|Emergency Search:||9 nearest airports, VOR's, NDB's, intersections, or user waypoints; 2 nearest FSS with frequncies; 2 nearest ARTCC frequencies||Alarms:||Arrival, Proximity, Timers|
|Receiver:||PhaseTrac12, 12 parallel channel receiver, simultaneously tracks and uses up to 12 satellites to compute amd update position||Acquisition Time:||15 seconds (warm), 45 seconds (cold)|
|Update Rate:||1/second, continuous||Accuracy:||15 meters|
|Interfaces:||ARINC 429, plotting (NMEA 0183 v2.0), aviation, PC interface, altitude serializer, fuel sensor, fuel/air data computer||Map Datums:||124 predefined, 1 user defined|
|Size:||6.25 x 2 x 5.8 inches||Weight:||41 ounces|
|Certification:||TSO C37d Class 4 (VHF Transmitter) TSO C38d Class C (VHF Receiver) AC 20-138 (VFR) (GPS Receiver)||VHF Transceivr Performance:||760-channel 118-136.975 MHz 5 watt minimum transmitter power|
|Comm Features:||Auto squelch control, standard headset output with sidetone and audio leveling, stuck mic transmission timeout, emergency channel select, "autotune" frequency selection||Navigation Features:||Search and rescue operation (ladder search), pilot-defined course selection and waypoint hold, closest point of appraoch, dep and arr. frequencies|
|Planning Features:||True airspeed, density altitude, winds aloft, RAIM availability, Sunrise/Sunset calculations, and trip, fuel and VNAV planning||Moving Map Features:||14 map scales from 0.5 to 300 units, with nearby waypoints, navaids and sectorized airspace, runway and navigation data displayed. Autozoom feature automatically keeps present position and destination on the map, with user-selectable track up, north up or DTK up display.|
|Part Number||GPS Description:|
|010-00122-00||Complete system w/install kit, GA-56 GPS antenna, database & manuals|
|011-00295-00||GPS/Comm unit only; P/N that is actually on dataplate|
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Garmin issued Service Advisory No. 1930 Rev B on August 13, 2020 which stated that repair services and service parts were discontinued for the GPS-155XL, GNC-250XL, and GNC-300XL units.
An altimeter does not measure altitude on the GNC-250XL. The altimeter in the aircraft measures air pressure. The altimeter is calibrated to display a certain change in altitude based on a change in air pressure. For every inch of mercury pressure change, the altimeter displays a change of approx. 1000 ft. of altitude. The GPS does not use air pressure to determine altitude and is not subject to the pressure errors in determining altitude. Therefore, the GPS derived altitude is almost always more accurate than an altimeter. Since everyone uses a pressure-based system to determine altitude, it is integral to utilize a pressure sensitive altimeter to ensure required vertical separation.
For handheld GPS receivers, database updates can be ordered and downloaded directly through Garmin's Internet site.
For panel mount GPS receivers, all database cards and computer downloads (if applicable) must be ordered through Jeppesen. Contact Jeppesen at www.jeppesen.com for more information.