Minden, NV, USA
N418AP
AMS Flight Carat A
The motorized glider broke apart during a personal flight. The pilot told an acquaintance at the airport that he intended only a short flight. The acquaintance noted that the pilot did not have oxygen and offered to loan the pilot some; however, the pilot reiterated that he only intended on doing a short local flight. The glider was not equipped with gyroscopic flight attitude reference instruments. Witnesses reported hearing an engine rev up and down prior to hearing a loud bang. Several of the witnesses observed the aircraft falling from the base of the clouds with separated wings and debris following behind. Review of the weather in the area of the accident revealed there were unstable wave conditions that were reported as rapidly changing by another glider pilot. The pilot witness said the wave conditions were not very strong, nor was the mountain wave very well established. The air gap between the mountain cap cloud and the downwind lenticular clouds was rapidly closing and opening, creating an area that one moment was free of clouds and the next moment completely obscured. There were also reports of moderate turbulence in the accident area and freezing levels were reported above 9,200 feet in clouds and precipitation. The cloud tops were reported to be between 15,000 and 16,000 feet, while the bases were between 8,000 and 9,000 feet. Review of the glider's radar data revealed it was flying along a southerly heading at 14,600 feet mean sea level (msl). The glider's radar track then depicted the glider making a turn toward the northeast and enter two spiraling right turns with a rapid descent. The glider descended from 14,600 feet to 9,200 feet in 1 minute, which was the last radar return received. Post-accident examination of the composite wings revealed the right wing spar failed in two locations while the left spar failed in four locations. All of the fractures were consistent with an overload failure and were not associated with any obvious manufacturing defects. No preimpact anomalies were noted with the flight controls. The never exceed and maneuvering speeds of the glider were 135 and 100 knots, respectively. The limit load factor was established at +5.3/-2.65. The pilot did not wear a parachute due to previous back injuries and pain. He had not had a current medical certificate for more than 7 years prior to the accident, and review of his medical history revealed he had a number of medical conditions that could have resulted in an incapacitation event; however, the autopsy results were inconclusive in determining the likelihood of this possibility. He was also taking some potentially impairing medications such as brompheniramine and diazepam; however, no blood samples were available, and it was not possible to determine precisely when the drugs might have been used nor the level of potential impairment at the time of the accident.
HISTORY OF FLIGHT On October 23, 2004, approximately 1240 Pacific daylight time, an AMS Flight Carat A motorized glider broke apart in flight and impacted terrain near Minden, Nevada. The glider was registered to, and operated by, the pilot. The airline transport pilot, the sole occupant, was fatally injured. The glider was destroyed. Visual meteorological conditions prevailed, and a flight plan was not filed for the local flight. The flight departed the Minden-Tahoe Airport, Minden, Nevada, approximately 1220. According to an acquaintance of the pilot, who was also a glider pilot, the accident pilot spoke with him while they were on the ramp area at the Minden-Tahoe Airport. The pilot indicated he was going flying and the acquaintance stated that the waves were closing up. The pilot said it would be a short flight. The acquaintance was familiar with the pilot and his aircraft, and was aware that his oxygen tank was not filled. He offered his oxygen, but the pilot declined, again indicating that it was going to be a short flight. The acquaintance further stated that the pilot did not have a parachute with him. The acquaintance additionally noted that he observed a gap between the wave clouds, which was opening and closing at a noticeably rapid rate. A review of the aircraft's radar data obtained from Reno's Airport Surveillance Radar (ASR-9) revealed the glider initially flew northbound, parallel to, but west of, U.S. route 395 [route 395 is a north-south route that runs between Minden and Carson City, Nevada]. As the glider reached the southern end of Carson City, it reversed course and traveled southbound on the east side of route 395 for about 3.5 nautical miles. The glider's radar track then shifted west until it was over route 395. The track continued south over route 395 for about 1.5 nautical miles before it veered to the east-northeast. The last 10 radar returns depicted an aircraft track consisting of two, right, 360-degree spiraling turns with the following associated altitudes: 1. 1244:45 14,600 feet 2. 1245:04 14,200 feet 3. 1245:09 13,700 feet 4. 1245:14 12,800 feet 5. 1245:18 12,100 feet 6. 1245:23 12,100 feet 7. 1245:28 12,100 feet 8. 1245:32 11,400 feet 9. 1245:37 10,400 feet 10. 1245:42 9,200 feet Douglas County sheriff's office personnel interviewed seven witnesses regarding their observations of the accident. Three of the witnesses mentioned hearing an engine rev up and down prior to hearing a loud bang. All of the witnesses heard a loud bang. Four looked up and observed an airplane falling out of the base of the clouds. One of the witnesses estimated the cloud height to be approximately 5,000 feet. This same witness indicated that as the fuselage fell out of the cloud, one of the wings remained attached until approximately 3,000 feet. All of the witnesses described seeing debris flutter to the ground following the impact of the fuselage. PERSONNEL INFORMATION The pilot held an airline transport pilot certificate with single engine land, multiengine land, and instrument airplane ratings. Under the airline transport pilot certificate, the pilot also acquired type ratings in Boeing 737, 757, and 767 transport category airplanes. In addition, he had commercial pilot privileges for gliders. The pilot's family was unable to locate his logbooks. He was a retired pilot for United Airlines, and according to an insurance application dated July 9, 2004, he had accumulated a total of 12,000+ hours of flight time. His application indicated he accrued a total of 202 glider flight hours, of which 169 hours were listed as motorglider. According to acquaintances of the pilot, he accumulated about 85 hours in the accident glider make and model [totaling approximately 254 motorglider hours]. The pilot did not hold a current Federal Aviation Administration (FAA) issued medical certificate. His last medical was a first-class medical certificate, which was issued on July 17, 1995. According to 14 CFR Part 61.23 (b), Operations Not Requiring a Medical Certificate, a person is not required to hold a valid medical certificate if they are exercising the privileges of a pilot certificate with a glider category or balloon class rating. The FAA defines a glider as a heavier-than-air aircraft, that is supported in flight by the dynamic reaction of the air against its lifting surfaces and whose free flight does not depend principally on an engine. AIRCRAFT INFORMATION The single-seat, motorized, composite glider, serial number CA012, was type certificated in Germany as a motorglider. However, since it has not yet been approved for a standard certification in the U.S., the pilot obtained a special airworthiness certificate in the form of an experimental (glider) designation from an FAA designated airworthiness representative (DAR) for the purpose of "exhibition/air racing." According to a letter written by the pilot, dated September 7, 2004, the glider was "intended to be flown in pursuit of Soaring Society of America (SSA) and Federation Aeronautique International (FAI) records and sponsored contests. In addition, the glider will be flown for proficiency and practice for these events. Also, as a new type of factory built motor glider, the machine will be statically displayed at air shows and aircraft conventions." The letter terminated by indicating, "all flights in this glider will be operated in day VFR [visual flight rules] under Visual Flight Rules." There are 11 registered AMS Flight Carat A gliders in the U.S. as of this report's writing. The AMS Flight Carat A glider is constructed from fiber reinforced plastic (FRP) composites, featuring aileron, airbrake, elevator, and rudder flight controls in a T-tail configuration (with fixed horizontal stabilizer and two-piece elevator). The manufacturing process uses a lay-up of composite material plies and epoxy resins. The flight controls are all push-pull tubes except for the rudder, which is controlled via cables. The airbrakes are a single panel mounted aft of the main spar, but inboard of each aileron. The airbrakes consist of a red metal panel that when deployed disrupts the flow of air over the wings thereby inducing drag. When stowed, the airbrakes are hidden beneath the surface of the wings by a composite cover that fairs the slot opening for the airbrake with the upper surface of the wing. During deployment the airbrakes extend above the surface of the wing; an action controlled by push/pull tubes that are connected to the cockpit controls. The glider utilizes two composite wings that are interconnected by a wing pin located under the seat pan. The wing roots slide into slots located on the bottom sides of the glider. The root of each spar contains a stainless steal pin (oriented parallel to the lateral axis of the glider) that slides into a cylindrical fitting located in the opposite wing. When those wing root pins are inserted into the other wing, the stainless steal locking pin (oriented along the longitudinal axis of the glider) can then slide into both wing spars, locking them together in the center of the glider. In addition, there is a fore and aft lift pin for each wing (also oriented parallel to the lateral axis of the glider) that slide into receptors located in the fuselage. With the wings connected to each other and the fuselage, the aileron and spoiler flight controls are automatically connected and engaged via a roller and roller adapter connection (no additional flight control connection is required). The glider's wingspan equated to 49.2 feet and the total wing area amounted to 114 square feet. Information provided by the manufacturer indicated that the airfoil had an aspect ratio of 21.3. The wing loading was 7.5 to 9.1 pounds per square foot and the limit maneuvering load factor was +5.3 g and -2.65 g. The glider's maneuvering speed was 100 knots with a never exceed speed of 135 knots. The main I-beam wing spars are comprised of a foam core web section sandwiched on each side by glass fiber material. The spar caps on the inboard section of wing are constructed from a carbon fiber and divert to a glass fiber spar cap construction for the outboard sections of the wings. The spar caps are primarily made of unidirectional carbon/graphite epoxy material and the shear webs are made of ±45° fiberglass. The skin panels are sandwich structures; foam core and glass fabric epoxy face-sheets. The skin panels consists of many layers of ±45° fabric to resist twisting and serve as a "torque box." The horizontal stabilizer (with elevator attached) connects to the vertical stabilizer via an automatic locking bolt. The elevator is connected to the elevator control system via two male pins, which slide into orifices manufactured into the elevator control tube located in the horizontal stabilizer. The glider was equipped with a 54-horsepower Sauer SE 1800 H1S engine (serial number 267). It was propelled by a composite two-blade propeller that folded forward against the air stream by means of two damping gas springs when the engine is shutoff at speeds below 48 knots. When the engine is started, centrifugal forces open the propeller. The glider also utilized retractable main landing gear that fold forward toward the aft end of the engine. The airplane was not equipped with gyro instruments. According to acquaintances of the pilot, he purchased the glider in August 2004, and accumulated approximately 85 hours of flight time in the accident glider. Aircraft maintenance records were not located for the glider or its engine. METEOROLOGICAL INFORMATION At 1153, the Lake Tahoe Airport (TVL) weather observation facility, located approximately 12 miles southwest of the accident site, reported the wind from 170 degrees at 12 knots with gusts to 19 knot;, visibility 10 statute miles in light rain; broken clouds at 2,100 feet above ground level (agl) and overcast clouds at 2,500 feet agl; temperature 4 degrees Celsius; dew point 2 degrees Celsius; and an altimeter setting of 29.98 inches of mercury. The elevation of TVL is 6,264 feet mean sea level (msl) and the accident site elevation was recorded at 4,635 feet msl. A National Transportation Safety Board meteorologist examined the weather around the accident site, near the time of the accident. Surface observations revealed that light rain existed in the region. Observations from Reno, Nevada, also noted the presence of Altocumulus Standing Lenticular Clouds. A weather station 2 nautical miles away from the accident site reported surface wind gusts between 16 and 17 knots about the time of the accident. Data from the Reno weather radar showed scattered echoes across the region ranging generally from 5 to 25 decibels; however, measurable echoes were not noted near the glider's flight track during the flight or near the time of the upset. Upper air data interpolated to the approximate time of the accident indicated westerly to southwesterly winds at Reno, with a freezing level near 9,200 feet msl. RAOB, a program used to analyze upper air data, suggested a potential for mountain wave activity in the area, while visible satellite imagery showed cloud-banding features east of Lake Tahoe. Prior to the accident, pilot reports near Reno noted light to moderate turbulence in the area and light icing. There were AIRMETs (airmen meteorological information) for mountain obscuration, icing, and turbulence valid at the time of the accident. These AIRMETs included the accident location and were issued at 0645 on October 23 and were valid until 1300 on the same day. AIRMET Sierra, which highlights instrument flight rule (IFR) conditions and mountain obscuration, indicated that mountains would occasionally be obscured by clouds, precipitation, or mist, while AIRMET Zulu suggested the presence of occasional moderate rime or mixed icing in cloud and precipitation between the freezing level (about 9,200 feet) and 20,000 feet. Finally, AIRMET Tango indicated the existence of occasionally moderate turbulence below 14,000 feet due to moderate westerly to southwesterly flow over rough terrain. Another pilot, who was providing glider instruction at the time of the accident, reported that mountain wave conditions existed. He added that the conditions were not very strong and there was a lot of moisture in the air. The pilot described a mountain cap cloud followed by an air gap to the east and other lenticular clouds downwind of the gap (further to the east). He added that the mountain wave was not a very well established and the gap between the clouds was rapidly changing. The pilot elected not to fly above 14,000 feet so their glider could descend in the event the clouds closed up. His flight lasted about 1.5 hours and he heard the accident pilot about 30 minutes into the flight. The instructor pilot described the clouds with bases at 8,000 to 9,000 feet msl and tops at 15,000 to 16,000 feet msl. He and his student ended their flight because the gap was closing in and they did not want to get caught above the clouds. WRECKAGE AND IMPACT INFORMATION The FAA inspector and sheriff personnel recorded the following debris at the following locations utilizing a global positioning system (GPS): Main Fuselage 39 degrees 05.021 minutes north 119 degrees 45.012 minutes west Left Inboard Wing 39 degrees 05.510 minutes north 119 degrees 44.903 minutes west Left Outboard Wing 39 degrees 05.602 minutes north 119 degrees 44.802 minutes west Right Inboard Wing 39 degrees 05.446 minutes north 119 degrees 44.931 minutes west Right Outboard Wing 39 degrees 05.359 minutes north 119 degrees 45.011 minutes west Photographs taken at the accident site indicated that the empennage came to rest adjacent to the fuselage/engine. The empennage was separated from the fuselage just aft of the cockpit and fractured just forward of the vertical stabilizer. The horizontal stabilizer came to rest adjacent to the vertical stabilizer, but was separated. Control continuity was confirmed from the cockpit rudder pedals back to the rudder; however, the cables were cut to facilitate wreckage recovery/transport. The glider wreckage was recovered to a secure location for further examination. On November 19, 2004, the Safety Board investigator-in-charge examined the wreckage in a closed hangar in Minden. The wreckage was laid out as it would normally be assembled. The left wing spar separated in four sections: 1.) About 73 inches outboard from the wing root (near the inboard end of spoiler; the wing remained attached at this spar fracture point via wing skin and the spoiler control rod). 2.) About 164 inches outboard from the wing root (the wing remained attached at this spar fracture point via wing skin). 3.) About 228 inches outboard from the wing root (the wing separated entirely at this fracture area). 4.) About 280 inches outboard from the wing root at the vertical winglet attach point (the winglet separated from the outboard wing section). The right wing spar was separated in two sections: 1.) About 173 inches outboard from the wing root (near the outboard end of the aileron; this was a complete separation of wing spar and wing skin). 2.) About 280 inches outboard from the wing root at the vertical winglet attach point (the winglet separated from the outboard wing section). In addition, a large skin panel extending from the inboard aileron area to the wing root, separated from the bottom side of the right wing. Examination of the spar fracture areas revealed irregular separation features. No defects relating to the manufacturing process were visibly noted near the fracture areas. The wing joining pins and their cylindrical fittings were examined. Both cylindrical pin receptacles were forced out toward the bottom side of each wing. The composite structure that would normally surround the cylindrical fittings was torn and distorted toward the bottom of each wing. The right wing's lift pins were examined and the following was noted: the aft pin was distorted up and forward, while the forward pin was also bent upward. The left wing's lift pins were exami
the pilot's likely inadvertent entry into instrument meteorological conditions created by the rapidly changing cloud conditions that resulted in his spatial disorientation and exceeding the glider's ultimate design loads while in a spiral dive, which resulted in the overload failure of the wings.
Source: NTSB Aviation Accident Database
Aviation Accidents App
In-Depth Access to Aviation Accident Reports
