Runway Field Clearance Floor - Honeywell MK VI Pilot's Manual

Terrain
Clearance
Floor
Continued
Runway
Field
Clearance
Floor
28
Runway selection logic incorporates comprehensive aircraft posi-
tion and navigation information to evaluate proximity runways
and determine the most likely destination runway for all alerting
purposes.
A Runway Field Clearance Floor feature is similar to the TCF
feature except that RFCF is based on the current aircraft posi-
tion and height above the destination runway, using Geometric
Altitude (in lieu of Radio Altitude). This provides improved pro-
tection at locations where the runway is significantly higher than
the surrounding terrain as illustrated below. With version -022
and later models, the inner limit of the RFCF envelope is moved
from 1 nm to 1/2 nm of runway end, if runway and position data
is of high integrity.
TCF and RFCF alerts result in illumination of the EGPWS alert
lights and the aural message "TOO LOW TERRAIN". The audio
message is provided once when initial envelope penetration oc-
curs and again only for additional 20% decreases in Radio or
Geometric Altitude. The EGPWS alert lights remain on until the
TCF/RFCF envelope is exited.
RFCF Alert Envelope
060-4314-000 • Rev. C - May 2004
MK VI & MK VIII EGPWS Pilot Guide