Garmin GNC 420W Pilot's Manual Addendum

Also see for GDL 69: Pilot's guide addendum Pilot's guide addendum Activation Instructions Pilot's guide Activation Instructions

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Garmin GNC 420W Pilot's Manual Addendum Manual pdf 32 page image

28Part Three: Section 1TAWS Introductionatmosphere conditions seldom match the standardconditions defined by the International StandardAtmosphere model (where pressure, temperature, andlapse rates have fixed values), it is common for theBaro-Corrected Altitude (as read from the altimeter) todiffer from the GPS-MSL Altitude.Premature Descent Alerting (PDA) using GPS-MSLAltitudeThe Premature Descent Alert (PDA) is annunciatedwhen the aircraft is significantly below therecommended minimum altitude for an approach.The aircraft’s GPS-MSL altitude is compared to acalculated Above-Ground-Level (AGL) altitude alongthe estimated path to the airport. When the aircraftdescends below the calculated minimum altitude forthe estimated path, the PDA alert is annunciated.LimitationsNOTE: The data contained in the TAWS databasescomes from government agencies. Garmin accuratelyprocesses and cross-validates the data, but cannotguarantee the accuracy and completeness of the data.TAWS displays terrain and obstructions relativeto the altitude of the aircraft. The displayed alertsand warnings are advisory in nature only. Individualobstructions may be shown if available in the database.However, all obstructions may not be available in thedatabase and data may be inaccurate. Never use thisinformation for navigation or to maneuver to avoidobstacles.Terrain information is based on terrain elevationdata contained in a database that may containinaccuracies. Terrain information should be usedas an aid to situational awareness. Never use it fornavigation or to maneuver to avoid terrain.TAWS uses terrain and obstacle information sup-plied by government sources. The data undergoes veri-fication by Garmin to confirm accuracy of the content,per TSO-C151b. However, the displayed informationshould never be understood as being all-inclusive.