Even in comparable aircraft, charter flights under Part 135 suffer far fewer accidents than flights made under Part 91. In piston-engine airplanes, for example, the Part 135 accident rate is 45-percent lower, and the fatal accident rate is nearly 60-percent less. Several factors figure into this, including more stringent requirements governing aircraft equipment (such as dual alternators and dual vacuum pumps for IFR flights) and pilot qualifications. But differences in operating rules come into play as well, limiting the decisions left to pilot discretion and with them the opportunities to get into mischief. Regulations governing instrument flights require adherence to published takeoff minimums and prohibit pilots from even attempting an approach when ceilings or visibility are below the minimums defined for that procedure.
Of course, regulations do more to improve safety when they’re actually followed.
On the morning of March 30, 2011, an airline transport pilot flew a Cessna 310 from Portland, Ind., to the Dayton-Wright Brothers Airport in Ohio to pick up a client for a Part 135 passenger flight. His medical application, filed a little more than two months earlier, claimed nearly 20,000 hours of flight experience; company records suggested that more than 15,000 of them had been logged in Cessna 310s. The pilot and his passenger departed Dayton a little before noon en route to the Pike County Airport near Pikeville, Ky., where the passenger had a business appointment. He intended to return to Dayton after the meeting.
The NTSB described the Pikeville Airport, elevation 1,473 feet, as “located in mountainous terrain … and built atop a ridgeline in a reclaimed surface mine area.” The ridges surrounding it don’t align in any predictable pattern. Its main runway is 9/27. Both directions are served by nonprecision GPS approaches, and Runway 27 also has an ILS. Decision height for the ILS is 1,666 feet msl (200 feet above ground level); the minimum descent altitudes for the GPS approaches are 1,960 feet (506 feet agl) for Runway 9 and 2,120 feet for Runway 27.
The flight from Dayton was apparently uneventful. As the Cessna flew southeast toward Pikesville, the pilot requested and received clearance for the GPS approach to Runway 9. He also contacted Pikesville Unicom, reporting that he was 20 miles out and requesting the current weather. An airport employee told him that winds were calm, and said that while the AWOS showed ceilings of 200 to 300 feet and visibility of one to one and a half miles, actual conditions on the field were worse.
Radar track data showed that the Cessna intercepted the final approach course at the required initial altitude of 4,500 msl and began a gradual descent. It crossed the final approach fix at 3,700, 500 feet above the minimum step-down altitude, began to descend more quickly, and then leveled off at 2,000 feet msl. After about 30 seconds it began descending again; the last radar contact came about half a mile from the threshold, in line with the runway, at an altitude of 1,700 feet.
Near the approach end of Runway 9, two workers on a job site below the top of a ridge heard the sound of an approaching airplane. The day was foggy, and the bases of the clouds were barely above the treetops along the crest. The twin Cessna emerged from the clouds, flying directly above and along the ridgeline until it grazed the tops of several trees. Apparently in response to that contact it began to pitch up; one man said he “thought it was going to make it over.” Instead, the airplane collided with a larger tree and disappeared from sight.
The wreckage was found nearly half a mile southeast of the threshold and 650 feet below the airport elevation. The pilot and his passenger had both been killed, and “[t]he nose compartment, cockpit, and cabin areas were consumed by post-crash fire. Both engines and propeller systems displayed significant impact and fire damage.” However, the condition of the wreckage indicated that both engines were producing power at the moment of impact, and the witnesses agreed that the sound of the engines was smooth and continuous until then.
The NTSB found the probable cause of the accident to be “the pilot's flight below the published minimum descent altitude in instrument meteorological conditions,” and it’s hard to argue with that as far as it goes. But it’s also worth wondering why he had requested that approach in the first place. Conditions were clearly below minimums, and in calm winds, Runway 9 offered no obvious advantages beyond an initial fix that was a little closer to their current position.
The operator’s chief pilot told investigators that a premature descent below MDA was “out of character” for his colleague, adding, “The only thing I can think of is that he was running a little late.” Perhaps a problem for a passenger with an appointment to keep became a problem for the pilot who’d promised to get him there. The ILS approach course is 13 miles long and requires radar vectors to final. It might have added another 30 miles, perhaps 12 to 15 minutes of flight time. It probably would have been worth it. As low as the weather was, they might still have missed the approach, but their chances would have been better. Under FAR 135.225(a), they had no other choice.