The most likely time for a midair collision is when operating in the vicinity of an uncontrolled airport on a clear Sunday afternoon. I believe that the procedures used to enter a traffic pattern are one reason for these and other midair collisions.
Much of the guidance available regarding traffic patterns is in the Aeronautical Information Manual, and it is both sketchy and antiquated. This seems to prompt each instructor to teach his own way for entering the pattern at an uncontrolled airport. The result can be a disorganized traffic flow in the vicinity of an airport (particularly with respect to maneuvering onto the 45-degree entry leg).
The U.S. method of pattern entry is not used universally; nor is it the most efficient. In New Zealand, for example, pilots use "overhead joining procedures." This requires that a pilot approach the destination airport at an altitude of 500 feet above pattern altitude so that the airport is situated on the pilot's left. The pilot then circles the airport in a counterclockwise fashion until determining the runway in use and assessing other variables that could affect safety. As he does this, others joining this counterclockwise traffic flow above the pattern do so at the same altitude and fly in the same direction. This enables pilots approaching the airport to anticipate the actions of others in this overhead orbit.
In the vast majority of cases, pilots circling overhead determine that the runway in use requires a left traffic pattern, so they are already orbiting in the proper direction (counterclockwise). If it is determined that a right pattern is in use, arriving pilots must reverse course above pattern altitude so as to orbit in a clockwise direction.
The arriving pilot continues orbiting overhead until parallel to the landing runway on the non-traffic side of the pattern. He descends to traffic pattern altitude without conflicting with those flying downwind on the other side of the runway. He then turns crosswind over the departure end of the runway while determining that a high-performance aircraft (such as a Learjet) is not climbing rapidly toward him. (When such an aircraft is departing the active runway, the arriving pilot should turn crosswind earlier (nearer the center of the runway) to avoid conflict. Similarly, departing pilots climbing steeply must be on the alert for aircraft crossing the departure end of the runway at pattern altitude.
The arriving pilot is now heading perpendicular to the downwind leg at pattern altitude and should turn downwind with respect to other aircraft that might be there. Once this is done, he is in the pattern and can plan the remainder of his approach accordingly.
This method is not perfect; no system for entering a traffic pattern and mingling with other airplanes can be. But it offers some features that are more organized than the procedures we use, and each pilot better understands what is expected of him and what to expect of others. It also saves having to fly away from the airport for some lengthy and unspecified distance before maneuvering onto the 45-degree entry leg, which in and by itself offers a potential for conflict.
My purpose in discussing the New Zealand procedures here is to provide food for thought and to encourage the FAA and/or the aviation industry to improve on the pattern-entry procedures currently in use.
With respect to pattern altitude, a pet peeve is a lack of standardization. When I began flying in what now seems like the Dark Ages of aviation (1952), 800 feet agl was the standard pattern altitude for almost all airports. Today, pattern altitudes in my local flying area (Southern California), for example, vary from 600 feet agl (Santa Paula) to 1,700 feet agl for twins and 1,200 feet agl for singles (Santa Monica). (Pattern altitudes have been elevated in recent years because of noise-abatement considerations.)
Also, published pattern altitudes often are illogically expressed to the nearest foot. North Las Vegas, Reno, and Santa Ana, for example, have pattern altitudes of 3,003; 5,212; and 854 feet msl, respectively. Life would be simpler if they were 3,000; 5,200; and 900 feet, respectively.
Furthermore, a pilot should be able to determine pattern altitude for any given airport with a quick glance at his sectional or terminal area chart. All he should have to do is refer to airport elevation, add 800 feet, and round off to the nearest 100 feet. (Or, perhaps, a standard pattern altitude of 1,000 feet agl should be established.) The data block of airport information on the VFR chart could show exceptions in some easy-to-understand notation, such as "PA24," which would mean that the pattern altitude is 2,400 feet msl.
Currently, the only way to determine pattern altitude is to refer to an airport directory and search for the required information. This can be a dangerous distraction at a time when a pilot is diverting to and approaching a busy airport (and did not have the opportunity to plan his arrival prior to departure).
Current pattern-entry procedures were developed a half-century ago when there were many more airports and far fewer aircraft. More than enough time has passed to justify some improvements.
Additional traffic pattern guidance can be found in FARs 91.113, 91.126, and 91.127, as well as the AOPA Air Safety Foundation's Operations at Nontowered Airports Safety Advisor — available on request and on the Web ( www.aopa.org/asf/publications/sa08.pdf).
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