Altitude FieldWhen the GPS 126/128 is acquiring satellites ornavigating in the 2D mode, the last known altitude isused to compute your position. In cases where the GPS126/128 has 2D coverage, entering your approximatealtitude will enable the receiver to determine a 3D fix.Note: The altitude can not be changed when theGPS 126/128 has a 3D position fix.To enter an altitude:1. Ensure that ‘ALT’ is displayed in the user-selectablefield.2. Highlight the ‘ALT’ value field, and press F.3. Enter a value, and press F.Directly below the user-selectable fields is thePosition field. The position field shows the current GPSposition in latitude and longitude (default) or a userselectable position format (see navigation setup page47). Directly below the position field is the time. Timecan be displayed as a 12– or– 24 hour clock (see systemsetup page 46).Marking A PositionThe GPS 126/128 allows you to mark and store upto 500 positions as waypoints. A waypoint can beentered by taking an instant electronic fix, by manuallyentering coordinates (pg. 21), or using the bearing anddistance to a known position (pg. 22).To mark your present position:1. Press M. The mark position page will appear,showing the captured position and a default three-digit name.2. To save a default name and symbol, press F toconfirm the ‘Save?’ prompt.To enter a different waypoint name:1. Highlight the waypoint name field, and press F.2. Make the appropriate changes, and press F.3. Highlight ‘SAVE?’, and press F.Note: To enter a different waypoint symbol or com-ment, see pg. 23.Altitude Field &Marking aPositionREFERENCE18Resetting the trip odome-ter will erase the previousmileage and set theodometer to 0.You may enter a knownaltitude to assist the GPS126/128 in establishing a3D fix.