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AIM 

4/20/23

 

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14

Services Available to Pilots

terrain/obstructions. The primary method of detecting unsafe proximity is through Mode C automatic altitude
reports.

EXAMPLE

Low altitude alert Cessna Three Four Juliet, check your altitude immediately. And if the aircraft is not yet on final approach,
the MVA (MEA/MIA/MOCA) in your area is six thousand.

2.

Most En Route and Terminal radar facilities have an automated function which, if operating, alerts

controllers when a tracked Mode C equipped aircraft under their control is below or is predicted to be below a
predetermined minimum safe altitude. This function, called Minimum Safe Altitude Warning (MSAW), is
designed solely as a controller aid in detecting potentially unsafe aircraft proximity to terrain/obstructions. The
radar facility will, when MSAW is operating, provide MSAW monitoring for all aircraft with an operating Mode
C altitude encoding transponder that are tracked by the system and are:

(a)

Operating on an IFR flight plan; or

(b)

Operating VFR and have requested MSAW monitoring.

NOTE

Pilots operating VFR may request MSAW monitoring if their aircraft are equipped with Mode C transponders.

EXAMPLE

Apache Three Three Papa request MSAW monitoring.

3.

Due to the lack of terrain and obstacle clearance data, accurate automation databases may not be available

for providing MSAW information to aircraft overflying Mexico and Canada. Air traffic facilities along the
United States/Mexico/Canada borders may have MSAW computer processing inhibited where accurate terrain
data is not available.

b. Aircraft Conflict Alert.

1.

Controllers will immediately issue an alert to the pilot of an aircraft under their control if they are aware

of another aircraft which is not under their control, at an altitude which, in the controller’s judgment, places both
aircraft in unsafe proximity to each other. With the alert, when feasible, the controller will offer the pilot the
position of the traffic if time permits and an alternate course(s) of action. Any alternate course(s) of action the
controller may recommend to the pilot will be predicated only on other traffic being worked by the controller.

EXAMPLE

American Three, traffic alert, (position of traffic, if time permits), advise you turn right/left heading (degrees) and/or
climb/descend to (altitude) immediately.

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17. Radar Assistance to VFR Aircraft

a.

Radar equipped FAA ATC facilities provide radar assistance and navigation service (vectors) to VFR

aircraft provided the aircraft can communicate with the facility, are within radar coverage, and can be radar
identified.

b.

Pilots should clearly understand that authorization to proceed in accordance with such radar navigational

assistance does not constitute authorization for the pilot to violate CFRs. In effect, assistance provided is on the
basis that navigational guidance information issued is advisory in nature and the job of flying the aircraft safely,
remains with the pilot.

c.

In many cases, controllers will be unable to determine if flight into instrument conditions will result from

their instructions. To avoid possible hazards resulting from being vectored into IFR conditions, pilots should
keep controllers advised of the weather conditions in which they are operating and along the course ahead.

d.

Radar navigation assistance (vectors) may be initiated by the controller when one of the following

conditions exist:

1.

The controller suggests the vector and the pilot concurs.

2.

A special program has been established and vectoring service has been advertised.