required underlying ground-based navigation facilities and  related aircraft equipment appropriate to the route of flight,  terminal operations, instrument approaches for the destination,  and alternate airports/heliports are operational for the ETA.  If the required ground-based facilities and equipment are  not available, the flight should be rerouted, rescheduled,  canceled, or conducted under VFR. Except for programming and retrieving information from  the GPS receiver, planning the flight is accomplished in a  similar manner to conventional NAVAIDs. Departure WP,  DP, route, STAR, desired approach, IAF, and destination  airport are entered into the GPS receiver according to the  manufacturer’s instructions. During preflight, additional  information may be entered for functions such as ETA, fuel  planning, winds aloft, etc. When the GPS receiver is turned on, it begins an internal  process of test and initialization. When the receiver is  initialized, the user develops the route by selecting a WP  or series of WPs, verifies the data, and selects the active  flight plan. This procedure varies widely among receivers  made by different manufacturers. GPS is a complex system,  offering little standardization between receiver models. It is  the pilot’s responsibility to be familiar with the operation of  the equipment in the aircraft. The GPS receiver provides navigational values such as track,  bearing, groundspeed, and distance. These are computed from  the aircraft’s present latitude and longitude to the location of  the next WP. Course guidance is provided between WPs. The  pilot has the advantage of knowing the aircraft’s actual track  over the ground. As long as track and bearing to the WP are  matched up (by selecting the correct aircraft heading), the  aircraft is going directly to the WP. There is a mixture of GPS overlay approaches (approaches  with “or GPS” in the title) and GPS stand-alone approaches  in the United States. NOTE: GPS instrument approach operations outside the United  States must be authorized by the appropriate country authority. While conducting these IAPs, ground-based NAVAIDs are  not required to be operational and associated aircraft avionics  need not be installed, operational, turned on, or monitored;  however, monitoring backup navigation systems is always  recommended when available. Pilots should have a basic understanding of GPS approach  procedures and practice GPS IAPs under visual meteorological  conditions (VMC) until thoroughly proficient with all  aspects of their equipment (receiver and installation) prior  to attempting flight in instrument meteorological conditions  (IMC).  [Figure 9-28] GPS Instrument Approaches 16DEC2010to13JAN2011 -  SE-3,16DEC2010to13JAN2011 Figure 9-28. GPS stand-alone approach. 9-29