Facts
The accident occurred on 24 August 2009 at 16:33 local time at Müllwis, community of Affeltrangen, Thurgau, Switzerland. The aircraft was a Piper PA-28-180 Cherokee, registration HB-OYN, owned and operated by Motorfluggruppe Thurgau. The pilot, a Swiss citizen born in 1986, held a JAR private pilot license first issued on 26 April 2008. He had approximately 60 total flight hours, with about 10 hours on type, and about 6 hours in the last 90 days.
The flight was a private VFR round trip planned from Lommis airfield (LSZT) with an estimated duration of one hour. The pilot had arranged with an acquaintance to take three passengers. The pilot inquired about passenger weights: the acquaintance stated 70 kg, and the other two passengers 80 kg and 85 kg respectively.
On the morning of the accident, the pilot checked takeoff distance tables from the owner's handbook and concluded the available grass runway at Lommis (615 m) was sufficient. He fueled the aircraft with 69 liters of AVGAS and performed the pre-flight check. After boarding, he started the engine and completed checklist items. Wind was near calm, runway 06 in use.
For takeoff, the pilot set flaps to 25° and taxied onto the grass runway, rolling further west to maximize takeoff distance. He held the brakes, applied full power, and the engine reached about 2200 RPM. The aircraft accelerated normally. About 22 seconds after starting the takeoff roll, at an indicated speed of about 60 kt, the pilot lifted off. Passengers made loud noises and calls.
Approximately eight seconds after liftoff, passengers noted a red light. Between 13 and 14 seconds after liftoff, a marked increase in pitch angle occurred, and about two seconds later, the right front passenger said "stall warning!". About 21 seconds after liftoff, engine RPM was 2300. About five seconds later, the aircraft reached its highest point and began to descend. Six seconds later (32 seconds after liftoff), the aircraft started rolling right, and the pilot transmitted "Mayday, mayday, mayday!". Four seconds later, control wheel was moved fully left. One second later, about 59 seconds after start of takeoff roll (37 seconds after liftoff), the aircraft struck a cornfield with high sink rate and low forward speed. The nose and main landing gear were torn off. The aircraft came to rest after a few meters.
The pilot ordered immediate evacuation. All occupants were conscious and exited through the cornfield, then lay under nearby trees. Police and two REGA rescue helicopters arrived about 15 minutes later. Shortly after evacuation, a fire developed under the engine forward left, burning the fuselage from the firewall to the rear cabin wall. Aircraft documents, flight manual, and pilot's records were destroyed.
The distance from start of takeoff roll to accident site was 1.38 km, 670 m from runway end. Corn height about 2.5 m. Impact occurred with slight right bank, right wing first, causing the nose to yaw right about 70°. Wings remained intact and undamaged by fire; both wing tanks contained AVGAS 100LL up to filler neck, about 130 L.
Injuries
The pilot sustained light injuries; one passenger suffered serious injuries, two passengers light injuries. No third-party injuries.
Weight and Balance
The pilot completed a "VFR Flight Notification" form with a weight and balance section. He listed a total load of 335 kg (165 kg front seats, 165 kg rear seats, 5 kg baggage). The form showed for HB-OYN a maximum permissible load with full main tanks of 345 kg. Calculated takeoff mass was 1050 kg; maximum takeoff mass per AFM was 1089 kg. The pilot did not complete the detailed loading calculation on the back.
Takeoff Technique
The owner's handbook states: "Allow the airplane to accelerate to 50 to 60 miles per hour, then ease back on the wheel enough to let the airplane fly itself off the ground. Premature rising of the nose, or raising it to an excessive angle will result in a delayed take-off. After take-off let the aircraft accelerate to the desired climb speed by lowering the nose slightly."
Cause
The accident was due to the aircraft descending after takeoff as a result of the chosen flight attitude. A loss of control near the ground followed and led to ground impact. The following factors probably contributed: high takeoff weight with high outside temperature, a tendency for a tailwind when leaving the ground layer, distraction of the pilot by passengers, and low flight experience of the pilot.