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(s) within the TRSA become(s) 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.
Air Traffic Control and the National
Airspace System
The primary purpose of the ATC system is to prevent a
collision between aircraft operating in the system and to
organize and expedite the flow of traffic. In addition to
its primary function, the ATC system has the capability to
provide (with certain limitations) additional services. The
ability to provide additional services is limited by many
factors, such as the volume of traffic, frequency congestion,
quality of radar, controller workload, higher priority duties,
and the pure physical inability to scan and detect those
situations that fall in this category. It is recognized that these
services cannot be provided in cases in which the provision
of services is precluded by the above factors.
Consistent with the aforementioned conditions, controllers
shall provide additional service procedures to the extent
permitted by higher priority duties and other circumstances.
The provision of additional services is not optional on the
part of the controller, but rather is required when the work
situation permits. Provide ATC service in accordance with
the procedures and minima in this order except when:
1. A deviation is necessary to conform to ICAO
Documents, National Rules of the Air, or special
agreements where the United States provides ATC
service in airspace outside the country and its
possessions
2. Other procedures/minima are prescribed in a letter of
agreement, FAA directive, or a military document
3. A deviation is necessary to assist an aircraft when an
emergency has been declared
Coordinating the Use of Airspace
ATC is responsible for ensuring that the necessary
coordination has been accomplished before allowing an
aircraft under their control to enter another controller’s area
of jurisdiction.
Before issuing control instructions directly or relaying
through another source to an aircraft that is within another
controller’s area of jurisdiction that will change that
aircraft’s heading, route, speed, or altitude, ATC ensures
that coordination has been accomplished with each of the
controllers listed below whose area of jurisdiction is affected
by those instructions unless otherwise specified by a letter
of agreement or a facility directive:
1. The controller within whose area of jurisdiction the
control instructions are issued
2. The controller receiving the transfer of control
3. Any intervening controller(s) through whose area of
jurisdiction the aircraft will pass
If ATC issues control instructions to an aircraft through a
source other than another controller (e.g., Aeronautical Radio,
Incorporated (ARINC), FSS, another pilot), they ensure that
the necessary coordination has been accomplished with any
controllers listed above, whose area of jurisdiction is affected
by those instructions unless otherwise specified by a letter
of agreement or a facility directive.
Operating in the Various Types of Airspace
It is important that pilots be familiar with the operational
requirements for each of the various types or classes of
airspace. Subsequent sections cover each class in sufficient
detail to facilitate understanding regarding weather, type of
pilot certificate held, and equipment required.
Basic VFR Weather Minimums
No pilot may operate an aircraft under basic VFR when the
flight visibility is less, or at a distance from clouds that is
less, than that prescribed for the corresponding altitude and
class of airspace. [Figure 15-8] Except as provided in 14 CFR
part 91, section 91.157, “Special VFR Weather Minimums,”
Distance from CloudsAirspace Flight Visibility
Basic VFR Weather Minimums
Not applicable Not applicable
3 statute miles Clear of clouds
3 statute miles 1,000 feet above
500 feet below
2,000 feet horizontal
3 statute miles 1,000 feet above
500 feet below
2,000 feet horizontal
5 statute miles 1,000 feet above
1,000 feet below
1 statute mile horizontal
3 statute miles 1,000 feet above
500 feet below
2,000 feet horizontal
Day, except as provided in section 91.155(b) 1 statute mile Clear of clouds
Night, except as provided in section 91.155(b) 3 statute miles 1,000 feet above
500 feet below
2,000 feet horizontal
Day 1 statute mile 1,000 feet above
500 feet below
2,000 feet horizontal
Night 3 statute miles 1,000 feet above
500 feet below
2,000 feet horizontal
5 statute miles 1,000 feet above
1,000 feet below
1 statute mile horizontal
1,200 feet or less
above the surface
(regardless of
MSL altitude).
More than 1,200
feet above the
surface but less
than 10,000 feet
MSL.
More than 1,200
feet above the
surface and at or
above 10,000 feet
MSL.
At or above
10,000 feet MSL
Less than
10,000 feet MSL
Class
A
Class
B
Class
C
Class
D
Class
E
Class
G
Figure 15-8. Visual flight rule weather minimums.
no person may operate an aircraft beneath the ceiling under
VFR within the lateral boundaries of controlled airspace
designated to the surface for an airport when the ceiling is
less than 1,000 feet. Additional information can be found in
14 CFR part 91, section 91.155(c).
Operating Rules and Pilot/Equipment Requirements
The safety of flight is a top priority of all pilots and the
responsibilities associated with operating an aircraft
should always be taken seriously. The air traffic system
maintains a high degree of safety and efficiency with strict
regulatory oversight of the FAA. Pilots fly in accordance
with regulations that have served the United States well, as
evidenced by the fact that the country has the safest aviation
system in the world.
All aircraft operating in today’s National Airspace System
(NAS) has complied with the CFR governing its certification
and maintenance; all pilots operating today have completed
rigorous pilot certification training and testing. Of equal
importance is the proper execution of preflight planning,
aeronautical decision-making (ADM) and risk management.
ADM involves a systematic approach to risk assessment
and stress management in aviation, illustrates how personal
attitudes can influence decision-making, and how those
attitudes can be modified to enhance safety in the flight
deck. More detailed information regarding ADM and
risk mitigation can be found in Chapter 2, “Aeronautical
Decision-Making.”