AIM

4/20/23

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13

Services Available to Pilots

(c)

Type of aircraft and altitude if known.

EXAMPLE

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Traffic 8 miles south of the airport northeast

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bound, (type aircraft and altitude if known).

d.

The examples depicted in the following figures point out the possible error in the position of this traffic

when it is necessary for a pilot to apply drift correction to maintain this track. This error could also occur in the
event a change in course is made at the time radar traffic information is issued.

FIG 4

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Induced Error in Position of Traffic

TRACK

(A)

(B)

WIND

TRACK

EXAMPLE

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In FIG 4

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1 traffic information would be issued to the pilot of aircraft “A” as 12 o’clock. The actual position of the traffic

as seen by the pilot of aircraft “A” would be 2 o’clock. Traffic information issued to aircraft “B” would also be given as
12 o’clock, but in this case, the pilot of “B” would see the traffic at 10 o’clock.

FIG 4

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Induced Error in Position of Traffic

TRACK

(C)

(D)

WIND

TRACK

EXAMPLE

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In FIG 4

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2 traffic information would be issued to the pilot of aircraft “C” as 2 o’clock. The actual position of the traffic

as seen by the pilot of aircraft “C” would be 3 o’clock. Traffic information issued to aircraft “D” would be at an 11 o’clock
position. Since it is not necessary for the pilot of aircraft “D” to apply wind correction (crab) to remain on track, the actual
position of the traffic issued would be correct. Since the radar controller can only observe aircraft track (course) on the radar
display, traffic advisories are issued accordingly, and pilots should give due consideration to this fact when looking for
reported traffic.

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16. Safety Alert

A safety alert will be issued to pilots of aircraft being controlled by ATC if the controller is aware the aircraft
is at an altitude which, in the controller’s 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