Classic Aftermath: The Unseen

Remarkably—since one tends to think of midair collisions as unsurvivable accidents, with both airplanes spinning out of the sky in pieces—the Searey fared much better. The 172’s propeller had taken a chunk out of the Searey’s right wing and partially severed its aft fuselage a few inches ahead of the empennage. The 4,500-hour pilot, 59, heard a loud sound but had no idea of its cause. Perceiving that he had lost pitch control from the stick—probably because the elevator, even if its cables were not severed, was just making the entire empennage flop up and down—he guessed that something in his recently built airplane might have broken. The Searey configuration is similar to that of the Icon A5 (and, anciently, the Republic Seabee), with the pusher engine sitting atop the high wing and behind the cabin. Finding that he could use power from the high-mounted engine to keep his nose down, he was able, with admirable airmanship, to make a controlled crash landing. Neither he nor his passenger, a 9-year-old girl, was injured.

Almost exactly two years later, and at a place not many miles distant, another midair collision took place. This one involved a Cessna 120 and a Piper Cherokee 140, and was similar to the other in that the Cherokee overtook the Cessna and its propeller sliced off the 120’s empennage. The 120’s left landing gear, in turn, severed the left wing of the Cherokee. The Cherokee’s pilot and his passenger died, as did the other pilot, who was alone in the 120. In both accidents, the overtaking airplane closed slowly on the one ahead, and therefore its pilot could have had the traffic in sight for some time before the collision occurred.

Neither encounter was random: In both instances, the airplanes were part of a planned activity. In the case of the 172 and the Searey, the pilots were taking part in an EAA Young Eagles event in which local pilots give rides to young people to introduce them to general aviation. The pilots had been briefed to depart straight out and fly for 10 miles along the north side of an elongated rectangle bordered by two roads 2 miles apart. They were then to turn to the right and return to the airport along the south side of the rectangle before entering the traffic pattern at midfield on a crosswind leg. The route was to be flown at 1,800 feet, except that airplanes were to be at 1,560 feet (field elevation is 752 msl) on the crosswind leg. The collision occurred at a height of 1,625 feet, just as the Searey pilot was preparing to make the right turn to crosswind. The Searey had climbed slightly, and the Cessna had descended. The Cessna’s groundspeed was 90 knots, and the Searey’s 70.

Pilots had been instructed to make position reports at several landmarks along the course, and the Searey pilot said that he had done so. The 172 pilot ought, then, to have known there was an airplane somewhere not far ahead of him. A computer simulation conducted by the National Transportation Safety Board (NTSB) showed that the Searey would have been visible at the bottom of the Cessna’s windshield for some time before the collision. The NTSB noted, however, that the Searey, seen from directly behind and presenting its smallest cross section, would have been “a small dot in the terrain” until seconds before impact and, furthermore, “would have presented little relative motion to the other pilot, making detection more difficult.” All airplanes are small dots until they are about to hit you, however, and with a closing speed of only 20 knots, the brightly colored Searey must have been more than a “small dot” for some time before the Cessna hit it. Dot or not, the NTSB concluded the cause of the accident was the Cessna pilot’s “inadequate visual lookout for known traffic.”

The collision between the Cherokee 140 and the Cessna 120, two years later, also took place in the context of an organized event, though one less structured than the EAA’s Young Eagles activity. Weather permitting, a group of friends habitually flew, in as many as seven airplanes, from their home field of Hamburg, New York (4G2) to St. Marys (KOYM) in Pennsylvania for Sunday breakfast. The distance is about 80 nm. On the cloudless day of the accident, six airplanes were making the trip. Since the 85 hp 120 was the slowest of the group, it departed first; the Cherokee took off 78 seconds later. Their flight paths converged four minutes later, 6 miles south of the airport.

According to one member of the group, the 120 pilot was usually the first to arrive at 4G2 and the first to take off; after that, however, airplanes departed at random, whenever they were ready. Unless it was turbulent, they cruised at 3,500 feet and communicated with one another on the unofficial air-to-air frequency of 123.45. They never attempted to fly in close formation.

Such informal arrangements are typical when groups of pilots fly anywhere together. The logic of having the slowest airplane take off first is obvious; otherwise, all the others would have to cool their heels waiting for him at the destination. The trip was short, but the difference in block time between a 90-knot airplane like the 120 and, say, a 175-knot Bonanza would still be half an hour. It would certainly make less sense for the Bonanza to depart first and the 120 last.

On the other hand, the scheme created a near certainty that faster airplanes would overtake slower ones. Because they had agreed to fly at the same altitude, and all would be flying the same course on the same heading, the same problem would arise as was described in connection with the Skyhawk and the Searey: The airplane ahead would be a small, almost stationary, hard-to-see dot until the overtaking airplane was quite close to it.

A member of the group who discussed the accident with the NTSB said that henceforth they would have the fastest airplane depart first; the group had also discussed equipping its airplanes with ADS-B traffic depiction. Even though this accident was nearly identical to the other, this time the NTSB did not invoke the formula of “inadequate visual lookout.” Instead, it blamed the accident, somewhat tautologically, on “the failure of the second airplane’s pilot to see and avoid the first airplane. ...”

Failure to see is not quite the same as failure to look, but it is hard to imagine, when two airplanes approach each other so gradually, that they are not related.

*This article is based on the NTSB's report of these accidents and is intended to bring the issues raised to our ­readers’ attention. It is not intended to judge nor to reach any definitive conclusions about the ability or capacity of any person, living or dead, or any aircraft or accessory. *