It is easy to feel relatively secure in dealing with known aviation risks.  We can plan for potential hazards such as bad weather or systems failures and then apply an alternate course of action to insure the safe outcome of a flight.  The prospect of a mid-air collision, on the other hand, bothers most pilots since it is a scenario that is real, but seemingly unpredictable and one that we may not be able to control.  We worry that we could be broad-sided out of the sky even while exercising all due caution and vigilance.  Indeed, there are few pilots out there who have not at one time or another had to take an evasive maneuver to avoid another aircraft in close proximity.
Mid-air collisions are seldom a single random event which involve two aircraft that simply run into each other.  Like other accidents, midair collisions have a causal chain.  That is to say that independent circumstances set the stage for the accident that is yet to come.  I have investigated a number of aircraft mid-air collisions over the years and in each situation there are identifiable links in the chain which allowed the accident to take place.  Let’s take a look at a few examples in the briefest of terms.  We are not focusing on the accident, but the contributing factors.  Most of these accidents happened over 15 years ago and all involved fatalities.
A Piper climbing out of Long Beach collides with a DC-9 on approach to Los Angeles international.  Factors: The pilot of the Warrior was relatively new to the area.  For unknown reasons his transponder was found to be in the “standby” position.  He was not in communication with ATC and he had entered Class B airspace without clearance when he hit the DC-9.
A Piper in-bound to the Oakland airport was on a 45 degree entry to runway 27 right and collided with a Cessna which had just taken off from runway 33 on a straight out departure.  Factors: The airport tower radar was out of service.  The tower failed to provide adequate warnings to each aircraft.  The use of runway 33 for takeoff and 27 for landing increased the collision conflict risk.
A Mooney had just pulled on to runway 12 at the Half Moon Bay airport and was on the take-off roll when it collided with a Cessna just about to touch down on runway 12.  Factors: Uncontrolled airport.  The Mooney did not communicate his departure on the unicom.  It was also determined that the pilot of the Mooney did not have a current medical certificate or biennial flight review.
A Cessna 172 and a Cessna 152 collided near Morgan Hill, California.  Factors: Each aircraft was on an instrument training flight with a student under the hood and an instructor in the right seat.  Both aircraft were operating without the benefit of ATC radar advisories in a corridor of busy airspace.
Each of the above respective “Factors” relate a measure of increased risk that were a fundamental part of the collision.  Playing armchair quarterback for a moment, put yourself in the position of each pilot.  What could have you done on each of these flights to minimize the risk, break-up the causal chain and prevent a tragic outcome? Some are obvious, some are not, but the point is that these accidents did not happen out of the blue and were preventable tragedies.
In the above accidents the weather was excellent VFR, the collisions took place below 5000 feet AGL and they occurred within 5 miles of an airport.  These underlying conditions often prevail during mid-air collisions.  There is no mystery here.  The airspace below 5000′ and in the vicinity of an airport brings together the greatest confluence of transitioning aircraft and the collision risk simply increases through statistical probability due to higher numbers of potential targets.  Pilots are also at much higher workload levels down low than in cruise flight and may not be giving the requisite attention to scanning for traffic.
Good VFR conditions tend to increase the volume of flight activity and can also bring a measure of pilot complacency given the relatively relaxed structure of the VFR operating environment.  The wild card contributing to the threat are pilots who disregard the rules, use non-standard pattern entry or departure procedures and don’t communicate their position or intentions especially at uncontrolled fields..  Even controllers can make mistakes so never hesitate to question them if you have any doubt or uncertainty regarding their communications.
Even if one pilot is mostly to blame by setting the stage for a collision, it will be of little comfort to the other pilot given the often fatal outcome.  Consider that there is always someone out there who is constructing their own causal chain towards a mid-air collision.  Basically they are an accident waiting for a place to happen, but it takes two to create the big bang.  By anticipating this threat and by actively using the collision avoidance skills that you were taught early on you need not be a part of their future.
Editor’s Note: This article was written by Ken Steiner prior to his retirement from the United States Aircraft Insurance Group as a Vice-President and Claims Manager. During his career, Ken investigated thousands of aircraft accidents involving small planes, crop dusters, helicopters, corporate aircraft, and airliners. He has been on-site at over 100 fatal aircraft accident investigations. He is currently an Aviation Investigative Consultant and is also a Pilot and Tactical Flight Officer for the San Mateo County Sheriff’s Air Support Unit. He owns a Cessna 182 based at San Carlos and holds ATP and CFI certificates with over 5000 flying hours.
