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6/17/21 

AIM 

judgment, places the aircraft in unsafe proximity to 
terrain, obstructions or other aircraft. The provision 
of this service is contingent upon the capability of the 
controller to have an awareness of a situation 
involving unsafe proximity to terrain, obstructions 
and uncontrolled aircraft. The issuance of a safety 
alert cannot be mandated, but it can be expected on a 
reasonable, though intermittent basis. Once the alert 
is issued, it is solely the pilot’s prerogative to 
determine what course of action, if any, to take. This 
procedure is intended for use in time critical 
situations where aircraft safety is in question. 
Noncritical situations should be handled via the 
normal traffic alert procedures. 

a.  Terrain or Obstruction Alert 

1. 

Controllers will immediately issue an alert to 

the pilot of an aircraft under their control when they 
recognize that the aircraft is at an altitude which, in 
their judgment, may be in an unsafe proximity to 
terrain/obstructions. The primary method of detect-
ing 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 authoriza-

tion to proceed in accordance with such radar 
navigational assistance does not constitute authoriza-
tion 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. 

Services Available to Pilots 

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