the ground, the pilot has the option to cancel IFR while  in flight if VFR conditions can be maintained while in  contact with ARTCC, as long as those conditions can be  maintained until landing. Additionally, pilots can relay a  message through another aircraft or contact flight service  via telephone.  Most conventional approach procedures are built around  a primary final approach NAVAID; others, such as RNAV  (GPS) approaches, are not. If a primary NAVAID exists for  an approach, it should be included in the IAP briefing, set  into the appropriate backup or active navigation radio, and  positively identified at some point prior to being used for  course guidance. Adequate thought should be given to the  appropriate transition point for changing from FMS or other  en route navigation over to the conventional navigation to  be used on the approach. Specific company standards and  procedures normally dictate when this changeover occurs;  some carriers are authorized to use FMS course guidance  throughout the approach, provided that an indication  of the conventional navigation guidance is available  and displayed. Many carriers, or specific carrier fleets,  are required to change over from RNAV to conventional  navigation prior to the FAF of an instrument approach.  Depending on the complexity of the approach procedure,  pilots may have to brief the transition from an initial NAVAID  to the primary and missed approach NAVAIDs. Figure 4-8  shows the Cheyenne, Wyoming, ILS Runway 27 approach  procedure, which requires additional consideration during  an IAP briefing.  If the 15 DME arc of the CYS VOR is to be used as the  transition to this ILS approach procedure, caution must  be paid to the transition from en route navigation to the  initial NAVAID and then to the primary NAVAID for the ILS  approach. Planning when the transition to each of these  NAVAIDs occurs may prevent the use of the incorrect  NAVAID for course guidance during approaches where  high pilot workloads already exist.  The navigation equipment that is required to join and fly an  IAP is indicated by the title of the procedure and notes on  the chart. Straight-in IAPs are identified by the navigation  system by providing the final approach guidance and the  runway with which the approach is aligned (for example,  VOR RWY 13). Circling-only approaches are identified  by the navigation system by providing final approach  guidance and a letter (for example, VOR A). More than one  navigation system separated by a slant indicates that more  than one type of equipment must be used to execute the  final approach (for example, VOR/DME RWY 31). More than  one navigation system separated by the word“or”indicates  either type of equipment can be used to execute the final  approach (for example, VOR or GPS RWY 15).  In some cases, other types of navigation systems,  including radar, are required to execute other portions of  the approach or to navigate to the IAF (for example, an  NDB procedure turn to an ILS, or an NDB in the missed  approach, or radar required to join the procedure or identify  a fix). When ATC radar or other equipment is required for  procedure entry from the en route environment, a note is  charted in the plan view of the approach procedure chart  (for example, RADAR REQUIRED or AUTOMATIC DIRECTION  FINDER (ADF) REQUIRED). When radar or other equipment  is required on portions of the procedure outside the final  approach segment, including the missed approach, a note  is charted in the notes box of the pilot briefing portion  of the approach chart (for example, RADAR REQUIRED or  DISTANCE MEASURING EQUIPMENT (DME) REQUIRED).  Notes are not charted when VOR is required outside the  final approach segment. Pilots should ensure that the  aircraft is equipped with the required NAVAIDs to execute  the approach, including the missed approach. Refer to the  AIM paragraph 5-4-5 for additional options with regards to  equipment requirements for IAPs.  RNAV systems may be used as a Substitute Means of  Navigation when a very high frequency (VHF) Omni- directional Range (VOR), Distance Measuring Equipment  (DME), Tactical Air Navigation (TACAN), VOR/TACAN  (VORTAC), VOR/DME, non-directional radio beacon (NDB),  or compass locator facility including locator outer marker  and locator middle marker is out-of-service, i.e., the  Navigation Aid (NAVAID) information is not available; an  aircraft is not equipped with an automatic direction finder  (ADF) or DME; or the installed ADF or DME on an aircraft is  not operational. For example, if equipped with a suitable  RNAV system, a pilot may hold over an out-of-service NDB.  Refer to Advisory Circular 90-108, Use of Suitable RNAV  System on Conventional Routes and Procedures, dated  March 3, 2011 for additional guidance on the proper times  and procedures for substituting a RNAV system for means  of navigation.  An aircraft that has been cleared to a holding fix and  subsequently “cleared…approach,” normally does not  receive new routing. Even though clearance for the  approach may have been issued prior to the aircraft  reaching the holding fix, ATC would expect the pilot to  Courses  Traditional Courses  Equipment Requirements  Primary NAVAID  4-17 