both the pilot and controller know precisely what altitude  is to be flown and precisely where descent to appropriate  minimum altitudes or step-down altitudes can begin.  Most aircraft are vectored onto a localizer or final approach  course between an intermediate fix and the approach gate.  These aircraft normally are told to maintain an altitude until  established on a segment of the approach.  When an aircraft is assigned a route that is not a published  segment of an approach, the controller must issue an  altitude to maintain until the aircraft is established on a  published segment of the approach. [Figure 3-21] Assume  the aircraft is established on the final approach course  beyond the approach segments, 8 NM from Alpha at 6,000  feet. The minimum vectoring altitude for this area is 4,000  feet. “Eight miles from Alpha. Cross Alpha at or above four  thousand. Cleared ILS runway three six approach.”  If an aircraft is not established on a segment of a published  approach and is not conducting a radar approach,  ATC assigns an altitude to maintain until the aircraft  is established on a segment of a published route or  instrument approach procedure. [Figure 3-22]  The aircraft is being vectored to a published segment of the  ILS final approach course, 3 NM from Alpha at 4,000 feet.  The minimum vectoring altitude for this area is 4,000 feet.  “Three miles from Alpha. Turn left heading two one zero.  Maintain four thousand until established on the localizer.  The ATC assigned altitude ensures IFR obstruction  clearance from the point at which the approach clearance  is issued until established on a segment of a published  route or instrument approach procedure.  Cleared ILS runway one eight approach.”  ATC tries to make frequency changes prior to passing the  FAF, although when radar is used to establish the FAF, ATC  informs the pilot to contact the tower on the local control  frequency after being advised that the aircraft is over the  fix. For example, “Three miles from final approach fix. Turn  left heading zero one zero. Maintain two thousand until  established on the localizer. Cleared ILS runway three six  approach. I will advise when over the fix.”  “Over final approach fix. Contact tower one-one eight  point one.”  It is important to note an example of additional resources  that are helpful for arrivals, especially into unfamiliar  airports requiring special pilot or navigation qualifications.  The operating rules governing domestic and flag air  carriers require pilots in command to be qualified over  the routes and into airports where scheduled operations  are conducted, including areas, routes, and airports in  which special pilot qualifications or special navigation  qualifications are needed. For Part 119 certificate holders  Special Airport Qualification  Special Airports  Kodiak, AK  Petersburg, AK  Cape Newenham AFS, AK  Washington, DC (National)  Shenandoah Valley, VA  (Stanton-Waynesboro-Harrisonburg)  Aspen, CO  Gunnison, CO  Missoula, MT  Jackson Hole, WY  Hailey, ID (Friedman Memorial)  Hayden, Yampa Valley, CO  Lihue, Kauai, HI  Ontario, CA  Comments  Airport is surrounded by mountainous terrain. Any go-around beyond ILS or GCA  MAP will not provide obstruction clearance.  Mountainous terrain in immediate vicinity of airport, all quadrants.  Runway located on mountain slope with high gradient factor; nonstandard  instrument approach.  Special arrival/departure procedures.  Mountainous terrain.  High terrain; special procedures.  VOR only; uncontrolled; numerous obstructions in airport area; complete departure  procedures.  Mountainous terrain; special procedures.  Mountainous terrain; all quadrants; complex departure procedures.  Mountainous terrain; special arrival/departure procedures.  Mountainous terrain; no control tower; special engine-out procedures for certain  large aircraft.  High terrain; mountainous to 2,300 feet within 3 miles of the localizer.  Mountainous terrain and extremely limited visibility in haze conditions.  Figure 3-27. Special airports and comments.  3-26 