10 NM MAP NRST WPT AUX FAFIX IAFIX VOR 1 348 ° The pilot turns to intercept the course shown on the mis-set course deviation indicator. The moving map suggests  that something is wrong with the indications shown on the course deviation indicator: the aircraft is  about to depart the RNAV  approach course.  OBS 0 9 18 27 3 33 24 21 15 12 30 6 TO N A V Range KGDM KGRE KEEN KAFW SB3 C44 43M OB5 3B0 1B6 BB5 5B6 70 40 100 SFC  70 30 70 30 DEST TO TIME - - - 22:59:26 - - - - - - UTC KORH KMHT KOWD KBED KPVD KBOS Nav Source Not Communicating A C K P WR  RPM F UEL R EM O IL L EAN O AT GPH Gal F C USED h m PSI$^{I}$ N H G TAWS Trip Nrst Chkist Setup Engine Map + ABV11nm / STRK 037 030 000 Emerg. Checklist Clear Strikes Lightning Strike Traffic Above Declutter Base Map Base View Center Figure 5-9. An MFD indicating a loss of position information. Figure 5-8. Can you determine your position from a simple CDI? Figure 5-7. Discovering an incorrect navigation source selection  using the moving map. The moving map shown in  Figure 5-7  allows you to discover  a more serious programming error quickly. In this situation,  the pilot is attempting an RNAV approach. However, the  course deviation indicator (CDI) has erroneously been set  to display very high frequency (VHF) omnidirectional range  (VOR) course indications. The CDI suggests that the aircraft  is well to the west of course. The moving map display shows  the true situation—the aircraft is on the RNAV approach  course, but is about to depart it. Failure indications on the moving map can be quite subtle.  The MFD in  Figure 5-9  reflects a loss of position information,  indicated by the removal of the aircraft symbol, compass  labels, and other subtle differences. Be familiar with the  failure indications specific to your equipment. Consider the CDI shown in  Figure 5-8.  What is the position  of the aircraft with respect to the VOR station? Interpreting  this type of display requires more effort than interpreting the  moving map, which automatically displays the solution to  the position-finding problem. Pilots should expend the effort  to practice this skill set. Those who learn to navigate using  ground‑based radio navigation aids are forced to develop  spatial reasoning and visualization skills, but a Federal  Aviation Administration (FAA) study showed that this type  of skill tends to fade quickly when not used. Be sure to keep  your spatial reasoning and visualization skills sharp. The rich detail offered by the moving map display invites  you to use the display as a primary navigation instrument, but  you need to resist this temptation. The moving map display  is designed to provide supplemental navigation information,  Common Error: Using the Moving Map as a  Primary Navigation Instrument Maintaining Proficiency: Spatial Reasoning Skills Failure Indications 5-5