Aviation Accident Summaries

Aviation Accident Summary SEA99GA085

ENTERPRISE, OR, USA

Aircraft #1

N9458H

Cessna 182R

Analysis

The flight was part of a U.S. Air Force-sponsored mountain flying training clinic. The planned flight route included a contour search pattern into a series of drainages along the Minam River valley, including the canyon in which the accident occurred. A trainee at the clinic who flew the accident flight route with the accident flight 'mentor' on the accident aircraft's previous flight reported that he had refused to fly into most of the drainages on the route, believing that the aircraft did not have sufficient climb capability or space to turn around in the drainages. This trainee reported that the route segment where the accident occurred was flown at 90 knots with 10 degrees of flaps. When the accident flight failed to return to base at the scheduled time and contact could not be established with the aircraft, a search was begun. The aircraft wreckage was located approximately two days later, with both occupants found fatally injured at the accident site. A chart of the planned flight route showed that at the approximate location of the crash site, a 135-degree turn was to be made to climb out, exit the training route and return to base. The accident site, located at the 5,400-foot level on sloping terrain, was approximately 1/2 mile beyond the depicted turn point (i.e., further into the canyon than planned.) Investigators found damage and impact signatures at the accident site consistent with an uncontrolled, relatively low-speed impact with the terrain, and the aircraft's flaps at 10 to 15 degrees, but no evidence of pre-impact mechanical problems with the aircraft. Based on a METAR observation taken about the estimated time the crash occurred, density altitude at La Grande, Oregon (approximately 19 nautical miles from, and 2,700 feet below the accident site) was computed to be approximately 5,000 feet.

Factual Information

HISTORY OF FLIGHT On June 12, 1999, approximately 1635 Pacific daylight time, N9458H, a Cessna 182R airplane registered to Civil Air Patrol (CAP) Inc. of Montgomery, Alabama, and operated by the Oregon Wing of the CAP as a public-use mountain search-and-rescue (SAR) training flight, departed Baker City, Oregon, on a scheduled 1.5-hour mission. The aircraft failed to return to Baker City at the scheduled time, and a search for the aircraft was initiated. The aircraft wreckage was located on June 14, 1999, in the Chaparral Creek canyon in the Eagle Cap Wilderness of the Wallowa-Whitman National Forest, approximately 12 nautical miles west-southwest of Enterprise, Oregon. The aircraft was found to be destroyed by impact forces and fire, and both aircraft occupants, consisting of a commercial pilot-in-command and an additional commercial pilot acting in the capacity of a mountain flying "mentor", were found fatally injured. Visual meteorological conditions were reported at Baker City and La Grande, Oregon, during the scheduled time frame of the accident flight, and a company visual flight rules (VFR) flight plan had been filed. There was no report of an emergency locator transmitter (ELT) activation. The accident flight took place as part of a mountain flying training clinic being conducted by the CAP's Oregon Wing. The training clinic was assigned a U.S. Air Force training mission number, TOR0040-99. The accident flight was the pilot-in-command's second flight of the day (the pilot-in-command was a mountain flying trainee at the clinic), and the mentor's third flight of the day. The assigned route of flight, designated the "Red Route", included a contour search pattern into a series of canyons along the east bank of the Minam River (including the Chaparral Creek canyon), which proceeded in a generally south-to-north direction down the Minam River toward the accident area. A copy of a CAP chart depicting the Red Route indicated that in the vicinity of the accident site, a left turn of approximately 135 degrees was to be made to exit the route and return to Baker City. The accident site was approximately 1/2 mile north of the planned turn location (i.e., further into the canyon than the depicted ground track.) According to route planning information furnished by the CAP, the Red Route was identified as the third hardest of five routes planned for use during the training clinic. The route description included the following: "Val semi U shape, room to turn at <1000' Val deep but wide, no need for 360 turns...." The route planning information indicated that elapsed flight time at the route exit point could be from 32 minutes to 1 hour after takeoff from Baker City. According to the Alert Notice (ALNOT) issued for the accident flight, the estimated time en route for the flight was 1 hour and 30 minutes, with an estimated time of arrival back at Baker of 1805. The ALNOT was issued June 12, 1999, at 2017. The accident occurred during the hours of daylight at 45 degrees 21.3 minutes North and 117 degrees 33.6 minutes West. PERSONNEL INFORMATION The pilot-in-command, the trainee on the accident flight, held a commercial pilot certificate with airplane single-engine land and instrument airplane ratings. He also held advanced and instrument ground instructor ratings. He held a second-class medical certificate issued October 27, 1998, with a restriction requiring that the pilot must have available glasses for near vision. CAP reported that the pilot had 1,350 hours total time including 1,347.5 hours in single-engine airplanes and 1,200 hours as pilot-in-command. According to documentation furnished by CAP, the pilot held a CAP aeronautical rating of Senior Pilot, and was a qualified mission pilot. CAP records indicated that the pilot completed an FAA flight review on November 10, 1998. CAP records also showed that he satisfactorily completed a CAP recurrent pilot flight evaluation in a Cessna 182R aircraft on April 13, 1999, and a CAP mission pilot checkout on September 11, 1998, in what was described on the checkout record as a "well planned and flown check flight." The September 11, 1998, mission pilot checkout form indicated that the checkout included evaluation of mountainous terrain procedures including establishing search altitude, contour search procedures, and canyon search procedures. CAP also reported that the pilot was a participant in the FAA Wings Program and was at level 4 or 5 as of March 18, 1998. The mentor held a commercial pilot certificate with airplane single-engine land, airplane multiengine land, and instrument airplane ratings. CAP reported that he had 6,300 hours total time including 3,600 hours in single-engine airplanes. CAP records indicated that the mentor held a CAP aeronautical rating of Command Pilot, and that he had qualified as a mission pilot and mission check pilot. The mentor had most recently satisfactorily completed a CAP annual pilot standardization flight evaluation and mission pilot check pilot evaluation in a Cessna 182 aircraft on April 17, 1999, according to records furnished by CAP. Additionally, according to CAP records, he completed an FAA flight review on September 1, 1998. His most recent mission pilot checkout, according to CAP records, was on July 12, 1997. The record of this checkout indicated that mountainous terrain procedures were evaluated including establishing search altitude, contour search procedures, and canyon search procedures. According to a letter from the FAA Aeromedical Certification Division to the mentor dated May 25, 1999, furnished to the NTSB investigator-in-charge (IIC) by CAP, the mentor had a history of coronary artery disease that required bypass surgery in December 1998. The FAA letter was a response to an application by the mentor for unlimited second-class medical certification on April 13, 1999, and outlined testing and documentation requirements for the FAA's consideration for various classes of special-issuance medical certification. A check of the FAA airman registry on June 18, 1999, gave the status of the mentor's medical certificate application as "pending." AIRCRAFT INFORMATION The aircraft, a 1981 Cessna 182R, had 2,063.5 hours airframe total time, according to CAP's report to the NTSB. CAP reported that the aircraft had undergone an annual inspection on April 12, 1999, approximately 60 flight hours prior to the accident, and a 50-hour inspection on June 6, 1999, approximately 10 flight hours before the accident. According to CAP, the aircraft's Continental O-470-U engine had 1,035.3 hours since major overhaul. The aircraft's estimated gross weight and center of gravity (CG) at the time of the accident was computed to be approximately 2,458 pounds, with an estimated center of gravity of 37.8 inches aft of datum. The gross weight and CG estimate was computed based on the following factors: 1) aircraft basic empty weight at delivery of 1,821.9 pounds and moment of 67,112 inch-pounds (per Cessna delivery documents); 2) pilot and mentor total weight of 396 pounds in pilot seats (weights from FAA airman registry); 3) takeoff fuel of 50 gallons (per statement of another training clinic crewmember who had knowledge of aircraft's fuel state at takeoff on accident flight; see ADDITIONAL INFORMATION section below); 4) estimated fuel burn of 10 gallons from takeoff to accident (1 hour estimated flight time at 10 gallons per hour); and 5) fuel weight 6 pounds per gallon. The aircraft's maximum takeoff gross weight is 3,100 pounds. At a gross weight of 2,458 pounds, the aircraft's forward CG limit is approximately 35.0 inches, and its aft CG limit is approximately 46.0 inches. According to the 1981 Cessna 182R Information Manual, the aircraft's power-off stall speed at gross weight of 3,100 pounds, flaps 10 degrees, and 0 degrees bank angle is 46 knots indicated airspeed (KIAS). According to the manual, this equates to a calibrated airspeed ranging from 52 knots calibrated airspeed (KCAS) at the most rearward CG to 54 KCAS at the most forward CG. The manual indicates that at the same gross weight and flap settings but with 60 degrees of bank, the aircraft's power-off stall speed is 65 KIAS, or a range of approximately 74 KCAS at the most rearward CG to 77 KCAS at the most forward CG. According to a formula found in a U.S. Navy aerodynamics text (H.H. Hurt, Jr., Aerodynamics for Naval Aviators, NAVWEPS 00-80T-80, U.S. Navy, 1960, rev. January 1965), stall true airspeeds at a gross weight of 2,458 pounds are approximately 11% lower than those at a gross weight of 3,100 pounds. (The formula states that the ratio Vs2/Vs1 equals the square root of [W2/W1], where Vs1 and Vs2 are the stall true airspeeds at weights W1 and W2, respectively.) The 1981 Cessna 182R Information Manual states that altitude loss during a stall recovery may be as much as 250 feet. According to the FAA-approved operator's manual for Continental O-470 series aircraft engines, at the engine's maximum rated speed of 2,400 RPM, at a pressure altitude of 5,400 feet and temperature of 36 degrees F (20 degrees C) above standard, an O-470-U engine will attain approximately 22.7 inches Hg manifold pressure and will produce approximately 186 horsepower (HP) (approximately 80.9% of the engine's rated sea-level horsepower of 230 HP.) METEOROLOGICAL INFORMATION A METAR observation taken at La Grande, Oregon (elevation 2,717 feet, approximately 19 nautical miles west of the accident site) at 1735 reported the following conditions: winds from 150 degrees true at 7 knots; visibility 10 statute miles; clear skies; temperature 30 degrees C; dewpoint 3 degrees C; and altimeter 30.02 inches Hg. A remark in the observation indicated a wind shift (from 110 degrees to 150 degrees, based on the previous METAR at 1655) occurred at 1720. Based on the conditions reported in this observation, the La Grande density altitude at 1735 was computed to be approximately 5,000 feet. In its report to the NTSB, the CAP reported that other pilots in the area gave weather conditions at the accident site as a ceiling of 6,600 feet broken with visibility 10 miles or greater, light turbulence, and no precipitation or restrictions to visibility. WRECKAGE The aircraft wreckage was examined at the accident site by investigators from the NTSB, Cessna Aircraft, and Teledyne Continental Motors on July 15, 1999. The accident site was located at the 5,400-foot level in the Chaparral Creek canyon to the east of the generally northwest-flowing Minam River, and was approximately 3 nautical miles east of the Red's Wallowa Horse Ranch private airstrip. Chaparral Creek drains generally southwest, emptying into the Minam River at an elevation of approximately 3,670 feet slightly less than 2 nautical miles from the accident site. Terrain in the Chaparral Creek canyon rises to peak elevations of 5,765 feet approximately 3/4 mile west of the accident site, approximately 7,545 feet slightly less than 1 mile north of the accident site, approximately 7,670 feet slightly less than 1 mile east of the accident site, and 6,613 feet just over 1/2 mile southeast of the accident site. The main wreckage (consisting of the empennage, the inboard section of right wing with inboard aileron section and flap, a burned central section, and the engine and propeller) was located on heavily wooded, sloping terrain that sloped upward in a generally south-to-north direction at a slope angle measured at 18 degrees. A group of trees with freshly broken tops was observed approximately 93 feet down slope from the main wreckage. The magnetic azimuth from this group of broken trees to the main wreckage was measured at 330 degrees magnetic. The vertical angle from the main wreckage up to the tops of this group of trees was measured at 22 to 26 degrees above horizontal. The main wreckage was generally oriented on the same heading as the line from the broken trees to the main wreckage. The outboard sections of both wings, the outboard section of the right aileron, and the right wingtip fairing were found on either side of the line from the group of broken trees to the main wreckage, within a lateral distance of about 33 feet of the line. An area of burned ground approximately 30 feet in diameter extended around the main wreckage, and within the main wreckage, the fuselage from the empennage to the engine firewall and the inboard wing sections were largely destroyed by fire. However, the flaps were observed to be down about 10 to 15 degrees. Most flight instruments were destroyed or unreadable except for the attitude indicator and the directional gyro (DG). The attitude indicator was captured at about 150 degrees left bank and 10 degrees nose low, and the DG indicated about 270 degrees. Additionally, the 10,000-foot pointer of the aircraft's altimeter was observed pointing to approximately 5,900 feet, with the altimeter setting window set to 30.03 inches Hg (the altimeter's 1,000-foot and 100-foot pointers were missing.) The engine, which was fire-damaged, was found in the ground in approximately a 150-degree left bank/10 to 20 degrees nose-low attitude, generally consistent with the indication noted on the attitude indicator. The propeller remained attached to the engine. One propeller blade was bent aft about 5 degrees and was twisted. The other was bent back about 15 degrees at mid-span and then bent forward slightly at the blade tip. Both blades had some degree of leading edge damage and chordwise scratching and/or polishing. The two propeller blades were about 10 to 20 degrees out of opposition with one another. An on-site examination of the engine revealed no evidence of pre-impact engine malfunction. Additionally, a fresh, flat-faced "saw-type" cut was noted through a felled tree of approximately 6 to 8 inches diameter at the accident site. On-site examination of the remnants of the flight control system revealed no evidence of pre-impact failures of that system. FIRE A post-crash fire consumed much of the center portion of the aircraft, from the engine firewall aft to the empennage, along with portions of the inboard wing structure. The post-crash fire also burned or scorched trees and vegetation in the immediate vicinity of the crash site, which is located in a U.S. Forest Service Wilderness Area. During the on-site examination, investigators examined the wreckage for evidence of inflight fire and none was found. MEDICAL AND PATHOLOGICAL INFORMATION Autopsies on both pilots were conducted by the Oregon State Medical Examiner's Office, Portland, Oregon, on June 17, 1999. The cause of the pilot's death was determined to be "blunt impact injuries of head and trunk", and the cause of the mentor's death was determined to be "blunt force injuries." Toxicology testing on the pilot was conducted by the FAA Civil Aeromedical Institute (CAMI), Oklahoma City, Oklahoma. The CAMI toxicology tests screened for legal and illegal drugs and detected the following: 0.362 ug/ml Diphenhydramine in the pilot's heart, and 0.069 ug/ml Diphenhydramine in the pilot's liver. Diphenhydramine is an antihistamine, commonly used in over-the-counter cold and allergy preparations. The CAMI toxicology tests on the pilot did not screen for carbon monoxide, cyanide, or volatiles. Toxicology testing on the mentor was also conducted by CAMI. The CAMI toxicology tests on the mentor screened for legal and illegal drugs, and detected none. The CAMI toxicology tests on the mentor did not screen for carbon monoxide, cyanide, or volatiles. SURVIVAL ASPECTS According to CAP records, when the accident aircraft failed to report back in from its flight by 1805 on June 12, a search was begun. An ALNOT was issued on the missing aircraft at 2017 on June 12, and the Oregon Wing of the CAP opened a search-and-rescue (SAR) mission for the aircraft, mission number 99M-1202A, at 2130 that evening. The search eventually involved aircraft and other resources from the Oregon, Idaho, and Washington Wings of the CAP, as well as helicopters of the Oregon National Guard. The aircraft wreckage was sighted from the air about 1150 on June 14. The CAP then notified the Wallowa County, Oregon, Sheriff's

Probable Cause and Findings

The pilot's failure to maintain aircraft control while maneuvering in a canyon, and the mentor's failure to take adequate remedial action. Factors included box canyon terrain and high density altitude conditions.

 

Source: NTSB Aviation Accident Database

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