Aviation Accident Summaries

Aviation Accident Summary CEN12FA108

Bryan, TX, USA

Aircraft #1

N3590T

PIPER PA-32-260

Analysis

The airplane was on a cross-country flight in level cruise flight about 8,000 feet msl when the pilot flew into an area of heavy rain showers. The pilot informed an air traffic controller that he was diverting around an area of thunderstorms. The pilot last reported that he was in “bad” weather and was going to try to get out of it. Following that transmission, radio and radar contact was lost. A witness on the ground heard a sound resembling an explosion. She reported that at the time she heard the noise the rain was falling as a light drizzle. However, by the time she and her husband got outside to see what the explosion was, the rain started “pouring down.” The witness’s husband found the airplane’s main wreckage about 450 feet southwest of their house. The main wreckage consisted of the entire airplane except for the left wing, vertical stabilizer, rudder, and the right wing tip fuel tank. Those components were located about 200 feet north-northeast of the main wreckage. An examination of the left wing spar showed that the wing failed in positive overload. Flight control continuity was confirmed at the accident site. A postcrash examination of the airplane’s engine and other systems did not reveal any preimpact anomalies. A weather study of conditions in the area at the time of the accident indicated the potential for heavy rain showers, thunderstorms, wind in excess of 45 knots, clear air turbulence, and low-level wind shear. While the pilot’s toxicology testing results were positive for tetrahydrocannabinol carboxylic acid (marijuana) in the liver and kidney, the levels were determined not to be impairing. The pilot had a global positioning system (GPS) unit with a current subscription for Next-Generation Radar (NEXRAD). At the time of the accident the depiction in the cockpit would have reflected weather conditions that occurred a couple of minutes earlier. The GPS unit’s owner’s manual states that NEXRAD weather data should be used for “long-range planning purposes only,” and not to “penetrate hazardous weather,” as the “NEXRAD data is not real-time.” On June 19, 2012, the NTSB issued a Safety Alert to warn pilots using in-cockpit flight information services broadcasts (FIS-B) and satellite weather display systems that the NEXRAD "age indicator" can be misleading. The actual NEXRAD data can be as much as 20 minutes older than the age indication on the display in the cockpit. If misinterpreted, this difference in time can present potentially serious safety hazards to aircraft operating in the vicinity of fast-moving and quickly developing weather systems. In addition to raising pilot awareness on this issue, the Safety Alert also reminds pilots of the importance of obtaining a thorough preflight weather briefing.

Factual Information

HISTORY OF FLIGHT On December 19, 2011, about 2144 Central Standard Time, a Piper PA-32-260, N3590T, impacted terrain following an in-flight breakup near Bryan, Texas. The instrument rated private pilot and four passengers were fatally injured. The airplane sustained substantial damage. The airplane was registered to and operated by the pilot under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Instrument meteorological conditions prevailed and an instrument flight rules (IFR) flight plan was on file. The cross-country flight had originated from the Clayton County Airport (4A7), Hampton, Georgia, approximately 1345. After a planed fuel stop at the Jackson-Evers International Airport (JAN), Jackson, Mississippi, the flight departed about 1750 for the TSTC Waco Airport (CNW), Waco, Texas. At 2119, the pilot contacted Houston Intercontinental Terminal Radar Approach Control (TRACON) and reported he was “level at eight thousand [feet mean sea level]”. The controller for Houston TRACON acknowledged and told the pilot that his present heading was good for about 40 miles, at which he should make a right turn “towards t-s-t-c (CNW).” The pilot responded, “Okay … I was looking at my nexrad, is up ahead … [and considering] taking about a two-five-zero heading for a little while, that be all right?” The controller told the pilot, “that two-fifty will put you in some moderate to heavy precip … from what I am showing right now”. The controller then said, “… you’re looking good right now till about twenty miles north of College [Station] then you can start bending it to the right, there is some pretty good gaps in the weather once you get around that area.” The pilot acknowledged. At 2132, the controller told the pilot, “I am showing you’re skirting right along the edge of a uh light to moderate precipitation area”. The pilot responded that he was seeing the same thing and maneuvering south to find a “hole” to go through. At 2133, the controller told the pilot, “I do have a uh heavy to extreme cell at your one to two o’clock and about eight miles, um looks like once you get on the back side of that uh you can make a right turn toward uh t-s-t-c that will be pretty good.” The pilot acknowledged and said, “… if it’s all right with you we will hold this heading right here until we get south of that.” The controller said that was alright. At 2137, the controller inquired if the pilot was “getting any lightning” off of his right side. The pilot said no, but that he was going to make a left 15-degree turn for about two to three minutes. The controller said that was fine and “as you are able you can turn right direct to uh t-s-t-c.” The pilot then said that he was showing a “pretty good storm” to his right and were about to be past it, after which he would make a right turn direct to CNW. At 2142, the controller told the pilot that he was showing “pretty heavy weather” southeast of CNW that appeared to be moving northeast. The controller then contacted the pilot and said, “It looks like you just made a left three-sixty on me; what’s going on?” Then the controller said, “November nine zero tango, I show you headed right into heavy weather, now uh I would suggest you turn back right to about a two-two-zero heading.” The pilot responded, “Okay, yea, we’re turning right. We’re in some bad weather here. I’m going to try to get out of it.” That was the last radio transmission the pilot made. A review of radar track data showed the airplane traveling on a west-southwest heading of about 230 degrees and an altitude of 8,000 feet mean sea level (msl). At 2137, the airplane turned south to a heading of 193 degrees. Two minutes later, the airplane turned back to a southwesterly heading. Then at 2142, the airplane made a right turn toward the northeast and began descending at a rate of about 600 feet per minute. The descent continued until radar contact was lost at 2144. At that time, the airplane was at 6,800 feet, descending at a rate of 840 feet per minute, and on a heading of 315 degrees. The airplane’s position was 18 nautical miles northeast of College Station, Texas. About 2150 an ear witness, located in her house, heard a sound resembling an explosion. The witness reported that at the time she heard the noise, the rain was falling as a light drizzle. However, by the time she and her husband got outside to see what the explosion was, the rain started pouring down. The witness’s husband located the main airplane wreckage approximately 450 feet southwest of their house. PERSONNEL INFORMATION The pilot, age 33, held a private pilot certificate with a single-engine land and instrument airplane ratings. A review of the pilot’s logbook showed he had successfully completed an instrument check ride on September 13, 2009. Further review of the pilot’s logbook showed he had 392 total flying hours, with 347 hours as pilot-in-command, and 378 hours being in the airplane make and model. The pilot had recorded 14 hours of actual instrument time, and 40 hours simulated instrument time. The logbook also showed the pilot had flown 46 hours in the 90 days prior to the accident, 15 hours in the 30 days prior to the accident, and two hours in the previous 24 hours up to the accident. The pilot held a current Third Class medical certificate with no limitations or waivers, dated January 28, 2010. AIRCRAFT INFORMATION The airplane was a 1966 Piper Aircraft, model PA-32-260, serial number 32-336. The airplane was powered by a Lycoming model O-540-E4B5 carbureted engine rated at 260 horsepower at 2,700 rpm. The airplane was registered to the pilot and another individual on March 22, 2011. A review of the airplane logbooks showed the airplane underwent an annual inspection on February 8, 2011. The total airframe time recorded at the annual was 6,125.0 hours. The last recorded maintenance actions performed on the airplane was an altimeter certification, static leak check, transponder certification, and altitude reporting test on September 12, 2011. The airframe time at the test was 6,327.8 hours. METEOROLOGICAL INFORMATION The National Transportation Safety Board’s Meteorologist gathered all relevant weather data from the National Oceanic and Atmospheric Administration (NOAA) National Weather Service (NWS) sources including the National Climatic Data Center (NCDC). The NWS Surface Analysis Chart for 2100 CST depicted an outflow boundary just northwest of the accident site stretching northeastward from the accident site into northeast Texas. A low pressure system was located in the Texas Panhandle with an occluded front stretching northeastward into Oklahoma before becoming a stationary front and stretching southward through central Texas. The station models north and west of the accident site depicted temperatures in the mid 50’s and 60’s [degrees] Fahrenheit (F), with temperature-dew point spreads of 3 degrees or less, a variable wind at 5 knots, cloudy skies, and light rain. Station models to the south and east of the accident site had temperatures in the low 60’s to low 70’s F, temperature-dew point spreads of 5 degrees F or less, a south to southeast wind of 5 to 15 knots and cloudy skies with moderate rain. The accident site was located in a region of relatively flat terrain with warm moist air located throughout eastern Texas. With an outflow boundary, and its ability to be a lifting mechanism and lift the warm moist air located near the accident site, thunderstorms, rain showers, and associated turbulence would be expected near the accident site at the time of the accident. The NWS Storm Prediction Center Constant Pressure Charts for 1800 CST depicted a mid-level trough, an elongated area of low atmospheric pressure, southwest of the accident site, which acted as a lifting mechanism to help in the formation of clouds, showers, and thunderstorms in central, northern, and eastern Texas. The closest weather reporting station to the accident site was an Automated Weather Observing System (AWOS) located at Hearne Municipal Airport (KLHB), 19 miles west-southwest of the accident site. At 2135, the weather was wind calm, 5 miles visibility and light rain, a broken ceiling at 2,700 feet agl, overcast skies at 3,400 feet, temperature 16 degrees Celsius (C), dew point temperature 15 degrees C, an altimeter setting of 29.88 inches of mercury, and remarks: automated weather observation station with a precipitation discriminator, one-hourly precipitation of 0.19 inches. At 2155, the weather at KLHB was wind calm, 10 miles visibility, a broken ceiling at 2,700 feet agl, overcast skies at 3,200 feet, temperature 16 degrees C, dew point temperature 15 degrees C, an altimeter setting of 29.88 inches of mercury, and remarks: automated weather observation station with a precipitation discriminator, lightning distant northeast, one-hourly precipitation of 0.33 inches. The closest upper air sounding to the accident site was from Fort Worth, Texas (KFWD) site number 72249, located about 123 miles northwest of the accident site. At 1800 CST, the sounding depicted a conditionally unstable vertical environment with the Lifted Condensation Level (LCL), the height at which a parcel of moist air becomes saturated when it is lifted dry adiabatically, at 726 feet msl, and a Convective Condensation Level (CCL), the level in the atmosphere to which an air parcel if heated from below will rise adiabatically without becoming colder than its environment just before the parcel becomes saturated, of 8,892 feet. The sounding had a relative humidity of 80 percent or more from the surface to 1,500 feet, and again from 4,500 feet to 13,000 feet. The freezing level was identified at 11,414 feet. The precipitable water value was 1.13 inches. The KFWD sounding indicated a moist conditionally unstable environment considered favorable for the development of clouds and precipitation from the surface through 14,000 feet. The potential for clouds was indicated by Rawinsonde Observation (RAOB) between the surface and 1,500 feet, then again from 4,500 feet through 14,000 feet. Icing conditions were indicated by RAOB about 13,000 feet. The sounding wind profile indicated a surface wind from 275 degrees at 3 knots that increased to 40 knots by 4,000 feet with the wind out of the southwest. The wind backed to the south from 4,000 feet through 14,000 feet while increasing in speed to 60 knots. Low-level wind shear (LLWS) was identified by RAOB between the surface and 2,000 feet. RAOB detected the potential for clear air turbulence in several layers between the surface and 14,000 feet. A computer model generated upper air sounding created for the accident site for 2100 CST depicted a conditionally unstable vertical environment with the LCL at 703 feet, a CCL of 2,089 feet, and a Level of Free Convection, the level at which a parcel of saturated air becomes warmer than the surrounding air and begins to rise freely, at 3,511 feet. The sounding had a relative humidity of 80 percent or more from the surface to 8,000 feet. The freezing level was identified at 11,662 feet. The precipitable water value was 1.38 inches. The model sounding indicated a moist conditionally unstable environment, which would have been supportive of cloud formation, rain showers, and thunderstorms. The maximum vertical velocity possible with rain showers and thunderstorm updrafts was 33 meters per second or 64 knots given the model sounding environment. The potential for clouds was indicated by RAOB between 1,000 feet and 10,000 feet. No icing conditions were indicated by RAOB below 14,000 feet. The model sounding wind profile indicated a surface wind from 149 degrees at 9 knots that increased to 50 knots by 4,000 feet with the wind veering to the southwest. The wind remained at 45 knots while out of the southwest through 14,000 feet. LLWS was identified by RAOB between the surface and 2,500 feet. RAOB detected the potential for clear air turbulence between the surface and 10,000 feet. Infrared data from the Geostationary Operational Environmental Satellite number 13 (GOES-13), from 2140 to 2202 CST, showed a narrow enhanced band of clouds that moved eastward over the accident site. The GOES-13 brightness temperature over the accident site at 2145 was minus 8 degrees C, which when considering the 2100 CST model sounding indicated cloud top heights of about 16,000 feet. The closest NWS Weather Surveillance Radar-1988, Doppler (WRS-88D) was in Granger, Texas (KGRK), about 60 miles west-southwest of the accident site. The WSR-88D operates in several scanning modes identified as Mode A and Mode B. Mode A is the precipitation scan and has two common scanning strategies, the most common of which is where the radar makes 14 elevation scans from 0.5 degrees to 19.5 degrees every four minutes. This scanning strategy is documented as column coverage pattern 12 (VCP-12). Mode B is the clear-air mode where the radar makes 5 elevation scans during a 10 minute period. At the time of the accident the Granger WSR-88D was operating in the normal precipitation mode (Mode A, VCP-12). The base range reflectivity image for 2136 CST depicted a line of strong to intense echoes west of the accident site corresponding to a line of heavy rain showers. A new area of echoes was seen southwest of the accident site on two of the elevations scans, 0.9 degrees and 1.4 degrees. This new area of echoes intensified forming along the south side of the line of rain showers. At 2145, elevation scans at 0.5 degrees, 0.9 degrees and 1.4 degrees showed the strong to intense echoes continue to move northwestward and over the accident site. Airplane radar track data obtained from Air Traffic Control overlaid on the base reflectivity at 2136 CST showed the airplane flying southwest with very strong echoes just west of the airplane’s flight path. About 2141 CST the airplane had entered light echoes with strong to very strong echoes located just to the southwest of the airplane and along the airplane’s flight direction. At 2145 CST the base reflectivity at 0.9 degrees showed very strong to intense echoes above the last part of the airplane’s recorded track and over the accident site. These very strong to intense echoes were indicative of a strong rain shower. Two SIGMETS were valid for the area west of the accident site at the accident time. Convective SIGMET 5C and Convective SIGMET 7C advised of a line of storms moving from 200 degrees at 45 knots with embedded severe thunderstorms. Thunderstorm tops were forecast above Flight Level 450 with wind gusts to 50 knots possible. No AIRMETS were active for the accident site at the accident time. For additional information, see National Transportation Safety Board, Weather Study, CEN12FA108 in the NTSB Docket Management System. WRECKAGE AND IMPACT INFORMATION The airplane came down in a pasture field approximately 20 miles north-northeast of Bryan, Texas on a 018-degree magnetic heading. The airplane wreckage came to rest spread over an area approximately 1/2 mile long by 200 feet wide. The debris path followed an approximate heading of 210 degrees. The main wreckage was located at 30 degrees, 56.844 minutes North latitude and 096 degrees, 16.124 minutes West longitude. It was resting nearly inverted against several small trees. The main wreckage consisted of the airplane cabin and fuselage, right wing, right main landing gear, the vertical stabilator and elevator, the nose gear, engine, engine cowling, and propeller. The fuselage, cabin and engine were oriented on a 220 degree heading. The engine and propeller were partially buried in the ground so that only the right side and top of the engine could be seen. The upper cowling was broke and rested on top of the engine. The propeller blades were partially exposed. The blades showed torsional bending and chordwise scratches. The propeller spinner was crushed inward on one side. The airplane’s nose gear was broken aft and to the right. The airplane’s cabin was crushed inward and aft. The windscreen was broken out and the frame was bent inward. The cabin door was

Probable Cause and Findings

The pilot’s inadvertent encounter with severe weather, which resulted in the airplane’s left wing failing in positive overload. Contributing to the accident was the pilot’s reliance on outdated weather information that he received on his in-cockpit Next-Generation Radar (NEXRAD).

 

Source: NTSB Aviation Accident Database

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