HAZARD AVOIDANCE

6.4 TAWS (OPTIONAL)

TAWS (Terrain Awareness and Warning System) is an optional feature to increase situational awareness and aid inreducingcontrolledflightintoterrain(CFIT). TAWSsatisfiesTSO-C151bClassBrequirementsforcertification. Class B TAWS is required for all Part 91 aircraft operations with six or more passenger seats and for Part 135 turbine aircraft operations with six to nine passenger seats (FAR Parts 91.223, 135.154).

TAWSprovidesvisualandauralannunciationswhenterrainandobstaclesarewithinthegivenaltitudethreshold from the aircraft.

REQUIREMENTS

TAWS requires the following to operate properly:

•The system must have a valid 3-D GPS position solution.

•The system must have a valid terrain/obstacle/airport terrain database.

LIMITATIONS

NOTE: The data contained in the TAWS databases comes from government agencies. Garmin accurately processes and cross-validates the data but cannot guarantee the accuracy and completeness of the data.

TAWS displays terrain and obstructions relative to the altitude of the aircraft. The displayed alerts and warnings are advisory in nature only. Individual obstructions may be shown if available in the database. However, all obstructions may not be available in the database and data may be inaccurate. Never use this information for navigation or to maneuver to avoid obstacles.

Terrain information is based on terrain elevation information in a database that may contain inaccuracies. Terrain information should be used as an aid to situational awareness. Never use it for navigation or to maneuver to avoid terrain.

TAWSusesterrainandobstacleinformationsuppliedbygovernmentsources. Thedataundergoesverification by Garmin to confirm accuracy of the content, per TSO-C151b. However, the displayed information should never be understood as being all-inclusive.

TAWS ALERTING

TAWS uses information provided from the GPS receiver to provide a horizontal position and altitude. GPS altitude is derived from satellite measurements. GPS altitude is converted to a mean sea level (MSL)-based altitude (GPS-MSL altitude) and is used to determine TAWS alerts. GPS-MSL altitude accuracy is affected by factors such as satellite geometry, but it is not subject to variations in pressure and temperature that normally affect pressure altitude devices. GPS-MSL altitude does not require local altimeter settings to determine MSL altitude. Therefore, GPS altitude provides a highly accurate and reliable MSL altitude source to calculate terrain and obstacle alerts.

TAWS utilizes terrain and obstacle databases that are referenced to mean sea level (MSL). Using the GPS position and GPS-MSL altitude, TAWS displays a 2-D picture of the surrounding terrain and obstacles relative to the position and altitude of the aircraft. Furthermore, the GPS position and GPS-MSL altitude are used to calculate and “predict” the aircraft’s flight path in relation to the surrounding terrain and obstacles. In this

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manner, TAWS can provide advanced alerts of predicted dangerous terrain conditions. Detailed alert modes are described later in this section.

BARO-CORRECTED ALTITUDE VERSUS GPS-MSL ALTITUDE

Baro-corrected altitude (or indicated altitude) is derived by adjusting the altimeter setting for local atmospheric conditions. The most accurate baro-corrected altitude can be achieved by frequently updating thealtimetersettingtothenearestreportingstationalongtheflightpath. However,becauseactualatmosphere conditions seldom match the standard conditions defined by the International Standard Atmosphere (ISA) model (where pressure, temperature, and lapse rates have fixed values), it is common for the baro-corrected altitude (as read from the altimeter) to differ from the GPS-MSL altitude. This variation results in the aircraft’s true altitude differing from the baro-corrected altitude.

USING TAWS

During G1000 power-up, the terrain/obstacle database versions are displayed along with a disclaimer to the pilot. At the same time, TAWS self-test begins. One of the following aural messages is generated:

•“TAWS System Test OK”

•“TAWS System Failure”

TAWS information can be displayed on the following pages:

• TAWS Page	• AUX - Trip Planning Page
• Navigation Map	• Flight Plan Pages
• PFD Inset Map

TAWS can also be displayed on the PFD Inset Map by pressing the INSET Softkey, then the TERRAIN Softkey. TAWS display may also be deselected from the Inset Map without affecting the display on the MFD maps.

TodisplayTAWSdataonanypageotherthantheTAWSPage,presstheMAPSoftkey,thenpresstheTERRAIN Softkey. Terrain and obstacles with heights greater than 200 feet above ground level (AGL) are displayed in three color levels (Table 6-8). The G1000 adjusts colors automatically as the aircraft altitude changes.

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TAWS PAGE

The TAWS Page is in the MAP group of pages and displays the following:

•GPS-derived MSL altitude in increments of 20 feet or 10 meters, depending on unit configuration

•Aircraft ground track

•Terrain Range - Indicates the terrain elevation in colors relative to the aircraft altitude

•Range marking rings (360º View: 1 nm, 1 and 2 nm, 2.5 and 5 nm, 5 and 10 nm, 12.5 and 25 nm, 25 and 50 nm, 50 and 100 nm, 100 and 200 nm) (Arc View: 1 nm, 2 nm, 5 nm, 10 nm, 25 nm, 25 and 50 nm, 25 and 100 nm, 25 and 200 nm)

•Heading Box (North Up, Track Up, DTK Up, HDG Up) - Heading on the TAWS Page displays ‘HDG Up’ map data, unless there is no valid heading

•Obstacles

•Potential Impact Points

Displaying the TAWS Page:

1)Select the NAV Page Group.

2)Select the last rectangular page icon.

3)Turn the Joystick clockwise to display a larger area or counter-clockwise to display a smaller area.

Red Terrain (Warning

- Terrain Above or

Within 100’ Below

the Aircraft Altitude)

Map Range

Yellow Terrain

(Caution - Terrain

Between 100’ and

1000’ Below the

Aircraft Altitude)

Black Terrain (No

Danger - Terrain More

than 1000’ Below the

Aircraft Altitude)

Terrain Legend

Figure 6-47 360˚ View on the TAWS Page

The TAWS Page has two view settings:

•360˚ View—Displays surrounding terrain on all sides of aircraft (Figure 6-47).

•ARC (120˚) View—Displays terrain ahead of and 60˚ to either side of the aircraft flight path (Figure 6-48).

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Changing the viewing mode between 360° and Arc:

1)Select the TAWS Page.

2)Press the VIEW Softkey.

3)Press the 360 or ARC Softkey to select the desired view.

OR:

1)Press the MENU Key. The page menu is displayed with either ‘View Arc’ or ‘View 360º’. Press the ENT Key to change the view.

2)Turn the Joystick clockwise to display a larger area or counter-clockwise to display a smaller area.

Red Terrain (Warning

- Terrain Above or

Within 100’ Below

the Aircraft Altitude)

Map Range

Yellow Terrain

(Caution - Terrain

Between 100’ and

1000’ Below the

Aircraft Altitude)

Black Terrain (No

Danger - Terrain More

than 1000’ Below the

Aircraft Altitude)

Terrain Legend

Figure 6-48 TAWS Page (ARC View)

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Other aviation information such as airports, VORs, and other NAVAIDS can be displayed or hidden on the TAWS Page (Figure 6-49).

Showing or hiding aviation information:

1)Press the MENU Key.

2)Select ‘Show (or Hide) Aviation Data’ and press the ENT Key.

Figure 6-49 TAWS Page Menu

TAWS MANUAL TEST

NOTE: TAWS SystemTesting is disabled when ground speed exceeds 30 knots in order not to impedeTAWS alerting.

TAWS provides a manual test which verifies the proper operation of the aural and visual annunciations of the system prior to a flight.

Manually testing the TAWS System:

1)Select the TAWS Page and press the MENU Key.

2)Select the ‘Test TAWS’ option.

3)Press the ENT Key to confirm the selection.

One of the following aural messages is generated:

•“TAWS System Test, OK”

•“TAWS System Failure”

TAWS TEST is annunciated in yellow on the TAWS Page and in white on the PFD.

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