Index   148 -- Page 149 -- 150

12/10/15                                                                                                       AIM



                             Section 2. Controlled Airspace

3-2-1. General                                              into Class B, Class C, or Class D airspace. The pilot
                                                            retains this responsibility when receiving ATC radar
   a. Controlled Airspace. A generic term that              advisories. (See 14 CFR Part 91.)
covers the different classification of airspace
(Class A, Class B, Class C, Class D, and Class E               e. Traffic Advisories. Traffic advisories will be
airspace) and defined dimensions within which air           provided to all aircraft as the controller's work
traffic control service is provided to IFR flights and      situation permits.
to VFR flights in accordance with the airspace                f. Safety Alerts. Safety Alerts are mandatory
classification. (See FIG 3-2-1.)                            services and are provided to ALL aircraft. There are
                                                            two types of Safety Alerts:
   b. IFR Requirements. IFR operations in any
class of controlled airspace requires that a pilot must         1. Terrain/Obstruction Alert. A Terrain/
file an IFR flight plan and receive an appropriate ATC      Obstruction Alert is issued when, in the controller's
clearance.                                                  judgment, an aircraft's altitude places it in unsafe
                                                            proximity to terrain and/or obstructions; and
  c. IFR Separation. Standard IFR separation is
provided to all aircraft operating under IFR in                  2. Aircraft Conflict/Mode C Intruder Alert.
controlled airspace.                                         An Aircraft Conflict/Mode C Intruder Alert is issued
                                                            if the controller observes another aircraft which
  d. VFR Requirements. It is the responsibility of          places it in an unsafe proximity. When feasible, the
the pilot to ensure that ATC clearance or radio             controller will offer the pilot an alternative course of
communication requirements are met prior to entry           action.
                                                     FIG 3-2-1
                                                 Airspace Classes




           FL 600                                   CLASS A
           18,000 MSL
           14,500 MSL                                            CLASS E


                                      CLASS B
                                                                 CLASS C

                                                                                           CLASS
                                                                                           CL ASS D
            Nontowered     700 AGL                                             1,200 AGL
              Airport
                         CLASS G                   CLASS G                    CLASS G



                                              MSL - mean sea level
                                              AGL - above ground level
                                              FL - flight level




Controlled Airspace                                                                                          3-2-1