Mark V and Mark VII EGPWS Pilot's Guide
Rev H, August 2011
The filtered difference between Corrected Altitude and GPS
Altitude exceeds a computed threshold based on the current
estimated altimetry system errors.
The there are two selectable options for the Above Transition
Altitude - Altimeter monitor. The first option compares
Corrected Barometric Altitude with Uncorrected Altitude and
generates an annunciation if the difference is greater than the
specified threshold after the aircraft has climbed above the
transition altitude. This option is applicable to Boeing
installations and other aircraft, except Airbus, where the
corrected altitude output from the ADC (typically label 204)
equals uncorrected altitude when the barometric reference is
set to standard.
The second option is applicable to Airbus installations where
the Corrected Altitude output from the ADC is not set to
standard setting when the barometric reference is set to
Standard. In these installations, the barometric reference
setting is directly received by the EGPWS. An advisory will
be generated if the barometric reference is not set to standard
after passing through the transition altitude.
The Above Transition Altitude - Altimeter Monitor advisory
is generated when the following conditions are met:
• Corrected Barometric Altitude, Uncorrected Barometric
Altitude, and Runway Database are valid.
• The aircraft has been above the transition altitude for
more than 30 seconds and not more than 5 minutes.
The difference between Corrected Altitude and Uncorrected
Altitude is less than the fixed threshold or the Barometric
Altitude Reference does not equal standard, depending on the
selected monitor option.
The aural message consists of the phrase "Altimeter Setting".
This aural message is issued once when the altimeter error is first
detected and will repeat once, 8 seconds later. After two
messages, no additional message will be generated.
The monitor will be re-armed if the enable logic goes false and
then true or after a change in the altimeter setting is detected by
By default, the aural message is generated at the EGPWS
Warning volume, but the audio level may be adjusted to a
different level using the RCD.
In addition to the aural annunciations provided, visual text
annunciations can also be overlaid on the terrain display for a
period of time when the monitor condition is entered.