ERA21LA313

The pilot’s failure to abort the takeoff in sufficient time to stop the airplane on the runway remaining. Contributing to the accident was the lack of airplane takeoff performance due to the pilot’s failure to assure that the carburetor heat control was in the off position and the elevated density altitude.

The accident occurred while the flight was taking off during an aviation youth camp. The pilot reported the airplane became airborne and climbed in ground effect to an altitude of about 50 ft above ground level (agl). He stated the airplane climb rate seemed sluggish, so he transitioned the airspeed from the best rate of climb to the best angle of climb, but he still did not get the climb performance he expected. The pilot momentarily reduced the power to land, then realized there were trees and a fence off the end of the runway, so he added power to land on a lawn just beyond the airport. The pilot applied rudder during the landing roll to avoid trees and in doing so, the airplane nosed over and came to rest nose down, leaning up against a tree. During the impact sequence, the airplane was substantially damaged. The pilot and the two passengers received minor injuries. According to witnesses, during the takeoff the angle of climb was much less than expected and the airplane never climbed above 10 to 20 ft above the runway. One witness reported the engine sounded sluggish. Several of the witnesses reported seeing the airplane bank to the right before they lost sight of it. One stated the airplane pitched down and rolled to the right, then pitched up and rolled to the left before impact. Review of weight and balance information revealed that the airplane was within the weight and balance envelope during the flight. Examination of the wreckage did not reveal evidence of any preimpact failures or malfunctions that would have precluded normal operation. However, the carburetor heat control knob was found to not be fully closed and the carburetor heat door was found to be open. The airplane’s performance charts indicated that the airplane would need a 950-ft ground roll for takeoff and 1,680 ft to clear a 50-ft obstacle. The takeoff was being conducted from a runway that was 3,309 ft long. There were two takeoff abort points designated in the briefing for the event, one for each runway. The pilot confused the abort points and was using the abort point designated for the opposite direction runway. The abort point for he should have used was 830 ft from the beginning of the runway, while the abort point he actually used was 1,300 ft from the beginning of the runway. This confusion regarding abort points reduced the amount of available runway remaining for the pilot to stop the airplane once he realized the airplane was not going to clear the trees at the end of the runway. Based on the available evidence, a loss of engine performance likely occurred during the takeoff because the carburetor heat control knob was not fully closed. This loss of power would also have been compounded by the elevated density altitude, which also would have decreased the airplane’s takeoff performance. The pilot’s delay in aborting the takeoff left the airplane airborne but with insufficient distance and performance to clear the tree line.

Density Altitude When aircraft operate in a nonstandard atmosphere, the term density altitude is used for correlating aerodynamic performance in the nonstandard atmosphere. According to the Pilot’s Handbook of Aeronautical Knowledge (FAA-H-8083-25C), density altitude is the vertical distance above sea level in the standard atmosphere at which a given density is to be found. The density of air has significant effects on the aircraft’s performance because as air becomes less dense, it reduces: • Power because the engine takes in less air • Thrust because a propeller is less efficient in thin air • Lift because the thin air exerts less force on the airfoils Density altitude is pressure altitude corrected for nonstandard temperature. As the density of the air increases (lower density altitude), aircraft performance increases; conversely as air density decreases (higher density altitude), aircraft performance decreases. A decrease in air density means a high-density altitude; an increase in air density means a lower density altitude. Density altitude is used in calculating aircraft performance because under standard atmospheric conditions, air at each level in the atmosphere not only has a specific density, its pressure altitude and density altitude identify the same level. The computation of density altitude involves consideration of pressure (pressure altitude) and temperature. Since aircraft performance data at any level is based upon air density under standard day conditions, such performance data apply to air density levels that may not be identical with altimeter indications. Under conditions higher or lower than standard, these levels cannot be determined directly from the altimeter. Density altitude is determined by first finding pressure altitude, and then correcting this altitude for nonstandard temperature variations. Since density varies directly with pressure and inversely with temperature, a given pressure altitude may exist for a wide range of temperatures by allowing the density to vary. However, a known density occurs for any one temperature and pressure altitude. The density of the air has a pronounced effect on aircraft and engine performance. Regardless of the actual altitude of the aircraft, it will perform as though it were operating at an altitude equal to the existing density altitude. Air density is affected by changes in altitude, temperature, and humidity. High density altitude refers to thin air, while low density altitude refers to dense air. The conditions that result in a high-density altitude are high elevations, low atmospheric pressures, high temperatures, high humidity, or some combination of these factors. Lower elevations, high atmospheric pressure, low temperatures, and low humidity are more indicative of low-density altitude. Carburetor Heat According to the Aviation Maintenance Technician Handbook – Powerplant (FAA-H-8083-32B), carburetor heat is used in aircraft to prevent the formation of ice in the carburetor and carburetor normal flow air is admitted at the lower front nose cowling below the propeller spinner and is passed through an air filter into air ducts leading to the carburetor. A carburetor heat air valve is located below the carburetor for selecting an alternate warm air source (carburetor heat) to prevent carburetor icing. Carburetor icing occurs when the temperature is lowered in the throat of the carburetor and enough moisture is present to freeze and block the flow of air to the engine. The carburetor heat valve admits air from the outside air scoop for normal operation, and it admits warm air from the engine compartment for operation during icing conditions. The carburetor heat is operated by a push-pull control in the flight deck. The carburetor air ducts consist of a fixed duct riveted to the nose cowling and a flexible duct between the fixed duct and the carburetor air valve housing. The carburetor air ducts normally provide a passage for outside air to the carburetor. Applying carburetor heat to an operating engine decreases the density of the air. Air enters the system through the ram-air intake. The intake opening is in the slipstream, so the air is forced into the induction system giving a ram effect to the incoming airflow. The air passes through the air ducts to the carburetor. The carburetor meters the fuel in proportion to the air and mixes the air with the correct amount of fuel. The throttle plate of the carburetor can be controlled from the flight deck to regulate the flow of air (manifold pressure), and in this way, power output of the engine can be controlled. Improper or careless use of carburetor heat can be just as dangerous as the most advanced stage of induction system ice. Increasing the temperature of the air causes it to expand and decrease in density. This action reduces the weight of the charge delivered to the cylinder and causes a noticeable loss in power because of decreased volumetric efficiency. If icing is not present when carburetor heat or induction system anti-icing is applied and the throttle setting does not change, the mixture will become richer. In addition, high intake air temperature may cause detonation and engine failure, especially during takeoff and high-power operation. Therefore, during all phases of engine operation, the carburetor temperature must afford the greatest protection against icing and detonation. Corrective Actions To increase safety, JAARS Inc. made the following changes: o The pilot received remedial academic and flight training at the JAARS Aviation Training Center, focused on abort point philosophy and how to apply abort points considering ambiguities introduced by variable surface conditions, poorly marked runways, or when flying airplanes that only have pilot operating handbook performance numbers available. o The JAARS Aviation Fixed and Rotor Wing Knowledge, Skills, and Attributes (KSAs) document based on the International Air Transport Association/International Civil Aviation Organization Professional Pilot Competency format, modified for single pilot crew operations, was used during the remedial academic and flight training. o JAARS Waxhaw Flight Operations Manual (FOM) Chapter 11 was developed to address flight camps. The FOM contains the standard operating procedures and the organizational detail needed to determine lines of authority and responsibilities. Operational authority will remain with JAARS. o JAARS CrossVenture|Aero was developed to bring youth aviation camps in-house. o Daily pilot briefings are now conducted following a standard format. as shown in a slide presentation. o Abort points are now printed and distributed as part of the flight briefings. o Abort point markers (double orange cones) are now placed next to the runway on the right side for better instructor pilot visibility to mark the takeoff/landing abort points for each runway. o A pilot application process is now in place. Instructor pilot qualifications are now checked, and standardization is completed in accordance with standardization documents and flight sheets. o JAARS purchased dedicated aircraft for use in their CrossVenture/Aero youth aviation camps and a volunteered aircraft application process is also now in place to assure that aircraft that are not owned by JAARS which are to be used for flight camps, are subjected to an aircraft records inspection, followed by a physical aircraft inspection using aircraft inspection documents. o The JAARS Waxhaw flight department Safety Management System (SMS) is now also used to manage, safety risk and assure the effectiveness of safety risk controls for the youth aviation camps. It includes systematic procedures, practices, and policies for the management of safety risk. To promote safety at the JAARS Townsend Airport, JAARS Inc. invited Wings Over Waxhaw to participate in the JAARS SMS through mutual use of their reporting process. Review of occupant weights and