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Pilot's Handbook of Aeronautical Knowledge
Airport Operations

Collision Avoidance

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Pilot's Handbook of Aeronautical Knowledge



Table of Contents

Chapter 1, Introduction To Flying
Chapter 2, Aircraft Structure
Chapter 3, Principles of Flight
Chapter 4, Aerodynamics of Flight
Chapter 5, Flight Controls
Chapter 6, Aircraft Systems
Chapter 7, Flight Instruments
Chapter 8, Flight Manuals and Other Documents
Chapter 9, Weight and Balance
Chapter 10, Aircraft Performance
Chapter 11, Weather Theory
Chapter 12, Aviation Weather Services
Chapter 13, Airport Operation
Chapter 14, Airspace
Chapter 15, Navigation
Chapter 16, Aeromedical Factors
Chapter 17, Aeronautical Decision Making




Vortex behavior.
Figure 13-21. Vortex behavior.

When the vortices of larger aircraft sink close to the ground
(within 100 to 200 feet), they tend to move laterally over
the ground at a speed of 2–3 knots. A crosswind decreases
the lateral movement of the upwind vortex and increases the
movement of the downwind vortex. A tailwind condition can
move the vortices of the preceding aircraft forward into the
touchdown zone.

Vortex Avoidance Procedures
• Landing behind a larger aircraft on the same runway—
stay at or above the larger aircraft's approach
flightpath and land beyond its touchdown point.
• Landing behind a larger aircraft on a parallel runway
closer than 2,500 feet—consider the possibility of drift
and stay at or above the larger aircraft's final approach
flightpath and note its touch down point.
• Landing behind a larger aircraft on crossing runway—
cross above the larger aircraft's flightpath
• Landing behind a departing aircraft on the same
runway—land prior to the departing aircraft's rotating
• Landing behind a larger aircraft on a crossing
runway—note the aircraft's rotation point and, if that
point is past the intersection, continue and land prior
to the intersection. If the larger aircraft rotates prior
to the intersection, avoid flight below its flightpath
Abandon the approach unless a landing is ensured
well before reaching the intersection.
• Departing behind a large aircraft—rotate prior to the
large aircraft's rotation point and climb above its climb
path until turning clear of the wake.
• For intersection takeoffs on the same runway—be
alert to adjacent larger aircraft operations, particularly
upwind of the runway of intended use. If an intersection
takeoff clearance is received, avoid headings that cross
below the larger aircraft's path.

• If departing or landing after a large aircraft executing
a low approach, missed approach, or touch and go
landing (since vortices settle and move laterally
near the ground, the vortex hazard may exist along
the runway and in the flightpath, particularly in a
quartering tailwind), it is prudent to wait at least 2
minutes prior to a takeoff or landing.
• En route it is advisable to avoid a path below and
behind a large aircraft, and if a large aircraft is
observed above on the same track, change the aircraft
position laterally and preferably upwind.

Collision Avoidance

14 CFR part 91 has established right-of-way rules, minimum
safe altitudes, and VFR cruising altitudes to enhance flight
safety. The pilot can contribute to collision avoidance by
being alert and scanning for other aircraft. This is particularly
important in the vicinity of an airport.

Effective scanning is accomplished with a series of short,
regularly spaced eye movements that bring successive areas
of the sky into the central visual field. Each movement
should not exceed 10°, and each should be observed for at
least 1 second to enable detection. Although back and forth
eye movements seem preferred by most pilots, each pilot
should develop a scanning pattern that is most comfortable
and then adhere to it to assure optimum scanning. Even if
entitled to the right-of-way, a pilot should yield if another
aircraft seems too close.