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AIM

10/12/17

4−4−11

ATC Clearances and Aircraft Separation

Although many pilots seem to prefer the method of

horizontal back−and−forth scanning every pilot

should develop a scanning pattern that is not only

comfortable but assures optimum effectiveness.

Pilots should remember, however, that they have a

regulatory responsibility (14 CFR Section 91.113(a))

to see and avoid other aircraft when weather

conditions permit.

4−4−15. Use of Visual Clearing Procedures

a. Before Takeoff. Prior to taxiing onto a runway

or landing area in preparation for takeoff, pilots

should scan the approach areas for possible landing

traffic and execute the appropriate clearing maneu-

vers to provide them a clear view of the approach

areas.

b. Climbs and Descents. During climbs and

descents in flight conditions which permit visual

detection of other traffic, pilots should execute gentle

banks, left and right at a frequency which permits

continuous visual scanning of the airspace about

them.

c. Straight and Level. Sustained periods of

straight and level flight in conditions which permit

visual detection of other traffic should be broken at

intervals with appropriate clearing procedures to

provide effective visual scanning.

d. Traffic Pattern. Entries into traffic patterns

while descending create specific collision hazards

and should be avoided.

e. Traffic at VOR Sites. All operators should

emphasize the need for sustained vigilance in the

vicinity of VORs and airway intersections due to the

convergence of traffic.

f. Training Operations. Operators of pilot train-

ing programs are urged to adopt the following

practices:

1. Pilots undergoing flight instruction at all

levels should be requested to verbalize clearing

procedures (call out “clear” left, right, above, or

below) to instill and sustain the habit of vigilance

during maneuvering.

2. High−wing airplane. Momentarily raise the

wing in the direction of the intended turn and look.

3. Low−wing airplane. Momentarily lower

the wing in the direction of the intended turn and look.

4. Appropriate clearing procedures should

precede the execution of all turns including

chandelles, lazy eights, stalls, slow flight, climbs,

straight and level, spins, and other combination

maneuvers.

4−4−16. Traffic Alert and Collision

Avoidance System (TCAS I & II)

a. TCAS I provides proximity warning only, to

assist the pilot in the visual acquisition of intruder

aircraft. No recommended avoidance maneuvers are

provided nor authorized as a direct result of a TCAS I

warning. It is intended for use by smaller commuter

aircraft holding 10 to 30 passenger seats, and general

aviation aircraft.

b. TCAS II provides traffic advisories (TAs) and

resolution advisories (RAs). Resolution advisories

provide recommended maneuvers in a vertical

direction (climb or descend only) to avoid conflicting

traffic. Airline aircraft, and larger commuter and

business aircraft holding 31 passenger seats or more,

use TCAS II equipment.

1. Each pilot who deviates from an ATC

clearance in response to a TCAS II RA must notify

ATC of that deviation as soon as practicable and

expeditiously return to the current ATC clearance

when the traffic conflict is resolved.

2. Deviations from rules, policies, or clearances

should be kept to the minimum necessary to satisfy a

TCAS II RA.

3. The serving IFR air traffic facility is not

responsible to provide approved standard IFR

separation to an aircraft after a TCAS II RA maneuver

until one of the following conditions exists:

(a) The aircraft has returned to its assigned

altitude and course.

(b) Alternate ATC instructions have been

issued.

c. TCAS does not alter or diminish the pilot’s basic

authority and responsibility to ensure safe flight.

Since TCAS does not respond to aircraft which are

not transponder equipped or aircraft with a

transponder failure, TCAS alone does not ensure safe

separation in every case.