TM 1-1510-218-10 3B-46 DME 2 NM – Indicates that valid DME distance is not being received from  a  second  station.    The system  is  therefore  providing rho-theta   (angle   provided   by the   VOR   and   distance   from the DME) navigation data. DME 2 REC – When valid DME data is received  from  a  second  DME station, this area displays REC, the identifier and frequency of the station utilized, and the aircraft's distance from the station.   Under   these   conditions,   the system    is    providing    rho-rho navigation data. When the system is providing rho-rho navigation it  is  not  unusual  for  the  VOR  station  identifier  to  be different from either of the DME station identifiers.  It is also   possible   under   valid   rho-rho  conditions  for  the VOR data to be blanked or flagged.  It is normal during rho-rho  operation  for  the  DME  stations  to  temporarily flag due to recalculation of optimum station pair. (7)   TACAN Status Page.   The TACAN status page   may   be   monitored   to   view   the   status   of   the TACAN stations being used by the system. TACAN REC – Indicates   valid   (not   fl agged) TACAN bearing information is being  received.    The  TACAN channel and radial the aircraft is on will display. DME 1 REC – Indicates   valid   (not   flagged) DME   distance   information   is being    received.        Frequency and DME distance will display. DME 2 NM – Indicates that valid DME distance is not being received from  a  second  station.    The system  is  therefore  providing rho-theta navigation data. DME 2 REC – When valid DME data is received  from  a  second  DME station this area displays REC, the identifier and paired VHF  frequency  of  the  station utilized, and the aircraft's distance from the station.   Under   these   conditions,   the system    is    providing    rho-rho navigation   data.      When   the system    is    providing    rho-rho navigation the TACAN bearing data is dashed out. (8)   GPS  Status  Page.     The  GPS  STATUS page is used to monitor the status of the GPS sensor. (a)   State Line.   The STATE line indicates the  status  of  the  GPS  sensor.    The  GPS  sensor  may be in any one of the following states: INIT – In the process of initialization. STS – In   the   process   of   searching the sky. ACQ – In   the   process   of   acquiring satellites. TRN – Transitioning between acquisition (ACQ) and navigation (NAV) modes. NAV – In the navigation mode. NAV DAT – In the process of data collection. WARN – Degraded position information is being supplied. FAIL CPU – CPU     or     429     receiver     has failed (catastrophic). FAIL MEM – Memory has failed (catastrophic). FAIL REC – Receiver  hardware  has  failed (catastrophic). EPE – The  estimated  position  error for the GPS sensor is displayed on this line.  It is in units of feet rather than nautical     miles     due     to     the higher accuracy available from the GPS system. RESTART? – This   field   will   appear   if   the GPS   sensor   is   in   an   INIT, STA,  ACQ,  TRN,  FAIL  CPU, FAIL     MEM,     or     FAIL     REC state.  Moving the cursor over this field when it appears and pressing the   ENTER  key  will cause    the    GPS    RESTART page to be displayed. SAT SNR ELE HLT – This  area  of  the  GPS  status page  provides  information  on up  to  eight  of  the  NAVSTAR GPS   satellites   visible  to  the