Reversal fix may  be specified  Complete in “remain  within” distance  The 45°/180° procedure turn  Base turn The 80°/260° procedure turn  Racetrack procedure  Specified time or depicted fix 1 minute  Reversal fix may  be specified  Complete in “remain  within” distance  1 min 15 sec - C a t C,D&E  Figure 4-32. Course reversal methods.  2 NM outside the approach gate. Exceptions include the  following situations, but do not apply to RNAV aircraft  being vectored for a GPS or RNAV approach:  the published feeder route to the IAF or from the IAF as  appropriate. The aircraft would not be expected to overfly  and return to the IAF or feeder route.  For aircraft operating on unpublished routes, an altitude  is assigned to maintain until the aircraft is established  on a segment of a published route or IAP. (Example:  “Maintain 2,000 until established on the final approach  course outbound, cleared VOR/DME runway 12.”) The FAA  definition of established on course requires the aircraft  to be established on the route centerline. Generally, the  controller assigns an altitude compatible with glideslope/  glidepath intercept prior to being cleared for the approach.  In the NAS, there are approximately 1,105 VOR stations, 916  NDB stations, and 1,194 ILS installations, including 25 LOC- type directional aids (LDAs), 11 simplified directional facilities  (SDFs), and 235 LOC only facilities. As time progresses, it is  the intent of the FAA to reduce navigational dependence on  VOR, NDB, and other ground-based NAVAIDs and, instead,  to increase the use of satellite-based navigation.  To expedite the use of RNAV procedures for all instrument  pilots, the FAA has begun an aggressive schedule to  develop RNAV procedures. As of 2010, the number of  RNAV/ GPS approaches published in the NAS numbered  In the absence of radar vectors, an instrument approach  begins at an IAF. An aircraft that has been cleared to  a holding fix that, prior to reaching that fix, is issued a  clearance for an approach, but not issued a revised routing,  such as, “proceed direct to…” is expected to proceed via the  last assigned route, a feeder route if one is published on  the approach chart, and then to commence the approach  as published. If, by following the route of flight to the  holding fix, the aircraft would overfly an IAF or the fix  associated with the beginning of a feeder route to be used,  the aircraft is expected to commence the approach using  Nonradar Environment  • When the reported ceiling is at least 500 feet above  the MVA/MIA and the visibility is at least 3 SM (may be a pilot report (PIREP) if no weather is reported for  the airport), aircraft may be vectored to intercept the final approach course closer than 2 NM outside the approach gate but no closer than the approach  gate.  • If specifically requested by the pilot, aircraft may be vectored to intercept the final approach course inside the approach gate but no closer than the FAF.  Types of Approaches  4-54