Airport Operations

aircraft have shown that vortices remain spaced a bit less than landing (since vortices settle and move laterally a wingspan apart, drifting with the wind, at altitudes greater near the ground, the vortex hazard may exist along than a wingspan from the ground. Tests have also shown that the runway and in the flight path, particularly in a the vortices sink at a rate of several hundred feet per minute, quartering tailwind), it is prudent to wait at least 2 slowing their descent and diminishing in strength with time minutes prior to a takeoff or landing. and distance behind the generating aircraft. • En route, it is advisable to avoid a path below and behind a large aircraft, and if a large aircraft is When the vortices of larger aircraft sink close to the ground observed above on the same track, change the aircraft (within 100 to 200 feet), they tend to move laterally over position laterally and preferably upwind. the ground at a speed of 2–3 knots. A crosswind decreases the lateral movement of the upwind vortex and increases Collision Avoidance the movement of the downwind vortex. A light quartering tailwind presents the worst case scenario as the wake Title 14 of the CFR part 91 has established right-of-way vortices could be all present along a significant portion of rules, minimum safe altitudes, and VFR cruising altitudes the final approach and extended centerline and not just in the to enhance flight safety. The pilot can contribute to collision touchdown zone as typically expected. avoidance by being alert and scanning for other aircraft. This is particularly important in the vicinity of an airport. Vortex Avoidance Procedures Effective scanning is accomplished with a series of short, The following procedures are in place to assist pilots in vortex regularly spaced eye movements that bring successive areas of avoidance in the given scenario. the sky into the central visual field. Each movement should not • Landing behind a larger aircraft on the same runway— exceed 10°, and each should be observed for at least 1 second stay at or above the larger aircraft’s approach to enable detection. Although back and forth eye movements flight path and land beyond its touchdown point. seem preferred by most pilots, each pilot should develop a [Figure 14-47A] scanning pattern that is most comfortable and then adhere to • Landing behind a larger aircraft on a parallel runway it to assure optimum scanning. Even if entitled to the right-of- closer than 2,500 feet—consider the possibility of drift way, a pilot should yield if another aircraft seems too close. and stay at or above the larger aircraft’s final approach flight path and note its touchdown point. [Figure 14-47B] Clearing Procedures The following procedures and considerations are in place to • Landing behind a larger aircraft on crossing runway— assist pilots in collision avoidance under various situations: cross above the larger aircraft’s flight path. • Landing behind a departing aircraft on the same • Before takeoff—prior to taxiing onto a runway or runway—land prior to the departing aircraft’s landing area in preparation for takeoff, pilots should rotating point. scan the approach area for possible landing traffic, • Landing behind a larger aircraft on a crossing executing appropriate maneuvers to provide a clear runway—note the aircraft’s rotation point and, if that view of the approach areas. point is past the intersection, continue and land prior • Climbs and descents—during climbs and descents in to the intersection. If the larger aircraft rotates prior flight conditions that permit visual detection of other to the intersection, avoid flight below its flight path. traffic, pilots should execute gentle banks left and right at a Abandon the approach unless a landing is ensured well frequency that permits continuous visual scanning of the before reaching the intersection. [Figure 14-47C] airspace. • Departing behind a large aircraft—rotate prior to the • Straight and level—during sustained periods of large aircraft’s rotation point and climb above its climb straight-and-level flight, a pilot should execute path until turning clear of the wake. appropriate clearing procedures at periodic intervals. • For intersection takeoffs on the same runway— • Traffic patterns—entries into traffic patterns while be alert to adjacent larger aircraft operations, descending should be avoided. particularly upwind of the runway of intended use. • Traffic at VOR sites—due to converging traffic, If an intersection takeoff clearance is received, avoid sustained vigilance should be maintained in the headings that cross below the larger aircraft’s path. vicinity of VORs and intersections. • If departing or landing after a large aircraft executing • Training operations—vigilance should be maintained and a low approach, missed approach, or touch-and-go clearing turns should be made prior to a practice maneuver. During instruction, the pilot should be asked to verbalize the clearing procedures (call out “clear left, 14-28 right, above, and below”).