3 The TERRAIN AHEAD – PULL UP warning (or the equivalent FAA warning) always precedes the AVOID TERRAIN warning.
4.1.5.3. EGPWS: OBSTACLE
The Obstacle option uses the same TAD algorithm for terrain detection. Only the visual and aural alerts differ.
OBSTACLE AHEAD Caution OBSTACLE AHEAD4 every seconds until conditions disappear. OBSTACLE AHEAD Warning 7 OBSTACLE AHEAD – PULL UP5 repeated until condition disappears.
The displays on ND are similar to the ones for TERRAIN caution and warning. The term OBST replaces the term TERRAIN. The wording varies in the same way according to the regulations (EASA or FAA). Refer to 4.1.5.2 – TAWS Predictive Functions.
4.1.5.4. EGPWS: PEAKS MODE
The Peaks mode display is optional. It improves the terrain awareness of the flight crew by displaying the terrain data further than 2 000 ft below the aircraft. Refer to Figure 4-4.
The highest and the lowest terrain altitudes are displayed in the ND bottom right corner. The lowest terrain altitude is available on EIS2 only. Refer to Figure 4-17.
4 The European EASA regulations require the wording OBSTACLE AHEAD. The FAA regulations
require CAUTION OBSTACLE.
5 The European EASA regulations require the wording OBSTACLE AHEAD – PULL UP. The FAA
regulations require OBSTACLE OBSTACLE – PULL UP.
4.1.5.5. TERRAIN DISPLAY IN POLAR AREAS
The terrain database is coded in latitudes/longitudes (spherical coordinates) and the ND is graduated in NM (plane cylindrical coordinates). The TAWS translates the latitudes/longitudes into distances (i.e. projection of a spherical image on a plan). At high latitudes, discontinuities appear in the terrain display (refer to Figure 7-10). Only EGPWS is affected.
The T2CAS assigns a unique elevation to the region that is above 75° of latitude (North or South). This unique elevation is the highest elevation of the region above 75° of latitude (North or South). Refer to Figure 4-18.
In other words, the T2CAS considers this region as a cylindrical mountain. The height of this cylindrical mountain is equal to the highest elevation in this region.
Figure 4-19 provides the areas contained in the N75° and S75° circles.
4.1.6. TAWS CONTROLS
4.1.6.1. A300/A310 CONTROLS
Figure 4-20: GPWS landing SLATS/FLAPS switch GPWS LANDING SLATS/FLAPS: TAWS activation of the 15/20 slats/flaps configuration for A300-600 (or 20/20 for A310) if the landing is not performed in 30/40 slats/flaps configuration.
Figure 4-21: Control panel on Captain side GPWS G/S MODE: Inhibition of Mode 5 – Excessive Glide Slope Deviation. TERR MODE: Inhibition of predictive functions (TAD/TCF for EGPWS or CPA/THD for T2CAS). GPWS: Inhibition of basic functions. GPWS Selector switch: OFF: Inhibition of all warnings. FLAP OVRD: Inhibition of TOO LOW FLAPS alert. NORM: All GPWS warnings available.
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