Mammoth Yosemite Airport, Mammoth, CA

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Accident occurred Sunday, March 02, 2008 in Mammoth, CA
Aircraft: Beech B36TC, registration: N243MT
Injuries: 1 Serious, 1 Minor. This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed. On March 2, 2008, about 1620 Pacific standard time, a Beechcraft B36TC, N243MT, collided with the terrain about two miles south of Mammoth Yosemite Airport, Mammoth Lakes, California. The private pilot received minor injuries, his passenger received serious injuries, and the airplane, which is owned and operated by the pilot, sustained substantial damage. The 14 CFR Part 91 personal cross-country flight, which departed the Mammoth Yosemite Airport about five minutes prior to the accident, had a planned destination of Van Nuys, California. There was no report of an ELT activation, and the pilot had not filed a flight plan. According to the pilot, three or four minutes after takeoff, the engine started to lose power, but did not completely stop running. He therefore switched fuel tanks, checked the magnetos, activated the fuel boost pump, and switched to alternate inductions air. When none of these actions seemed to help, the pilot turned back toward the airport, but soon realized that he was not going to be able to get back. He therefore elected to execute a forced landing on snow-covered terrain. He ultimately touched down with the landing gear extended in about three feet of snow. The impact with the snow resulted in crushing damage to the belly of the aircraft. ===
Accident occurred Monday, May 28, 2007 in Mammoth Lakes, CA
Probable Cause Approval Date: 7/25/2007
Aircraft: Piper PA-24-250, registration: N6744P
Injuries: 2 Uninjured.
During takeoff from the uncontrolled airport, the pilot saw another airplane on climb out that had taken off on the opposite runway. The accident pilot aborted his takeoff, and landed hard on the runway, collapsing the right main landing gear. The National Transportation Safety Board determines the probable cause(s) of this accident as follows: the pilot's failure to ensure that the runway was clear of other aircraft before takeoff. ===
Accident occurred Thursday, March 30, 2006 in Mammoth Lake, CA
Probable Cause Approval Date: 2/26/2007
Aircraft: Piper PA-24-250, registration: N6744P
Injuries: 1 Uninjured.
The commercial certificated pilot was conducting a cross-country flight under Title 14, CFR Part 91. The pilot said when he arrived at his destination airport, he did not get a green down and locked light for the landing gear, and elected to go-around. He said he cycled the landing gear up and down twice, saw the green down and locked light both times, and proceeded to land. He reported that upon touchdown, the right main landing gear collapsed, and the airplane exited the right side of the runway and struck a snowbank. The pilot stated that there were no known preaccident mechanical anomalies with the airplane. Postaccident inspection of the airplane by an independent aviation mechanic hired to repair the airplane, disclosed that the main landing gear maintenance did not appear to be in compliance with an applicable FAA airworthiness directive (AD), AD 77-13-21, Amendment 39-3093, effective December 16, 1977. That AD defines the actions/inspections necessary to maintain the landing gear in an airworthy condition, and to preclude a malfunction or collapse. A review of the airplane's maintenance logbooks indicated only partial compliance with the AD. The aviation mechanic repairing the airplane said that numerous landing gear components were worn well beyond the limits set forth in the AD and associated service letter. The National Transportation Safety Board determines the probable cause(s) of this accident as follows: The collapse of the right main landing gear during landing, which resulted in a loss of directional control and an on-ground encounter with a snowbank. A factor associated with the accident was other maintenance personnel's inadequate inspection of the landing gear system. ===
Accident occurred Sunday, January 08, 2006 in Mammoth Lakes, CA
Probable Cause Approval Date: 8/30/2007
Aircraft: Piper PA-28-235, registration: N9124W
Injuries: 2 Fatal, 1 Serious.
The airplane rolled right and collided with terrain during the initial climb after takeoff. A surviving passenger said that the takeoff and initial climb rate seemed normal. The passenger reported that about 1 1/2 to 2 minutes into the flight, the airplane, unexpectedly and without warning, went hard right and pitched straight down into the ground. Ground witnesses said that the airplane was 150 to 200 feet above the ground, and did not appear to gain any additional altitude. One witness, on an access road just north of the airport, had a profile view of the airplane during the majority of the accident sequence. He reported an "excessive" angle of attack on the takeoff. He saw the nose pitch down, and thought the airplane was about 100 feet above the ground. The witness then saw the nose pitch up again, increasing the angle of attack. The pitch attitude was steep; the witness said he was able to see the tops of the wings. He stated that the airplane flew straight ahead under controlled conditions, but appeared to be "mushing" through the air. He lost sight of the airplane as he rounded a bend in the road. When he saw the airplane again it was in a left descending spiral. Investigators found no anomalies that would have precluded normal operation of the airframe or engine. The National Transportation Safety Board determines the probable cause(s) of this accident as follows: the pilot's failure to maintain an adequate airspeed resulting in a stall/spin. ===
Accident occurred Monday, December 12, 2005 in Mammoth Lakes, CA
Probable Cause Approval Date: 8/30/2007
Aircraft: Beech A23, registration: N3590R
Injuries: 2 Fatal.
The airplane collided with flat desert terrain following an in-flight loss of control. A witness about 1 mile south of the accident site heard a rough running engine, and looked up to see what it was. As the airplane traveled overhead, he heard the engine "popping/backfiring," which lasted about 3 seconds, and then the engine quit. He then saw the airplane "dip" to the right, in a "tumbling motion." The witness indicated that it was like a somersault with the nose dropping and the tail coming over the top. He saw about 2 to 3 revolutions of the airplane, which lasted a total time of about 8 seconds, and then the airplane dropped below tree level and collided with the ground. The witness reported that it was somewhat cloudy in the area, but the airplane was below the clouds. When he arrived at the accident site to render aid, he reported there was no frost/ice on the wings, and that it was not cold enough for the formation of frost/ice. Witnesses at the departure airport reported that the engine sounded like the exhaust system was leaking very badly or that either the exhaust or muffler was loose. An engine test run could not be conducted due to displacement of the crankshaft caused by the nose-down impact. An engine teardown revealed no discrepancies in the engine core or in the accessories that would have precluded normal operation. The National Transportation Safety Board determines the probable cause(s) of this accident as follows: a loss of engine power for undetermined reasons, and, the failure of the pilot to maintain an adequate airspeed while maneuvering following the loss of power, which resulted in a stall/spin. ===
Accident occurred Sunday, March 23, 2003 in Mammoth Lakes, CA
Probable Cause Approval Date: 9/1/2004
Aircraft: Ryan Navion, registration: N5291K
Injuries: 1 Minor, 2 Uninjured.
The airplane veered off the runway during the landing roll and collided with terrain and high vegetation. At 1152, the airport's airport automated weather observation station (AWOS) was reporting winds at 200 degrees, 15 knots gusting to 25 knots. The pilot reported that the airport advisory conditions relayed to him over the CTAF were winds of 250 to 270 degrees, 15 knots gusting to 25 knots, and runway 27 was in use. The pilot also observed the airport windsock showing winds from the west/northwest. During the landing sequence, and after the landing gear contacted the runway, the pilot experienced a "substantial and unexpected gust of wind" from the southerly direction. The left wing raised and the airplane veered off the right side of the runway. The pilot applied rudder and aileron to compensate before deciding to attempt a go-around. The airplane continued to rise in level flight before he "experienced a sensation of downward force." The airplane came to rest in sagebrush approximately 210 feet north of the parallel taxi way. The National Transportation Safety Board determines the probable cause(s) of this accident as follows: the pilot's inadequate compensation for the wind conditions and failure to maintain directional control during the landing roll. A factor was the gusty crosswind. ===
Accident occurred Wednesday, May 22, 2002 in Mammoth Lakes, CA
Probable Cause Approval Date: 7/23/2003
Aircraft: Robinson R22 Beta, registration: N7194J
Injuries: 2 Fatal.
The helicopter impacted trees and the rising mountainous terrain approximately 7.8 miles from the airport. Prior to departure, the helicopter's main and auxiliary fuel tanks were topped off with fuel. Witnesses observed the pilot and passenger board the helicopter, and reported that the engine start was normal. The engine idled for two minutes, the rpm increased to "full power". The helicopter lifted off the ground "approximately 3 to 4 feet, and then set down very controlled." The engine rpm decreased for a few seconds, then back to "full power". The helicopter lifted off the ground, turned to the west, and moved about 30 feet to "the yellow X (a closed taxiway), and set down very hard." One witness stated that "[it] seemed like they had difficulty trying to get off the ground." After a few seconds, the helicopter lifted off again dragging the forward portion of the skids on the taxiway, departed to the west and "did not gain a lot of altitude." The maximum allowable gross weight of the helicopter was 1,370 lbs. Considering the occupants, miscellaneous baggage, and full of fuel, the helicopter's gross weight, at the time of departure, was 1,459.25 lbs. The density altitude at the departure airport and the accident site was calculated at 8,702 feet and 10,681 feet, respectively. According to the approved rotorcraft flight manual, the in-ground-effect (IGE) hover ceiling versus gross weight, and the out-of-ground-effect (OGE) hover ceiling versus gross weight performance limits were not available beyond 1,370 lbs. gross weight. The performance specifications had been approved up to the maximum allowable gross weight. The engine was test run on the airframe, and no anomalies or discrepancies were noted. The National Transportation Safety Board determines the probable cause(s) of this accident as follows: The pilot's poor decision to continue the flight into the rising mountainous terrain, and subsequent failure to maintain clearance with the trees. Contributing factors were rising mountainous terrain, the high density altitude, and the exceeded weight and balance and performance capability of the helicopter. ===
Accident occurred Monday, January 21, 2002 in Mammoth Lakes, CA
Probable Cause Approval Date: 9/30/2003
Aircraft: Beech B36TC, registration: N6427N
Injuries: 5 Uninjured.
During takeoff in a quartering left crosswind, the left wingtip dropped and contacted the runway surface. The pilot reported that two other aircraft, one of similar weight and size, had departed ahead of him as he performed his run-up. The windsock indicated the wind was variable from down the runway to a 45-degree left crosswind at 15 to 20 knots. During his takeoff roll, as he rotated the airplane for liftoff, the airplane encountered a "strong side gust," which caused the airplane to yaw into the wind, one wing to lift, and the other to drop and contact the runway. Following the wingtip contact with the runway, the pilot aborted the takeoff and brought the airplane to a stop on the remaining runway. The surface wind, recorded by the Automated Weather Observing System (AWOS) 48 minutes after the accident, was a 70-degree left crosswind at 18 knots with gusts to 31 knots. The National Transportation Safety Board determines the probable cause(s) of this accident as follows: The onset of variable, gusty, crosswind conditions at the time of departure and the pilot's inadequate and improper compensation for the crosswind conditions. ===
Accident occurred Monday, January 21, 2002 in Mammoth Lakes, CA
Probable Cause Approval Date: 9/29/2004
Aircraft: Cessna 206H, registration: N72635
Injuries: 1 Uninjured.
The airplane impacted a snow bank and nosed over after the pilot lost control of the airplane during a landing roll in 45-knot gusty crosswind conditions. According to the pilot, he obtained numerous weather updates prior to departing and during the flight. All of the reports included notification of gusty wind conditions. The pilot obtained one more wind report prior to landing on runway 27, which informed him that the wind was from 210 degrees at 25 knots with gusts to 45 knots. The pilot continued with the landing and during the rollout, at 30 knots, a gust of wind lifted the left wing, blowing the airplane to the right into a snow bank. The pilot reported placing the control yoke in the full aft position (up elevator) after the original upset, when the airplane was encountering a tailwind condition. The airplane then hit the snow bank and nosed over. The airplane's Pilot Operating Handbook instructs pilots to put the elevator in a down position when encountering a tailwind condition. A review of the Airport/Facility Directory, Southwest U. S., revealed a caution to pilots regarding gusty wind conditions and wind shear. The National Transportation Safety Board determines the probable cause(s) of this accident as follows: the pilot's inadequate compensation for the gusty crosswind conditions, which resulted in a loss of aircraft control and nose over during landing roll. ===
Accident occurred Saturday, July 21, 2001 in Mammoth Lakes, CA
Probable Cause Approval Date: 5/28/2002
Aircraft: Cessna R172K, registration: N736YR
Injuries: 2 Serious.
The pilot stated that while en route from Van Nuys to Mammoth Yosemite (MMH) via the Friant VOR radial 023, he entered a canyon and later realized that he had entered the wrong one. He said that the canyon was closed and above his altitude. He also stated that he was experiencing moderate turbulence from the time he entered the canyon up to the accident. The pilot began a "full power climb" at 75 knots in an attempt to clear the ridgeline at the end of the canyon. When he realized that he would not clear the terrain, he began a steep left turn. During the turn, the stall warning was activated and the pilot lowered the nose and shallowed the bank angle. He stated that the airplane struck trees on the top of the canyon edge, tearing off the left wing with the airplane striking the ground in a level attitude. He stated that, "The engine was working properly and all the gauges were in the green." According to the San Francisco sectional chart, the Mammoth Pool Reservoir, which is 55 nautical miles southwest of the MMH airport on a magnetic bearing of 213 degrees, is directly under the 023-degree radial of the Friant VOR. The pilot stated that when he saw the reservoir, he turned east toward the MMH airport. The magnetic course from the reservoir to the MMH airport was 033 degrees, or a northeasterly direction. There was a canyon leading northeast from the Mammoth Pool Reservoir along the Friant 023-degree radial, which is also Victor 230. The canyon terminated at Mammoth Lakes, which is 11 miles due west of the MMH airport. Had the pilot followed Victor 230 until reaching the Mammoth Pools, then turned to an easterly heading, he would have been proceeding directly to the airport. The National Transportation Safety Board determines the probable cause(s) of this accident as follows: The pilot's inadequate in-flight planning and his failure to maintain sufficient altitude above the terrain. Factors were the high terrain and the blind canyon.



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