In addition to controlled, uncontrolled, and special use airspace, the National Airspace System includes several other designated airspace areas and operating environments. These areas support military activities, security requirements, traffic management, parachute operations, and other specialized aviation functions. Pilots should be familiar with these areas and any associated operating procedures before flight.
Other airspace areas are designated to support specific aviation activities and services within the National Airspace System. They include:
- Local airport advisory (LAA)
- Military training routes (MTRs)
- Temporary flight restrictions (TFRs)
- Parachute jump aircraft operations
- Published VFR routes
- Terminal radar service areas (TRSAs)
- National security areas (NSAs)
In addition to these airspace areas, pilots should be familiar with several special operating environments and security-related procedures, including:
- Air Defense Identification Zones (ADIZs) and Defense VFR (DVFR) flight plan requirements
- Aircraft intercept procedures and the use of 121.5 MHz for emergency communications
- Flight Restricted Zones (FRZs) in the vicinity of the U.S. Capitol and White House
- Special Awareness Training required by 14 CFR § 91.161 for VFR operations within 60 NM of the Washington, DC VOR/DME
- Wildlife Areas, Wilderness Areas, and National Parks, where pilots are requested to maintain at least 2,000 feet AGL
- National Oceanic and Atmospheric Administration (NOAA) Marine Areas, where pilots are requested to maintain at least 2,000 feet AGL
- Tethered balloons used for observation and weather data collection that may extend to altitudes of 60,000 feet
Local Airport Advisory (LAA)
An advisory service provided by Flight Service Station (FSS) facilities, which are located at the airport, using a discrete ground-to-air frequency or the tower frequency when the tower is closed. LAA services include local airport advisories, automated weather reporting with voice broadcasting, and a continuous Automated Surface Observing System (ASOS)/Automated Weather Observing Station (AWOS) data display, other continuous direct reading instruments, or manual observations available to the specialist.
Military Training Routes (MTRs)
MTRs are routes used by military aircraft to maintain proficiency in tactical flying. These routes are usually established below 10,000 feet MSL for operations at speeds in excess of 250 knots. Some route segments may be defined at higher altitudes for purposes of route continuity. Routes are identified as IFR (IR) and VFR (VR), followed by a number. [Figure 1]
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| Figure 1. Military training route (MTR) chart symbols |
MTRs with no segment above 1,500 feet AGL are identified by four number characters (e.g., IR1206, VR1207). MTRs that include one or more segments above 1,500 feet AGL are identified by three number 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. VFR sectional charts depict military training activities, such as IR, VR, MOA, restricted area, warning area, and alert area information.
Temporary Flight Restrictions (TFRs)
A flight data center (FDC) Notice to Airmen (NOTAM) is issued to designate a TFR. The NOTAM begins with the phrase “FLIGHT RESTRICTIONS” followed by the location of the temporary restriction, effective time period, area defined in statute miles, and altitudes affected. 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 the NOTAMs as part of flight planning.
Some of the purposes for establishing a TFR are:
- 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 an unsafe congestion of sightseeing aircraft above an incident or event that may generate a high degree of public interest.
- Protect declared national disasters for humanitarian reasons in the State of Hawaii.
- Protect the President, Vice President, or other public figures.
- Provide a safe environment for space agency operations.
Since the events of September 11, 2001, the use of TFRs has become much more common. There have been a number of incidents of aircraft incursions into TFRs that have resulted in pilots undergoing security investigations and certificate suspensions. It is a pilot’s responsibility to be aware of TFRs in their proposed area of flight. One way to check is to visit the FAA TFR website and verify that no TFR exists in the proposed area of flight.
Parachute Jump Aircraft Operations
Parachute jump aircraft operations are published in the Chart Supplement U.S. (formerly Airport/Facility Directory). Sites that are used frequently are depicted on sectional charts.
Published VFR Routes
Published VFR routes are for transitioning around, under, or through some complex airspace. Terms such as VFR flyway, VFR corridor, Class B airspace VFR transition route, and terminal area VFR route have been applied to such routes.
These routes are generally found on VFR terminal area planning charts.
Terminal Radar Service Areas (TRSAs)
TRSAs are areas where participating pilots can receive additional radar services. The purpose of the service is to provide separation between all IFR operations and participating VFR aircraft.
The primary airport within a TRSA is typically surrounded by Class D airspace. The remaining portion of the TRSA overlies other controlled airspace, which is normally Class E airspace beginning at 700 or 1,200 feet and established to transition to/from the en route/terminal environment. TRSAs are depicted on VFR sectional charts and terminal area charts with a solid black line and altitudes for each segment. The Class D portion is charted with a blue segmented line. Participation in TRSA services is voluntary; however, pilots operating under VFR are encouraged to contact the radar approach control and take advantage of TRSA service.
National Security Areas (NSAs)
NSAs consist of airspace of defined vertical and lateral dimensions established at locations where there is a requirement for increased security and safety of ground facilities. Flight in NSAs may be temporarily prohibited by regulation under the provisions of Title 14 of the Code of Federal Regulations (14 CFR) Part 99, and prohibitions are disseminated via NOTAM. Pilots are requested to voluntarily avoid flying through these depicted areas.
Quick Review: Other Airspace Areas
How can a pilot decode the altitude limits of a Military Training Route (MTR) from its identifier?
What are the legal implications and administrative steps for checking a TFR?
What is a Terminal Radar Service Area (TRSA) and is VFR participation mandatory?
What conservation rules apply to flying over national parks, wilderness areas, and wildlife refuges?
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