Joined: 11 Dec 2005
|Posted: Sun Jul 29, 2012 7:05 am Post subject: GPWS (Technical Notes)
|When airplane is higher than 2,000 feet above terrain:
When airplane is higher than 2,000 feet above terrain, density based on obstacle height, peaks height, and airplane altitude:
• solid green – highest obstacles or peaks displayed
• high density green – intermediate height obstacles or terrain peaks displayed
• low density green – lowest obstacles or terrain peaks displayed
When airplane is lower than 2,000 feet above terrain:
The dotted colors become the terrain pattern on the ND.
When airplane is lower than 2,000 feet above terrain, color and density based on obstacle height, terrain height, and airplane altitude:
• dotted green – obstacles or terrain from 2,000 feet below to 500 feet (250 feet with gear down) below airplane altitude
• dotted amber – obstacles or terrain 500 feet (250 feet with gear down) below to 2,000 feet above airplane altitude
• dotted red – obstacles or terrain more than 2,000 feet above airplane altitude
• dotted magenta – no terrain data available
• solid amber – look–ahead terrain caution alert is occurring
• solid red – look–ahead terrain warning alert is occurring
Note: In areas without obstacle or terrain data, look–ahead terrain alerting and display functions not available. GPWS immediate alerts function normally.
Note: Terrain within 200 feet of the nearest airport runway elevation is not displayed.
Displayed automatically when:
• a look–ahead obstacle or terrain alert occurs, and
• TERR not selected on either ND, and
• respective ND is in MAP, MAP CTR, VOR, or APP mode
Look-ahead obstacles and peaks terrain alerts are provided by monitoring obstacle and terrain proximity using a world-wide terrain data base and an obstacle data base. The obstacle data base is not yet world wide. Terrain data is not designed to be an independent navigation aid.
Obstacles or terrain ahead of the airplane may exceed available climb performance. A GPWS caution or warning does not guarantee obstacle or terrain clearance.
Terrain/Obstacle "Pull Up" annunciation comes at 20 to 30 seconds from projected impact with terrain/obstacle.
Terrain/Obstacle "Caution" annunciation comes at 40 to 60 seconds from projected impact with terrain/obstacle.
GND PROX G/S INHIB Switch – inhibits GLIDE SLOPE alert when pushed below 1,000 feet radio altitude.