A Game of Inches

A flight into terrain misses being merely a close call by the barest of margins


A look at accident statistics can be a bit haunting. The NTSB has determined that about 80 to 85 percent of general aviation accidents are caused by human error. While some kind of equipment failure or weather problem may contribute to the accident, the fact remains that bad judgment and lousy decisions are what usually lead to bent metal and broken lives.

Many times the pilots mistakes are induced by outside pressures. The desire to get home, make a meeting, meet a schedule, beat weather or impress someone can lead to shortcuts and risky maneuvers. Often the pilot gets away with it, which reinforces the possibility that it will happen again. Sometimes, however, the pilots luck runs out.

The pilot of a Piper Chieftain was repositioning the airplane from Santa Rosa, Calif., to Oakland Metropolitan International Airport, a distance of about 52 nm. The airplane was operated by a Part 135 charter company and the Chieftain and another plane were being repositioned for flights the next day.

The pilot held an ATP certificate and had recently passed an instrument proficiency check and a Part 135 check ride. She had 4,300 hours, including 63 multi-engine hours in the previous three months. Her last biennial review had been seven months earlier in the same model airplane as she was flying this March evening.

Before departing from Sonoma County Airport, the pilot noted the weather was marginal visual meteorological conditions. Visibility was four miles in light rain, with a broken layer at 2,900 feet and an overcast layer at 4,400 feet. Records show she did not obtain a weather briefing nor file a flight plan. The flight would take less than 30 minutes.

It was a familiar flight. The operator said the pilot had flown this route two to three times a week for the past two years. Standard company procedures allowed the pilots to make the trip using a combination of dead reckoning and pilotage.

The other company airplane took off first, with the Chieftain following about one minute later. The first plane followed the regular route, flying southeast along U.S. Hwy 101 before turning south over San Francisco Bay toward Oakland.

A Change of Plans
The Chieftain pilot, however, had another idea. She dialed in the Oakland Vortac on her VOR receiver and the middle marker for one of the ILS approaches on her ADF. Armed with a direct route, she set off for the quickest trip home she could manage.

Waiting in Oakland was a final exam for a class she was taking. She was to give a speech for her exam, and worried that her work schedule would cause her to be late. Her instructor sympathized, but said he could not hold class longer than its regularly scheduled dismissal time. If she made it before class was over, she could give her presentation. If not, she failed the exam.

The route the pilot took was five to 10 miles west of the normal route. Under the best of conditions, she could shave perhaps five minutes from the short flight. But with her pressure to get there, every minute counted. As she flew on, the weather conditions deteriorated, with the ceilings falling and the possibility developed that she would be shooting an instrument approach at Oakland.

At one point, the other pilot called her on the radio and asked about her progress. She said she was still back there. Later, as the lead plane descended toward Oakland, the pilot encountered lowering ceilings and had to go to 1,200 feet to stay VFR. He called the Chieftain pilot on the company frequency to advise her. His transmission was met with silence.

The pilots direct route took the Chieftain over a range of hills where a single peak rose to 1,600 feet msl. The Piper struck the hill at about 1,500 feet. The pilot was killed.

A review of the airplanes radar returns showed the Chieftain was cruising at 2,000 feet until about 30 seconds before impact. At that point, it began a 1,000 fpm descent that remained constant until impact.

The terrain was such that if the pilot had been a mile or so to the east the airplane would have cleared the terrain. And if the descent would have begun 10 seconds later, she would have been past the peak and could have descended safely on the other side.

The Three Whys
Three primary human factors elements came into play. It was a short flight, the weather was marginal VMC at the point of origin and it was a familiar route.

Its well known that most pilots do not prepare for short flights with the same level of care they employ on longer flights. Although the regulations are clear about gathering preflight information, the fact remains that short hops lead pilots to cut all kinds of corners while flight planning and preflighting.

If you could ask her, shed probably say she skipped a weather briefing because the weather at takeoff was above VFR minimums. After all, how different can the weather be only 50 miles away? While she may have gotten some weather information from the FBO computer or monitoring ATIS broadcasts en route, nothing she discovered was enough to make her think twice about scud running in the Chieftain at 200 knots.

Shed flown between the two airports 100 to 150 times in the past two years. She usually flew along the highway, and one would think that after that many trips she would know that small range of hills was there. Maybe she thought she was past it when she began her descent. At any rate, because the actual time the direct route would have saved was so small, it may be that her preflight preparation did not include looking at the ramifications of her route change in any organized way.

Even after accounting for those human factors issues, however, its still a mystery why the accident happened. If she had gone into IMC or couldnt see the ground for other reasons, why did she descend? Why not climb, confess and get an IFR clearance?

Unfortunately, some of the clues that may have helped unravel the mystery were destroyed by the impact and post-crash fire. Its unknown whether she had any charts out, much less whether they were sectionals or low-level enroute charts.

Following the route on a sectional chart requires you to flip the map over. The distraction may have played a part in the premature descent. Its also conceivable that she was momentarily heads down looking for a frequency to call to get an IFR clearance.

Having said that, its most likely that she began her descent to stay below the clouds and never saw the ground rising up to meet her flight path.

But there are other realities of flying that probably also played a factor.

Pop-up clearances are hard to get in many parts of the country. Compound that with the relatively short flight at hand and it probably didnt seem worth it to file IFR – especially if the routing would have led to a longer vectored approach and the time savings she was hoping for by flying direct would have evaporated.

The rising terrain and lowering ceilings put the squeeze on her. Given her qualifications and the airplane she was flying, the logical choice would have been to climb and fess up. Stopping her would have been a potential fear of enforcement action that could have derailed her aviation career, and her unquestioned desire to arrive at her destination as quickly as possible. Then theres the wildcard: Pilots are a notoriously independent lot. Many dont want to admit – even to themselves – when they need help.

The continued problem of VFR into IMC accidents seems to defy solution. Although some such crashes are by unqualified pilots or unequipped airplanes blundering along where they have no business being, this pilot and her airplane were easily capable of completing the flight safely.

Chalk it up to poor planning or lousy judgment on the part of the pilot, sure. But its also important to think about why this type of accident is so prevalent and why even veteran pilots can be goaded by outside pressures into making rookie mistakes.

Also With This Article
Click here to view “Too Low, Too Soon.”

-by Ken Ibold


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