Carbohydrate ice causes serious accident for pilot on currency control flight : : FLYER

Carbohydrate ice cream doesn’t just happen in winter – it can happen almost any time. This is likely the cause of a serious accident involving two Piper PA-28 pilots in April, according to an AAIB report released last week.

The accident happened 1.5 miles from Prestwick Airport in April this year. It was a currency check flight for the holder of a Light Aircraft Pilot’s License (LAPL) with the club’s chief flight instructor.

The AAIB report said: “On the day of the accident the weather in Prestwick was generally good. The airfield weather report at 3:50 p.m. showed the following conditions: wind 250° at 10 kt, visibility greater than 10 km, cloud base 3,000 ft above sea level, QHN 1024 hPa, temperature 11 °C and dew point 5 °C.

“The temperature and dew point combination presented in a CAA carburetor icing risk chart from CAA’s Safety Sense Leaflet (SSL) 14 – Piston Engine Icing indicates that daytime conditions would have created a serious risk of carburetor icing at any power output.”

“While the aircraft was on the right base route for an approach to Runway 30 at Prestwick Airport, ATC lost visual and radio contact. The aircraft had suffered a loss of power and initiated a glide descent.

“During the final phase of the emergency landing, the aircraft crashed into a tree and then hit the ground vertically, nose down. Both occupants suffered serious injuries.”

The accident was further complicated by the fact that the CFI did not have a current medical certificate from the CAA and therefore could only be on board the aircraft as a passenger.

When the accident happened

The plan was to fly for about an hour, conduct some general handling drills south of the airport, including practicing stalls and emergency landings, and then return for three laps. Both pilots recalled using carburetor heat during these exercises.

After landing at Prestwick, the PA-28 took off again and entered a rightward course.

On the downwind leg, ATC asked the aircraft to enter orbit to make room [an Airbus] A320 is scheduled to approach runway 30; This is standard practice at Prestwick.

After three orbits, the aircraft was cleared by ATC to the right base and instructed to report “Final.” The call was acknowledged by the pilot and there was no sign of tension in his voice.

During the RTF exchange, the ATC controller observed the aircraft as it rolled out of its final orbit toward a right base orbit. After the exchange, the air traffic controller turned and looked at the A320 in the left circle while transmitting a message to that aircraft. When they turned back, the air traffic controller could no longer see G-BVNS.

Toward the end of the final orbit, the PIC had allowed the aircraft to descend to an altitude of approximately 800 feet msl. As the aircraft taxied to a base track, both occupants remembered that the engine had failed.

The CFI, assuming that the pilot-in-command was unaware of the engine problem, shouted “I’m in control” and took control. He set the aircraft up to glide and, looking ahead, could see Runway 21 and the SAR hangar near the threshold of the disused Runway 25 at Prestwick. His first thought was to attempt a glide to that runway.

However, in his own words, he soon realized that the airfield was “moving up the windshield” and was out of glide range.

After taking control, he instructed the PIC to change the fuel tank selection, which it did. Although the CFI was on the right side of the aircraft, he felt that there were no suitable landing options on the right side, but rather “saw a patch of open ground on the left side.” The CFI considered an emergency call but decided to focus on the emergency landing.

In the final stages, he initiated a left turn to align with the longest axis of the landing strip, but saw trees that he believed would impede the aircraft’s final approach. He described lifting his nose to clear the trees. The aircraft reduced speed and although he did not recall hearing the stall warning, he described the aircraft as being in a slight buffet.

The aircraft struck the top of a tree in a left turn, stopping the aircraft’s forward speed and causing it to roll to the left, yaw and pitch downward. The plane hit the ground vertically, nose down.

The PIC recalled that he had performed the checks upwind, assuming that he had used carburetor heat, and that he had performed the orbits upwind. As he prepared to descend to the airfield, he remembered that the engine speed gauge had dropped to about 500. He remembered the CFI saying something but couldn’t remember what was said.

He saw trees in front of him and a green area behind them. He recalled that the CFI applied throttle but the engine did not recover. His last memory of the flight was that the nose was raised while the aircraft was in a “right-side” attitude. Then the plane was on the ground. He believed he had flown the plane.

Diploma

The engine stalled, most likely due to carburetor icing, and an emergency landing occurred. The aircraft crashed into trees during the final phase of the approach to the emergency landing and lost control. Both occupants survived, but suffered serious injuries.

Download and read the full report here

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