11/3/22
AIM
(a)
Distance and direction with respect to a
fix;
(b)
Direction in which the target is proceed-
ing; and
(c)
Type of aircraft and altitude if known.
EXAMPLE
−
Traffic 8 miles south of the airport northeast
−
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
−
1
−
1
Induced Error in Position of Traffic
WIND
TRACK
TRACK
(A)
(B)
EXAMPLE
−
In FIG 4
−
1
−
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
−
1
−
2
Induced Error in Position of Traffic
TRACK
(C)
(D)
WIND
TRACK
EXAMPLE
−
In FIG 4
−
1
−
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.
4
−
1
−
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
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
Services Available to Pilots
4
−
1
−
11