FAA Approved Airplane Flight Manual Supplement

Hawker Beechcraft King Air 300/300LW 190-00716-03 Rev.4
Page 158 of 167
In Figure 19 below, the approach plate notes for the same approach indicate it was designed to allow the
approach to be safely flown within a temperature range of 2°F to 114°F. Outside of this temperature
range, LNAV/VNAV minimums could not be used with uncompensated baro-VNAV systems.
Figure 19 – Approach Plate Notes
The Garmin G1000 Approach Baro VNAV system is automatically temperature compensated to produce a
glidepath position in space such that Baro VNAV approaches are always flown at the published glide path
angle when the actual temperature deviates from the ISA model. This produces results similar to ILS
glideslopes and LPV glidepaths that remain in the same position in space without respect to temperature.
To produce the correct geometric glide path angle on the final approach segment, temperature
compensation is applied to the barometric altitude and used to determine the displayed vertical deviation.
However, the altimeter continues to display uncompensated barometric altitude. The temperature
compensation required depends on the temperature profile over the altitude range between the point at
which the barometric setting is measured (presumed to be the approach airport) and the present altitude
of the aircraft. This temperature profile is estimated by using the air data system static air temperature
(SAT) and applying the standard temperature lapse rate to determine the temperature over the rest of the
range. When using barometric altitude for vertical guidance along the final approach segment,
temperature compensation is applied whether the temperature is above or below standard temperature.
The actual compensated altitude is not displayed to the pilot during an approach.
Compensating Waypoint Altitudes
In some locales, temperature compensation is required for waypoints in the approach prior to the final
approach segment due to terrain and/or obstacle clearance requirements. Currently, US operations do
not require use of temperature compensated waypoint altitudes since non-standard temperature is
factored into the approach design. Pilots operating in US airspace must request and obtain ATC
approval prior to using temperature compensated waypoint altitudes since it may result in reduced vertical
separation between aircraft. However, other countries (e.g. Canada) may require use of temperature
compensation on certain procedures.
For the G1000 system, temperature compensation of waypoint altitudes on the active flight plan page is
pilot-enabled by a menu option on the FPL – ACTIVE FLIGHT PLAN MFD page. Selecting the menu
option displays a pop-up window to allow the pilot to enter the temperature at the destination that is
cross-filled to the other GDUs so that a consistent temperature is used for temperature compensation of
published approach waypoint altitudes and the approach minimum altitude. Refer to Figure 20.
Enabling temperature compensation of published approach waypoint altitudes on one display enables it
on all displays in the system. If compensation is already active, and the temperature matches the
temperature being used for compensation of waypoint altitudes, the field at the bottom of this pop-up
page reads “CANCEL COMPENSATION?”