Accident Probe: Preflight, Interrupted

The airline industry long ago figured out that one of the most dangerous things in aviation is two pilots trying to fly the same airplane at the same time. One inevitable result of such an arrangement is that there are times when no one is flying, and one of the ways we know this is from the accident record. Airlines evolved the pilot-flying/pilot-not-flying concept to acknowledge this characteristic of crewed cockpits and established clear responsibilities for each pilot.

In single-pilot general aviation cockpits, however, we rarely have the discipline to carve out specific roles or tasks for a pilot-rated passenger, who probably is eager to help and/or demonstrate his/ her skills to the pilot in command. This often means delegating tasks like untying the airplane or looking up a CTAF and getting the destination’s automated weather. When there’s a clear delineation of responsibilities, the pilot-rated passenger can be a huge asset to ensuring the flight’s safety and efficiency.

It’s still up to the PIC to ensure the flight’s safe outcome, though, and this often means double-checking anything the pilot-passenger does. It also means checking for things that didn’t get done.

On September 24, 2017, at about 1829 Central time, a Beech C35 Bonanza collided with terrain during an uncontrolled descent after takeoff from the Harrell Field Airport in Camden, Ark. The commercial pilot and the pilot-rated passenger were fatally injured; the airplane was destroyed. Daytime visual conditions prevailed.

The pilot/owner and the pilot-rated passenger had just added 27.35 gallons of fuel to the airplane and were taking off for the final flight of the day, back to the airplane’s base. One witness questioned why the airplane was not gaining altitude after takeoff. Another witness saw the airplane flying just above the treetops, begin a left turn, and then descend and crash. Security camera video from about a mile away recorded the airplane in a steep, left-turning dive just before it impacted the ground and caught fire. No evidence of an inflight fire was observed in the video.

The airplane came to rest upright in a field on airport property about 172 feet east and 1000 feet south of the takeoff runway’s departure end. With one exception, all airplane components were contained in an area 33 feet long and 35 feet wide. The grass and bushes immediately surrounding the wreckage were burned.

Much of the wreckage was consumed by the post-crash fire. Examination revealed the landing gear was down and the flaps were fully retracted at ground impact. One propeller blade remained attached to the hub and was bent aft about 60 degrees beginning about eight inches outboard from the hub. The blade showed no signs of S-bending or chordwise scratches. The other propeller blade was broken at the hub mounting clamps and was bent aft about 10 degrees beginning about 12 inches from the hub. The blade showed chordwise scratches and leading-edge rubbing from midspan to the blade tip.

Flight control continuity was confirmed from the forward cabin area to all control surfaces. Many of the engine accessories were too fire-damaged to verify their pre-crash condition. Borescope examination of the engine cylinders revealed an exhaust valve was worn but functional. All spark plugs showed normal operational signatures. The primary fuel selector was disassembled and found to be in the right main fuel tank feed position. According to the POH, the fuel selector should be on the left main fuel tank for takeoff. For landing, the selector should be on the tank with the greatest amount of fuel.

At 1815, the departure airport’s automated weather observation station recorded calm winds and 10 miles of visibility in clear skies. Data recovered from a handheld GPS device showed the airplane reaching its maximum GPS altitude of 298 feet (about 170 feet AGL) at 1828:52. According to the NTSB, “a relatively flat, open, grass-covered area extended for about 2323 ft in the takeoff direction from the accident site to the airport perimeter.”

That exception to all of the airplane’s components being at the accident site? The airplane’s left main fuel tank cap was found about 4500 feet south of the rest of the wreckage, on the left side of the runway at the 1000-foot marker. The locking lever was engaged, and the cap showed no fire or impact damage.

The NTSB determined the probable cause(s) of this accident included: “The pilot’s improper decision to return to the runway instead of landing straight ahead when the engine lost power and his failure to maintain adequate airspeed while maneuvering for an emergency landing, which resulted in an exceedance of the airplane’s critical angle of attack and an aerodynamic stall. Contributing to the accident was the pilot’s failure to properly secure the left main fuel tank cap after refueling, which resulted in a loss of engine power due to fuel starvation during the takeoff climb.”

The NTSB added: “It is likely that the left main fuel tank cap was not secured after the airplane was refueled and fell off the airplane’s left wing onto the runway during the takeoff. Without the cap in place, fuel escaped from the left main fuel tank and subsequently starved the engine of fuel during the climb, resulting in the power loss. The pilot likely switched the fuel selector to the right main fuel tank in an attempt to restart the engine. When the pilot tried to turn back to the airport, he failed to maintain a safe airspeed, and the airplane exceeded its critical angle of attack and entered an aerodynamic stall.”

The NTSB’s scenario is a likely one, and we can imagine reacting in similar way to the situation. At that altitude, however, the apparent attempt to turn back to the airport simply wasn’t going to work—it would have been better to land straight ahead. And we’re rather impressed at the speed with which a fuel tank can be emptied when its cap is missing.

Although we’ll never know how and why the left main fuel cap wasn’t properly secured after refueling, it could have involved miscommunication between the two pilots or the pilot-rated passenger’s unfamiliarity with the cap itself. But it likely came down to an interruption in the pilot’s routine, and a failure to verify everything was secured after the refueling.

According to the Flight Safety Foundation (FSF), “Interruptions and distractions often result in omitting an action and/ or deviating from standard operating procedures (SOPs).” A task force assembled by the FSF to examine the impact of interruptions and distractions in the cockpit found that their primary impact was to “break the flow pattern of ongoing...activities (actions or communications)” including SOPs, normal checklists, communications and problem-solving activities. The FSF says to reestablish situational awareness, we must:

OEM Engine: Continental E-185-11

Empty Weight: 1650 lbs.

Maximum Gross Takeoff Weight: 2700 lbs.

Typical Cruise Speed: 148 KTAS

Standard Fuel Capacity: 39 gal.

Service Ceiling: 18,000 feet

Range: 510 NM

V_SO: 48 KIAS

This article originally appeared in the September 2019 issue of Aviation Safety magazine.

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