Aviation Accident Summaries

Aviation Accident Summary LAX93FA185

TWIN PEAKS, CA, USA

Aircraft #1

N6884P

PIPER PA-24-250

Analysis

NEARING COMPLETION OF HIS FLIGHT ACROSS THE U.S., AND ABOUT 33 MI FROM HIS DESTINATION, THE PILOT DESCENDED AND ENCOUNTERED AN OVERCAST LAYER. UNABLE TO SEE THE UNDERLYING RISING MOUNTAINOUS TERRAIN, AND UNCERTAIN OF HIS EXACT POSITION, THE PILOT REQUESTED ATC ASSISTANCE. HE ADVISED THE CONTROLLER THAT HE HAD A 'HOLE' AND WAS GOING THROUGH IT. THE AIRPLANE WAS RADAR IDENTIFIED. THE CONTROLLER APPROVED THE DESCENT AND ADVISED THE PILOT TO MAINTAIN VFR AT ALL TIMES. IN RESPONSE TO THE PILOT'S INQUIRY 'HOW LOW IS THE TERRAIN UNDER ME RIGHT NOW?', THE CONTROLLER STATED 'THE TERRAIN IS NO FACTOR FOR YOU SIR.' SHORTLY THEREAFTER THE PILOT STATED HE WAS '...LOSING VFR.' THE AIRPLANE IMPACTED MOUNTAINOUS TERRAIN AT 5,550 FT MSL.

Factual Information

SYNOPSIS: On April 23, 1993, at about 1932 Pacific daylight time, a Piper PA-24-250, N6884P, operated by the pilot on a personal flight, descended into instrument meteorological weather conditions and collided with mountainous terrain near the community of Twin Peaks, California. The crash site was also about three miles west of Lake Arrowhead. At the time of the accident, the private pilot was receiving radar services from an FAA controller. The airplane was destroyed by impact forces and ground fire, and the pilot and passenger were fatally injured. The flight originated at an unknown time prior to 1708,* and from an undetermined location either in Arizona, or in a state to its north/east. No flight plan was filed. *All times used in this report are based upon the 24-hour clock and have been converted to Pacific daylight time. HISTORY OF FLIGHT: According to the pilot's brother, days earlier the pilot had departed in the accident airplane from his Northern California home. He flew his airplane to Ocala, Florida, to visit a relative. The accident occurred during the pilot's return flight to California. The brother stated that he resides in Southern California, and during the pilot's return flight he had planned to visit with him. The pilot's intended destination in California was the Brackett Field Airport in La Verne. The brother reported that the pilot had departed from the Ocala Regional Airport in Florida at about noon on April 22. En route to California, the pilot had probably landed several times and may have landed in Texas. The pilot was due to arrive at the Brackett Field on April 23, between 1700 and 1800. The airplane's route of flight was not established over the eastern and mid-continental states. Evidence of the airplane's course was found during a search for its radar track and air-to- ground communications throughout the western states within the FAA's Western-Pacific Region. The search revealed that at about 1708, when the airplane was west of Flagstaff, Arizona, the pilot had requested VFR advisories from the Los Angeles Air Route Traffic Control Center (ARTCC). As the airplane proceeded toward Southern California, the pilot made several additional contacts with air traffic controllers. At 1845, the pilot was informed that he was 31 miles from Daggett, California, and was tracking along a west-southwesterly course. Thereafter, the pilot was directed to change to another radio frequency to continue communicating with controllers at the Los Angeles ARTCC. During the next twenty minutes, the pilot made several contacts with radar controllers. The pilot requested and received information regarding headings to fly and his distance to Pomona. (Pomona is the name of the VORTAC (navigation aid) adjacent to Brackett Field). At 1924:28, the pilot inquired "...Could you tell me how low I could go on the present heading I have?" The controller responded with "...Eight Four Papa right now you're in the minimum IFR altitude I could take you down to is ten thousand six hundred, I can't provide you any terrain advisories below that." Then, at 1924:52, the pilot said "...It's pretty cloudy. I think I can get under em but I'm not sure what the bottoms are." The controller responded with: "Eight Four Papa roger ah I'm not familiar with the terrain out there.... Let me talk to Ontario Approach, we're working on a handoff and they might be able to give you some better help ah getting down. I suggest you maintain your present altitude if you don't have the terrain in sight." At 1925:16, the pilot responded with "Eight Four Papa thanks. I'd appreciate if you could help me." At 1925:30, the controller instructed the pilot to "...contact Ontario Approach...and they should be able to give you a little better terrain advisory." The pilot acknowledged the controller's transmission and contacted the radar controller at the Ontario Terminal Radar Approach Control (TRACON) facility. Seconds prior to the handoff, the Los Angeles ARTCC radar controller had briefed the Ontario TRACON radar controller of the pilot's situation. In part, the ARTCC controller told the Ontario controller that: "Eight Four Papa is having a hard time, says it's real smoggy out there and he can't see anything and he's getting real nervous. We're going to ship him over to you right now...." The Ontario controller acknowledged the briefing. During the remainder of the accident airplane's flight, the pilot only communicated with Ontario TRACON. All communications were provided by the same Ontario TRACON controller. In part, the following communications ensued: TIME* AGENCY EXCERPT OF TRANSMISSIONS** 1927:01 ONTARIO Eight Four Papa Ontario Approach, you're loud and clear sir. 1927:09 PILOT Can you tell me how far I am? It's awful cloudy. I don't know if I can get through the clouds if I go much further. 1927:14 ONTARIO I'll be here to help you sir. 1928:09 PILOT Can you tell how far I am? 1928:12 ONTARIO Eight Four Papa you are exactly three three miles away from Brackett. 1928:20 PILOT Eight Four Papa has a lot of clouds under me. How low can I go where I am right now? 1928:25 ONTARIO Right now you are exactly one two miles north of the Norton Air Force Base. 1928:32 PILOT How low can I go? 1928:35 ONTARIO That depends on you sir, If you can continue a VFR descent, it is at your discretion, advise me if you cannot maintain VFR. 1928:41 PILOT I've got a hole right ahead of me. If I can go on down, I think I can go through it. 1928:46 ONTARIO Maintain VFR at all times sir. Comanche Eight Four Papa proceed as requested. 1929:03 PILOT I've got a hole. I'm going to go through it. 1929:07 ONTARIO That's approved as requested. I will maintain radar contact with you. Maintain VFR at all times. Are you IFR equipped? 1929:16 PILOT Ah yeah, but I can't do it. 1929:18 ONTARIO Okay, understand sir. That's no problem. 1929:23 PILOT How low is the terrain under me right now? 1929:26 ONTARIO The terrain is no factor for you sir. A VFR descent is approved in that area. I will keep an eye on you. 1929:44 ONTARIO If you can continue on a possible heading of one niner zero that will take you to low terrain. 1929:54 PILOT I think I've got my hole. 1929:58 ONTARIO OK. Maintain VFR at all times. Advise me if you do lose VFR. I need to know if you do lose VFR and I'll take you through the terrain. 1930:05 PILOT I think I'm losing VFR. (THIS WAS THE PILOT'S LAST RECORDED VOICE TRANSMISSION.) 1930:07 ONTARIO OK. 1930:44 ONTARIO Comanche Eight Four Papa off your right and approximately two and a half miles it's going to take you down to terrain features of two thousand one hundred feet. (The Controller reported to the Safety Board during the post- crash interview that she had erred in informing the pilot that the lower terrain was to his right; she meant left. The Safety Board also noted that a 3,200-foot MSL elevation contour line existed between the airplane's position and the referenced 2,100- foot MSL terrain.) *The listed transmission times were obtained from Ontario TRACON's transcript. **Punctuation was added by the Safety Board. The complete FAA certified transcript is included in the Board's "Air Traffic Control Group Chairman's Factual Report." Radar track data from the Los Angeles ARTCC indicated that from 1930:36 to 1931:00 the airplane flew along a northwesterly course. Radar data from the Ontario TRACON indicated that from about 1930:51 to about 1931:15, the airplane tracked between westerly and northerly courses. The Los Angeles ARTCC's and the Ontario TRACON's last recorded radar hits on the airplane were at 1931:00, and at about 1931:15, respectively. Both radar facilities indicated that the airplane's last transponder altitude was 6,100 feet. The Los Angeles ARTCC's radar recorded the airplane's last position at 34 degrees, 14 minutes, 39 seconds north latitude, by 117 degrees, 14 minutes, 50 seconds west longitude. The magnetic bearing and distance between this position and the crash site, at about 34 degrees, 14 minutes, 53 seconds north latitude, by 117 degrees, 14 minutes, 43 seconds west longitude, was calculated by the Safety Board as approximately 009 degrees and 0.25 nautical miles. There were no witnesses to the crash. (See the radar track [flight path] charts and the crash site map for a perspective of the airplane's course and proximity to terrain during its last few minutes of recorded flight.) PERSONNEL INFORMATION: PILOT, PIPER COMANCHE N6884P The pilot held a private pilot certificate and was rated to fly single engine land airplanes. The pilot did not possess an instrument rating. No pilot flight record log books were located. The pilot's flying experience listed in this "Factual Report" was approximated from information which the pilot provided to: (1) the FAA on June 12, 1990, and July 6, 1992, applications for Third Class aviation medical certificates; and (2) from Safety Board's estimates which included the flight time to complete the round trip flight across the United States. Regarding the pilot's level of experience flying into the Southern California area, the pilot's brother reported that on several occasions the pilot had flown into the area from the north and via the coastal route from the northwest. However, the brother believed the pilot had never flown into the Southern California basin via the mountainous route from the east, or from an east-northeasterly direction. In summary, the brother stated that regardless of the pilot's flight route approaching La Verne, his level of experience flying into the Southern California basin was minimal. FAA AIR TRAFFIC CONTROLLER, ONTARIO TRACON Based upon information received during interviews and an examination of FAA records, the controller was found to have graduated from the FAA Academy in 1989, and she graduated from the radar training facility in February of 1991. She had no military ATC experience and she was not a pilot. Prior to working at Ontario, she had been a controller at a non-radar tower facility. The controller entered on duty at Ontario in February of 1993. She was certified on the Norton Sector (the airspace sector pertinent to the crash site) and received Full Performance Level status on April 2, 1993. On the day of the accident, she was rested, in good health, and had not taken any medication. The controller reported having familiarity with the general crash site vicinity, having previously flown in a light airplane over the San Bernardino Mountains near Lake Arrowhead. The controller also indicated that she was aware of the proximity of the mountains to the crash site, and acknowledged that the mountainous area was visible (on a clear day) from the TRACON's parking lot. AIRCRAFT INFORMATION: The pilot's brother reported that he believed the pilot had been the sole user of the airplane during the six months which preceded the accident. Prior to that time, the airplane had a co-owner. However, the co-owner had recently terminated his interest in the airplane. The brother stated he believed the airplane's maintenance log books may have been on board the airplane. The brother provided the Safety Board with an invoice showing the airplane had received an annual inspection on May 7, 1992. No engine or airframe times were noted. The owner of the facility which performed the May 7 inspection reported to the Safety Board that prior to the pilot departing for the cross country (accident) flight, the pilot had changed the airplane's oil. No maintenance problems were identified. The airplane appeared to be airworthy. METEOROLOGICAL INFORMATION: The Norton Air Force Base, elevation 1,157 feet mean sea level (MSL), was located about nine nautical miles south-southeast of the accident and was the closest facility which reported aviation weather. About 37 minutes prior to the accident, at 1855, Norton reported, in part, the following weather: Scattered clouds at 6,000 feet above ground level, thin broken clouds at 25,000 feet, visibility seven miles, wind from 220 degrees at six knots, temperature and dew point of 65 and 51 degrees Fahrenheit, respectively, and altimeter 29.87" Hg. About 23 minutes after the accident, at 1955, Norton reported, in part, the following weather: 3,000 scattered, measured ceiling 5,000 broken, 9,000 broken, visibility seven miles, temperature and dew point of 62 and 52 degrees Fahrenheit, respectively, wind from 240 degrees at eight knots, and altimeter 29.89" Hg. At 1927:52, Brackett Field's weather was reported to the pilot as "sky partially obscured measured ceiling three thousand overcast, visibility five, haze, wind two six zero at niner, altimeter two niner eight six. The Brackett Field has an elevation of 1,011 feet MSL. At 1928:20, the pilot reported that he observed "...a lot of clouds under me...." At 1928:41, the pilot reported that he observed "...a hole right ahead of me..." and he stated "if I can go down I think I can go through it." At 1929:03, the pilot reported "...I've got a hole, I'm going to go through it." About 51 seconds later, at 1929:54, the pilot again referred to a hole. He stated, "I think I've got my hole." At 1930:05, the pilot stated, "I think I'm losing VFR." A fireman reported that at about the time of the accident he was located an estimated one-half mile from the crash site. The fireman stated his elevation varied between 5,500 and 6,000 feet MSL. At the time, the sky was not visible, the horizontal visibility was between 200 and 300 feet in fog, the wind was calm, and the temperature was between 42 and 45 degrees Fahrenheit. AIDS TO NAVIGATION: According to the FAA, all electronic aids to navigation pertinent to the airplane's flight, in the vicinity of the crash site, were functional and were operating normally. COMMUNICATION: The air traffic communication tapes were reviewed which contained recordings of the pilot and controller's voices. No evidence was heard of communication difficulties. None of the agencies reported experiencing communicating problems. WRECKAGE AND IMPACT INFORMATION: On April 24, the smoldering wreckage was located in the San Bernardino forest about three-quarters of a mile north-northwest of the community of Twin Peaks, California. From an examination of the accident site and airplane wreckage, the airplane was found to have collided with at least four trees while descending on a southerly course. The main wreckage was found on estimated 10 to 15 degree down sloping mountainous terrain, about 80 yards south of the initial point of impact. The terrain elevation was estimated at 5,550 feet MSL. On the south side of the aforementioned trees at the initial point of impact area (IPI), numerous broken tree limbs, plexiglass fragments and paint chips were observed. (See the Wreckage Diagram.) Score marks in bark, on the north side of tree trunks, were observed an estimated 40 feet above ground level. The airplane's right wing tip and right aileron were observed suspended from tree branches approximately 20 yards south of the IPI. Further south, fragments of the airplane's antiservo tab and left stabilator were found. The left flap was found next to a tree. The flap was observed deformed into a curve shape which matched the curvature of the tree's trunk. The left main landing gear door was found next to another tree, which was a few feet west of the main impact ground crater. The crater was about three feet deep by 10 feet long. Numerous fragments of plexiglass were observed in the crater. The left wing was found a few yards northeast of the crater. One propeller blade was located about 10 feet south of the crater. The blade was observed torsionally twisted and chordwise scratched, and its leading edge was gouged (see photographs). The blade was found secured in the hub assembly and its attachment clamps were intact. Oil-like sludge material was observed in the hub. The second propeller blade was not located. The blade's h

Probable Cause and Findings

THE PILOT'S INADVERTENT FLIGHT INTO IMC, THE RADAR CONTROLLER'S ISSUANCE OF INCORRECT TERRAIN INFORMATION, THE CONTROLLER'S FAILURE TO ISSUE A LOW ALTITUDE SAFETY ALERT, AND THE CONTROLLER'S FAILURE TO PROVIDE EMERGENCY SERVICES.

 

Source: NTSB Aviation Accident Database

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