Garmin 400 Series Pilot's Manual Addendum

Also see for nuvi 500-Series: User manual Pilot's guide Owner's manual Quick reference guide Owner's manual

Contents

Garmin 400 Series Pilot's Manual Addendum Manual pdf 64 page image

56Section 3TAWS AlertsPremature Descent Alerting (PDA)Garmin TAWS issues a Premature Descent alert when the system detects that the aircraft is significantlybelow the normal approach path to a runway. There are three different scenarios to consider with PDA:• No Approach Loaded—PDA alerting begins when the aircraft is within 15 nm of the destinationairport and ends when the aircraft is either 0.5 nm from the runway threshold OR is at an altitude of125’ AGL while within 1 nm of the threshold. During the final descent, algorithms will set a threshold foralerting based on altitude, distance, and other parameters.• Non-Precision Approach Loaded—PDA alerting begins when the aircraft is within 15 nm of thedestination airport and the aircraft is on the flight plan path. Again, algorithms are used to set a thresholdfor alerting based upon various parameters (Figure 3-2). PDA alerting ends at 0.5 nm from the runwaythreshold OR at an altitude of 125’ AGL while within 1 nm of the threshold.• ILS Approach Loaded—PDA alerting begins when the aircraft is within 15 nm of the destination air-port and the aircraft is on the flight plan path. Prior to crossing the FAF, the pilot will receive a PDA alertif the aircraft descends more than 200’ below the FAF crossing altitude. Once the aircraft crosses the FAFand is inbound to the runway, PDA will alert the pilot if the aircraft descends 0.7° below the ILS glideslope(Figure 3-3). PDA alerting ends 0.5 nm from the runway threshold OR at an altitude of 125’ AGL whilewithin 1 nm of the threshold.0.5 nmRunway ThresholdFinal Approach Fix200' below FAF Altitude15 nmCAUTIONFigure 3-2: Example of Non-Precision Approach PDA alertthreshold. The threshold for the descent is computed by algo-rithms based on varying flight conditions.CAUTION — The above annunciation and pop-up ter-rain alert are displayed during a PDA alert. For TAWS,the PDA alert is acompanied by the aural message “TooLow, Terrain”.PDA Severity LevelsRunway ThresholdFinal Approach Fix200' below FAF Altitude15 nmCAUTIONPDA Alert is0.7 Below GlideslopeGlideslope Intercept0.5 nmFigure 3-3: An example of a PDA alert threshold for an ILS approach