accordance with the ICAO Standard Atmosphere and is the altimeter sub scale setting to obtain the elevation when on the ground

QFE is:

• Atmospheric pressure at aerodrome level or at runway threshold

• The altimeter sub scale setting that will read aerodrome elevation while on the ground

• The altimeter sub scale setting what will make your altimeter read 0ft at any moment in a flight

• Not used in New Zealand