82002-PG-F
ST3400 TAWS/RMI PILOT’S GUIDE
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ST3400 TAWS/RMI PILOT’S GUIDE
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CHAPTER 4. SYSTEM OVERVIEW
How does it work
In addition to the six GPWS alerts, the ST3400 provides predictive “look
ahead” warnings by comparing its internal terrain and obstacle database to
position information provided by the GPS or FMS navigator.
The internal terrain and obstacle database provides the basis to look ahead
of the aircraft and detect terrain or obstacle conflicts. This is accomplished
based on aircraft position, phase of flight, flight path angle, track, and
speed relative to the terrain database image forward of the aircraft.
Through sophisticated look-ahead algorithms, alerts are generated if terrain
or an obstacle conflict with the flight path angle of the aircraft. This
potential conflict area projects forward and to the side of the aircraft.
During enroute operations, a caution typically occurs approximately 60
seconds ahead of the terrain conflict. A caution will turn into a warning if
evasive action is not taken. During other operations the alert times are
shorter but cautions are always designed to occur prior to warnings. A
warning does not indicate a higher severity of threat, but simply that less
time exists for evasive action.
Topographic (TOPO) and Predictive Altitude (PRED) features provide the
pilot with fast access to new types of useful information maximizing the
pilot’s understanding of the relationship between the aircraft and the
ground in different flight situations. An image of the surrounding terrain is
represented in various colors. Terrain (inclusive of obstacles) forward,
behind and to the side of the aircraft is displayed.
Understanding Alerts, Warnings and Cautions
If any terrain alert occurs, the TAWS Alert text is shown at the bottom of
the screen and an audible alert message will occur on the cockpit audio
system. The REL (RELative Altitude) terrain display screen is
automatically selected at an appropriate range to put the alerting terrain on-
screen. This action occurs on any alert, including GPWS. If the pilot has
previously selected TAWS INH, GPWS alerts are still enabled but no
terrain will be shown.
Pilots should train to react properly to all alerts, cautions and warnings, just
as one would train to react to an aircraft stall, engine failure or any other
potential or actual emergency situation.
