BY ORDER OF THE SECRETARY OF THE AIR FORCE AIR FORCE ...

AFMAN 11-217V1 3 JANUARY 2005 395
correcting it to sea level pressure for a standard day. Set the reported QNH when
descending through, or operating below, the published MSL Transition Level.
With the proper QNH set, the altimeter will indicate your height above MSL. All
DOD approach criteria are based upon using QNH altimeter settings. Some also
provide QFE altitudes in parenthesis.
18.6.1.2. QNE Settings. QNE is used to indicate your height above an imaginary
plane called the “standard datum plane,” also known as “FL 0”. The established
altimeter setting at FL 0 is 29.92 inches of Mercury (IN HG), or 1013.2 millibars or
hectopascals. Set QNE (29.92) when climbing through, or operating above the
Transition Altitude.
18.6.1.3. QFE Settings. QFE is the altimeter setting issued to aircraft to indicate the
AGL height above the airport. With the proper QFE set, your altimeter should
indicate “0” on the ground. The Royal Air Force and the Royal Navy in the United
Kingdom, and in many parts of the Pacific and Eastern Europe commonly use QFE.
18.6.2. Units of Measure for Altimeter Settings.
18.6.2.1. Inches of Mercury. The unit of measure used in the US is inches of
mercury.
18.6.2.1.1. WARNING: In some areas, controllers will use shorthand to issue an
altimeter setting, which can cause confusion for crews. For example, “992” could
mean 29.92 inches or 992 mb. Insure you are using the correct units of measure
when setting your altimeter.
18.6.2.1.2. NOTE: Most USAF altimeters have the ability to display either
inches of mercury or millibars/hectopascals by use of two different barometric
scales in the window of the altimeter. Insure you are using the proper scale to set
the altimeter setting.
18.6.2.2. Millibars and Hectopascals. In most other parts of the world, the metric
system is used and you will hear the term “millibars (MB)” or “hectopascals (HPa).”
Both MB and HPa equal the same unit of pressure per square centimeter, and thus can
be used interchangeably.
18.6.2.3. Millimeters of Mercury. This is primarily used in Eastern Europe and
nations of the former USSR, and is not to be confused with millibars, which is a
different unit of measure.
18.6.2.3.1. WARNING: Do not set a millimeters value from ATC on your
altimeter using the millibars scale that is part of your altimeter because they are
NOT equivalent.
18.6.3. Transition Altitude. The altitude in the vicinity of an airport at or below which
the vertical position of an aircraft is determined from an altimeter set to QNH or QFE as
appropriate. Transition altitude is normally specified for each airfield by the country in
which the airfield exists. Transition altitude will not normally be below 3,000 feet HAA
and must be published on the appropriate charts.
18.6.4. Transition Level. The lowest flight level available for use above the transition
altitude. Transition level is usually passed to the aircraft during the approach or landing