FAA Supervisory Operations Inspector Jack Patrick and I were climbing out of San Diego's Montgomery Field in a Piper PA-28-201 on a flight to Imperial, California. I was flying from the left seat, and he was giving me an FAA annual proficiency check. It was a typical late-summer morning, sunny but hazy. Visibility was about 10 miles. We were climbing on an easterly heading when Air Traffic Control (ATC) advised us that there was a twin-engine Aero Commander at our 12 o'clock and three miles, descending toward us. Straining our eyes to see through the haze, I told the controller that we were looking but didn't have the traffic in sight. We were instructed to discontinue our climb and advise when we sighted the target. A short time later, Jack and I saw the airplane at the same time. We advised ATC, and were told to resume our climb. I reestablished the climb and was keeping the traffic in sight when, suddenly, an Aero Commander appeared in our top left windshield, no more than 100 feet away and headed straight toward us. Instinctively, I pushed the nose down and banked to the right as the Aero Commander disappeared under our left wing.
Jack and I looked at each other with startled expressions as I said, "How could that have happened?"
Why did it happen — and what was that mysterious airplane we had been looking at since advising ATC that we had our traffic in sight? You probably wouldn't believe it if I told you. So I'll tell you first about a catastrophic midair collision involving a similar mystery airplane.
This accident occurred at 9:01:47 a.m. on September 25, 1978, about three miles northeast of Lindbergh Field in San Diego. I was the manager of the FAA's San Diego General Aviation District Office at the time.
Just moments before the midair collision with a Cessna 172, the first officer of Pacific Southwest Airlines Flight 182 said, "There's one underneath; I was looking at that inbound there." Later, the accident report concluded, "There was not a third aircraft in the vicinity of the Cessna that could have been mistaken for it by the flight crew of Flight 182."
What was this "mystery" airplane the first officer reported seeing shortly before the collision?
Flight 182 was a Boeing 727 on a visual approach to Lindbergh Field, and the Cessna was on a local instrument-training flight, climbing on about the same heading.
At 9:00:15, Approach Control advised, "PSA 182, traffic's at 12 o'clock, three miles." The first officer, who was flying, said, "Got 'em," and the captain reported, "Traffic in sight."
They were instructed to maintain visual separation and contact Lindbergh Tower. They contacted the tower on the downwind leg and were advised, "PSA 182, traffic 12 o'clock, one mile, a Cessna." They did not have the Cessna in sight at this time and thought that they had passed it, so they continued the approach.
The airliner collided with the Cessna near 2,600 feet and fell to the ground in a residential area. A total of 144 people were killed. The weather was clear, and the visibility was 10 miles.
The National Transportation Safety Board (NTSB) determined that the probable cause of the accident was the failure of the flight crew of Flight 182 to comply with the provisions of a maintain-visual-separation clearance, in-cluding the requirement to inform the controller when they no longer had the other aircraft in sight.
Early in the investigation there was a question of whether the flight crew had actually seen the Cessna — or if it had seen another aircraft in the vicinity — when the captain reported, "Traffic in sight." There was rumor of a "mystery" airplane in the area, which the flight crew thought was the target aircraft. Many witnesses said they saw another aircraft, but they all differed on the type of aircraft, the direction in which it was flying, and its proximity to the collision site.
After analyzing witness statements, numerous runs of radar data, ATC tapes, and all other evidence, the NTSB summed up the mysterious-third-aircraft theory with the following conclusion:
"In order for any third aircraft to have been mistaken for Cessna N7711G, it would be necessary to conclude that the aircraft was flying in the vicinity of the Lindbergh Field traffic pattern at the same time Cessna N7711G was sighted by Flight 182's flight crew; that it was not equipped with a transponder; that its pilot did not comply with the federal regulations governing flight in the area; and, that…based on the flight crew's identification of the aircraft type…it was a Cessna or an aircraft closely resembling a Cessna.
"While it is possible that all this might have occurred, the weight of the evidence indicated that there was not a third aircraft in the vicinity of the Cessna that could have been mistaken for it by the flight crew of Flight 182."
Those conclusions were not entirely accurate, because there was a third aircraft flying in the vicinity of the Lindbergh Field traffic pattern at the time Flight 182's flight crew said it had the "traffic in sight." (They never positively identified the target as a Cessna.) This third aircraft had a transponder, and its pilot was in full compliance with the federal regulations; however, it was not a Cessna or an aircraft closely resembling a Cessna. It was another PSA Boeing 727 on final approach to Lindbergh Field.
During the investigation, there was a lively discussion between the NTSB and FAA investigators about the possibility of the flight crew's mistakenly identifying the other 727 as the Cessna, and not actually seeing the Cessna until those moments just prior to impact. The first officer seemed to be telling us just that when he stated, "There's one underneath; I was looking at that inbound there."
One FAA inspector was so adamant about the other 727's being the probable cause of the accident that the chief NTSB investigator asked me to remove him from the investigation team. Though I tended to agree with the inspector's conjecture, I could not condone his obstinate behavior. Besides, it was too early in the investigation to jump to such a conclusion.
Later, in determining the probable cause, the NTSB apparently decided to disregard the other 727 as a factor in the accident, because it was on the runway and not in the immediate vicinity at the time of the collision.
The radar ground tracks plot of the aircraft in the vicinity (see illustration, p. 124) clearly shows the other 727 on approach at Flight 182's 12 o'clock position, about six miles away at 9:00:20, when the air traffic controller reported the Cessna at the flight's 12 o'clock position and three miles away. Although the 727 was twice as far away as the Cessna, which would make its details less recognizable, it would actually have been more visible than the Cessna because it was nearer the horizon. The Cessna was below the horizon and would have been very difficult to see because of the background clutter of houses and trees. Under the existing conditions, at a distance of six miles, the flight crew probably could not tell what type of aircraft the 727 was, but since they were looking for a Cessna, they assumed it was a Cessna. The other 727 was on a very short final when Flight 182's crew was advised that their traffic was at 12 o'clock, one mile, and they couldn't find it. That would explain why the first officer still referred to it as "that inbound there" just before the collision, even though the airplane was on the runway by that time. It is interesting to note that the Air Line Pilots Association's accident investigation department independently confirmed the feasibility of this interpretation of the accident. The association twice filed petitions asking the NTSB to reconsider its findings, but to no avail. Although I was unaware of the contents of the ALPA petitions at the time, their content closely parallel the concerns I have expressed here.
All of this was mere speculation until about a year later on August 31, 1979, when Jack Patrick and I were involved in the near-midair collision with the Aero Commander. This convinced me beyond any doubt that the PSA flight crew could have easily mistaken the second PSA 727 for the Cessna 172 and erroneously reported they had their traffic in sight.
After barely avoiding the Aero Commander, Jack and I had to search for our mystery airplane for a few seconds — but there it was, still four or five miles ahead. It was a McDonnell Douglas DC-10 heading for the Lindbergh Field approach.
How could that have happened? Easy. We were looking for an Aero Commander at three miles; when we saw the DC-10 at eight or nine miles, we mistook it for the Aero Commander.
The lesson I learned from these "mystery" airplanes is twofold: Don't be in any hurry to relieve ATC of its responsibility to provide aircraft separation, and keep looking until the reported traffic can be positively identified by aircraft type before stating assuredly, "Traffic in sight."
John R. Hull is a freelance writer in San Diego. For 30 years, he served the FAA as a flight standards inspector and instructor; Hull managed the San Diego Flight Standard's District Office for 13 years.
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