Aftermath: Expectations Pave The Way To Accidents

Pilots allow a false reality at night and in IMC to lead them astray

airplane cockpit at night
The mental picture that we form of our surroundings when we cannot see them is an essential element in night and instrument flying.Rodrigo Soares/Unsplash

The hill was not particularly steep nor particularly tall nor particularly close to the runway—so nondescript, in fact, that pilots probably barely took note of it. In daylight they would maintain the runway heading while climbing and the hill would sink harmlessly below and behind them.

At night it could be a different matter. That the hill was a potential hazard had been recognized, and a row of red lights on 30-foot stanchions had been erected, some distance from the side of the runway and parallel to it, to remind pilots not to drift to the left. The instrument departure procedure instructed pilots to “climb visually over airport, to cross airport at or above 1,500 feet, then proceed on course.” The phrase “cross airport” was unclear; it was later changed to a more conventionally worded instruction to maintain runway heading.

On a moonless night two instrument-rated pilots took off in an Aerospatiale Trinidad with a passenger in the back seat. Both had flown out of the airport before—between them, 18 times—but not at night. They were on an instrument flight plan, but the night was clear and, because both pilots were familiar with the airport, it is possible that neither of them had read all the fine print on the departure procedure. The pilot flying began a left turn shortly after takeoff. The tower controller asked the pilot whether he had the hill in sight; the pilot replied, “Say again?” The controller repeated the question. As he released the mic key, he saw the trees on the crest of hill illuminated by the Trinidad’s landing light.

Both pilots died when the airplane struck the trees; the passenger survived. He said from his hospital bed that he had not been aware of anything untoward until he heard the controller’s call; then he looked out the window and saw the trees.

Many unfortunate events have demonstrated that two pilots are not necessarily better than one. The pilot in the right seat, in this case, was an instructor, and you might have supposed that professional habit would have caused him to monitor the actions of the pilot flying.

Either he did not, or both pilots were equally oblivious of the hill despite having seen it many times in daylight. Most likely the problem was just that the hill was not that impressive. In daylight it did not seem threatening in the least, and so, in the pilot’s rough mental map of the airport, the surrounding terrain was more or less flat.

The mental picture that we form of our surroundings when we cannot see them is an essential element in night and instrument flying. At times, however, even a small difference between what we believe to be the case and what actually is the case might be fatal. This was such a time.

A mental picture of weather might prove dangerously inaccurate too.

Read More: Aftermath

The instrument-rated commercial pilot of a Piper Lance, with a single passenger aboard, missed his first attempt at an NDB approach at a rural airport. Another pilot, whom he knew, had just made the approach successfully, landing straight in on Runway 16. He reported that the ceiling was ragged, 700 to 800 feet, with a mile visibility in fog. The Lance pilot, nearly a quarter of whose 600 hours had been flown in actual instrument conditions, came around for a second attempt.

It was dark. The pilot on the ground heard the Lance pass overhead northbound on the outbound leg of the approach; several minutes later he heard the Lance again, this time southbound, but did not see its lights. About 20 minutes after the last transmission from the Lance, he drove around the airport looking for it. By then, visibility had deteriorated to 1/4 mile in fog.

An hour later, a pilot taking off from Runway 16 reported hearing an ELT near the departure end of the runway. Searchers found the wreckage of the Lance 750 feet south of the threshold of Runway 34. From the curved ground scar and the fact that the left wing had struck the ground first, possibly in a steep bank, National Transportation Safety Board investigators concluded that the pilot had tried to circle to land on 34 and had snagged a wing on the turn from base to final.

It’s axiomatic that if an airplane does not descend below the minimum descent altitude for any approach, it will not hit the ground. The circling approach, however, challenges even that truth, because conditions can change while the circling is taking place.

The wind, 250 at 6, was not a factor in the choice of a runway, but it might have been a factor in the movement of the fog. Most likely, denser fog had drifted in from the west, and that was the side of the runway on which the Lance pilot flew his downwind leg.

It was the natural side to choose for a standard left-hand pattern, and it put the runway lights on the pilot’s side. But if the visibility was dropping on the west side of the airport, it might have had the unintended effect of encouraging the pilot to drop to a lower altitude to keep the lights in sight.

The pilot began his first approach expecting, on the strength of the preceding pilot’s report, to break out of a reasonably high ceiling with a view of the runway. Evidently he didn’t. Either he didn’t get down to the MDA in time or the ceiling was now lower than it had been a few minutes earlier.

He must have caught sight of the runway lights on the second approach, but too late to land straight in on Runway 16. Once he saw the lights, he must have sidestepped to the downwind. This maneuver apparently succeeded, because the wreckage was on a correctly positioned base leg. It’s likely that the pilot had the lights in sight during all or most of the downwind leg, because he knew when to turn base. It must have been only at the last stage of the approach that the pilot lost awareness of his altitude.

Discussions of the hazards of night flying often focus upon illusions of height that might occur during a straight-in approach over unlighted terrain. Pilots with no visual references other than the runway lights sometimes get too low; apparently we do not have a firm idea of what a runway should look like when it is reduced to two converging rows of lights. The problem of estimating height from oblique, intermittent or obstructed views of the runway is less well-defined, but it’s not hard to imagine that lights glimpsed obscurely or fitfully through fog, and viewed from a low angle, probably give little reliable information about the airplane’s height.

This was a case in which expectation lured a pilot on until reality clashed with it. In principle, the pilot may not descend below the MDA on a circling approach until landing is assured; but that rule leaves the pilot lots of wiggle room. The circling approach can be a trap. In conditions of uncertain visibility, most especially at night, it should perhaps not be attempted at all.