CHAPTER 8. The National Airspace System

Parachute Jump Areas

Parachute jump areas are published in the Airport/ Facility Directory (A/FD). Sites that are used frequently are depicted on sectional charts. Each pilot should listen to the appropriate airport radio frequency for parachute operations and be alert for aircraft which might be conducting parachute operations.

Other Airspace Areas

Other airspace areas is a general term referring to the majority of the remaining airspace. It includes:

  • Airport advisory areas
  • Military training routes (MTRs)
  • Temporary fl ight restrictions (TFRs)
  • Terminal Radar Service Areas
  • National security areas

Local Airport Advisory

A local airport advisory is an area within 10 statute miles (SM) of an airport where a control tower is not operating, but where a fl ight service station (FSS) is located. At these locations, the FSS provides advisory service to arriving and departing aircraft. See AIM section 3-5-1 for more information on using the local airport fl ight station services.

Military Training Routes (MTRs)

National security depends largely on the deterrent effect of our airborne military forces. To be profi cient, the military services must train in a wide range of airborne tactics. One phase of this training involves “low level” combat tactics. The required maneuvers and high speeds are such that they may occasionally make the see-and-avoid aspect of VFR fl ight more diffi cult without increased vigilance in areas containing such operations. In an effort to ensure the greatest practical level of safety for all fl ight operations, the Military Training Route (MTR) program was conceived.

These routes are usually established below 10,000 feet MSL for operations at speeds in excess of 250 knots. Some route segments may be defi ned at higher altitudes for purposes of route continuity. Routes are identifi ed as IFR (IR), and VFR (VR), followed by a number. MTRs with no segment above 1,500 feet AGL are identifi ed by four numeric characters (e.g., IR1206, VR1207). MTRs that include one or more segments above 1,500 feet AGL are identifi ed by three numeric characters (e.g., IR206, VR207). IFR Low Altitude En Route Charts depict all IR routes and all VR routes that accommodate operations above 1,500 feet AGL. IR routes are conducted in accordance with IFR regardless of weather conditions.

MTRs are usually indicated with a gray line on the sectional chart. A WSC aircraft pilot fl ying in the area of VRs or IRs should question the briefer during the weather brief to fi nd out if any of the routes are in use, and a possible time frame for opening and closing. While it is true that the WSC aircraft pilot has the right of way, the WSC aircraft will generally come out worse in a midair confl ict with a fast-moving military aircraft. MTRs, such as the example depicted in Figure 8-17, are also further defi ned on sectional charts.

Temporary Flight Restrictions (TFRs)

TFRs are put into effect when traffi c in the airspace would endanger or hamper air or ground activities in the designated area. For example, a forest fi re, chemical accident, fl ood, or disaster-relief effort could warrant a TFR, which would be issued as a Notice to Airmen (NOTAM). The NOTAM begins with the phrase “FLIGHT RESTRICTIONS” followed by the location, effective time period, area defi ned in statute miles, and altitudes affected, which aircraft fl ying in the area must avoid. The NOTAM also contains the FAA coordination facility and telephone number, the reason for the restriction, and any other information deemed appropriate. The pilot should check NOTAMs as part of fl ight planning.

The reasons for establishing a temporary restriction are to:

  • Protect persons and property in the air or on the surface from an existing or imminent hazard;
  • Provide a safe environment for the operation of disaster relief aircraft;
  • Prevent unsafe congestion of sightseeing aircraft above an incident or event, which may generate a high degree of public interest;
  • Protect declared national disasters for humanitarian reasons;
  • Protect the President, Vice President, or other public fi gures; and
  • Provide a safe environment for space agency operations.

It is a pilot’s responsibility to be aware of TFRs in his or her proposed area of fl ight. One way to check is to visit the FAA website,, and verify that there is not a TFR in the area. Another resource is to ask the fl ight briefer at 800-WX-BRIEF during the prefl ight briefi ng.

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