AIM 

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

reports. 

EXAMPLE

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Low altitude alert Cessna Three Four Juliett, 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

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

EXAMPLE

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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

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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. 

Services Available to Pilots 

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