A Citation 501 pilot and his four passengers were killed on March 15, 2012, when what should have been a routine fair weather landing at Macon County, N.C., Airport (1A5) turned sour after two unstabilized VFR approaches.
Two witnesses — one of them a pilot — watched the Citation approach Runway 25 from their vantage point on the ramp. The airplane was high during the approach, they told investigators. The pilot performed a go-around, and made left turns for another approach.
During the second attempt, the airplane seemed high and its approach angle seemed steep. The approach angle steepened on short final, and the Citation nosed-down toward the runway.
The nosewheel touched down before the mains approximately halfway down the 5,000-ft.-long, 75-ft.-wide runway. When the main gear contacted the surface, the airplane bounced and the witnesses heard the engine noise increase. Finally, the Citation banked right and the right wing caught the ground. The airplane flipped over off the right side of the runway and burned.
Weather at the time was fine — wind from 260 deg. at 3 kt.; sky clear; visibility, 10 mi.; temperature, 23C; dew point, 7C; altimeter, 30.28 in. of mercury. Airport elevation is 2,020 ft.; it's located in the Iotla Valley of the Great Smoky Mountains about 4 mi. from Franklin, N.C. Wooded hills — some of them 1,000 ft. above airport elevation — are within a few miles north and south of the airport.
The airport is served by a GPS approach and sees plenty of business jet traffic. Pilots with local knowledge report that the view on approach can be somewhat disconcerting to first-time arrivals because of the surrounding hills. A search of the FBO records and the accident pilot's log indicated that he had never been into 1A5 before the accident.
A nosewheel landing followed by a bounce and cartwheel is unusual for turbine airplanes and almost unheard of in small, straight-wing jets. Investigators made a close inspection of the wreckage looking for mechanical clues.
The airplane had come to rest in a grassy area, about 50 ft. off the right side of the runway, approximately 4,250 ft. beyond the approach end of Runway 25. The wreckage was inverted and oriented about a magnetic heading of 350 deg. Investigators found 100 ft. of skid marks about 2,300 ft. beyond the approach end of the runway, consistent with the left and right main landing gear tires. Another 55-ft. skid mark was observed about 250 ft. beyond the first skids, which was consistent with the left main landing gear tire. The post-crash fire consumed most of the cockpit and cabin. The horizontal stabilizer, vertical stabilizer, elevator and rudder remained intact but were charred. The left side of the elevator had partially separated from the horizontal stabilizer. The left wing inboard section was consumed by fire. The left wing outboard section was crushed and charred. A section of left aileron remained partially attached to the outboard left wing. With the exception of one flap hinge remaining, the left flap had separated from the left wing. The left main landing gear had also separated from the left wing. The right wing inboard section had separated from the fuselage and was crushed and charred. The outboard section had been consumed by fire. The right aileron separated and was found near the left wing. A section of right flap remained attached to the right wing. The right main landing gear remained attached to the right wing.
The nose gear separated and the nosewheel and tire assembly was located on the runway, adjacent to the main wreckage. Examination of the landing gear, landing gear selector handle, flaps and flap selector handle revealed that the landing gear and flaps were in the fully extended position. Emergency medical service personnel reported that they had to cut control cables and move the right wing to gain access to the occupants. Control continuity was confirmed from the elevator, through push-pull tubes and a bellcrank, to control cables near the aft cabin area. At the aft cabin area, one cable was cut and the other cable turnbuckle had melted. The cables then extended from that point to the forward cockpit area.
Continuity also was confirmed from the rudder through cables to the rudder pedals. The rudder cables had also been cut near the aft cabin area. Aileron control continuity was confirmed from their respective bull-wheels at the ailerons, through cables to the aileron sector assembly at the aft cabin area. The cables had been cut near that point and continued to extend to the forward cockpit area. Measurement of the elevator trim jackscrew revealed an approximate 13-deg. elevator trim tab down position. Measurement of the rudder trim jackscrew revealed an approximate neutral rudder tab position. A surprise finding was the right thrust reverser that was found in the deployed position. Penetration damage on the cowling underneath the reverser was consistent with the right thrust reverser being deployed during the impact sequence. The right throttle lever was observed in the aft position, near the flight idle stop, with its thrust reverser lever in the deploy position.
The left engine thrust reverser was found in the stowed position. The left throttle lever was in a mid-range position with its thrust reverser lever in the stow position.
The reversers are activated by pilot operation of the thrust reverser throttle levers and deployed by hydraulic pressure supplied by an engine-driven pump directed to the drive actuators. The reversers can only be deployed when the primary throttle levers are in the idle thrust position and the airplane is on the ground as sensed by either of the main gear squat switches. When commanded, the thrust reversers fully deploy within 1.5 sec. After deployment, engine power can be increased by moving the thrust reverser throttle levers aft for maximum reverse thrust. Stops installed on the thrust reverser levers are set to 90% N1 at sea level on a standard day. To stow the thrust reversers, the pilot can move the reverse thrust levers through the idle reverse detent to the stow position. The airplane was also equipped with an emergency stow switch for each thrust reverser, located on the cockpit glareshield. Investigators noted that a review of a Cessna 500/501 operation manual revealed: "Single-engine reversing has been demonstrated during normal landings and is easily controllable."Teardown examination of both engines showed that their respective low-pressure compressor fan blade tips were bent opposite the direction of rotation and sand had found its way onto the high-pressure turbine blades, consistent with the engines operating at the time of impact. The examination found no evidence of preimpact mechanical anomalies that would have precluded normal engine operation.
The flight had departed Venice, Fla., Municipal Airport at 1149 for a 2-hr. flight. The pilot had filed an IFR flight plan. The en route phase was routine. At 1340, the airplane was at 7,300 ft. when an Atlanta Center controller approved a frequency change to the local airport common traffic advisory frequency (CTAF). The pilot acknowledged the frequency change, and no further communication was received by center controllers.
The pilot was 62 years old. He held a private certificate with ratings for airplane single- and multiengine land, and instrument airplane. He had a type rating in the Citation 501. Investigators said a review of the pilot's logbook revealed that he had accumulated a total flight experience of approximately 1,159 hr. About 185 hr. were in the accident airplane — all flown during the previous two years. He had flown the Citation about 8 hr. and 16 hr. during the 30-day and 90-day periods preceding the accident.
Review of performance data for the make and model airplane revealed that at an estimated landing weight of 9,500 lb., the airplane required a landing distance of approximately 2,180 ft. on a dry runway, without wind factored. The distance also assumed a landing reference speed (Vref) of 99 kt., a temperature of 25C and no use of thrust reversers.
Thenoted that the pilot had been involved in a prior accident on March 12, 2006, when he was PIC of a Piper PA32-301 that departed the side of a runway while landing. The probable cause of that accident was "the failure of the pilot to maintain directional control during the landing roll with a crosswind, resulting in collapse of the nose landing gear."
In its final report on the Citation accident, the NTSB noted, “Although manufacturer data revealed single-engine reversing has been demonstrated during normal landings and is easily controllable, the airplane had already porpoised and bounced during the landing. The pilot's subsequent activation of only the right engine's thrust reverser would have created an asymmetrical thrust and most likely exacerbated an already uncontrolled touchdown. Had the touchdown been controlled, the airplane could have stopped on the remaining runway or the pilot could have performed a go-around uneventfully.”
The Safety Board determined the probable cause(s) of this accident was “the pilot's failure to achieve a stabilized approach, resulting in a nose-first, bounced landing. Contributing to the accident was the pilot's activation of only one thrust reverser, resulting in asymmetrical thrust.”
The Flight Safety Foundation's Approach and Landing Accident Reduction Tool Kit reports that unstabilized approaches were a causal factor in 66% of the approach and landing accidents and serious incidents worldwide in the decade ending in 1997. It determined that “High energy approaches (i.e., high/fast) resulted in loss of aircraft control, runway overruns and runway excursions and contributed to inadequate situation awareness in some CFIT accidents.”
The full report and a checklist on recommended elements of a stabilized approach can be found at www.flightsafety.org/files/alar_bn7-1stablizedappr.pdf (FSF ALAR Briefing Note 7.1 — Stabilized Approach).