NTSB Identification: ERA12FA566
14 CFR Part 91: General Aviation
Accident occurred Monday, September 17, 2012 in Crane Hill, AL
Probable Cause Approval Date: 11/17/2014
Aircraft: MOONEY M20M, registration: N1085A
Injuries: 2 Fatal.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
The pilot initially delayed the cross-country flight for convective weather, but later took off, encountered weather in a climb, and advised an air traffic controller that he was looking at “ADS-B” (Automatic Dependent Surveillance-Broadcast). As the flight progressed, the airplane climbed to 13,000 feet, and the pilot asked the next controller if there were any reports of icing ahead about 15,000 feet. The controller noted no reports of icing, “but quite a bit of deviation, quite a bit of clouds and precipitation in front of you.” The pilot requested 15,000 feet “to see if I can see things better,” which was approved by the controller. Upon switching to the next controller, the pilot was advised of moderate to extreme precipitation for the next 90 miles. The pilot then stated that in looking at the ADS-B, he needed to deviate. Deviation was approved, and, 2 minutes later, the pilot advised the controller that he was making another deviation, which the controller acknowledged. Eighteen minutes after that, the controller told the pilot to change radio frequency, and the pilot responded, “unable, we’re battling some pretty bad...”. The airplane subsequently made numerous turns and altitude excursions, turning 90 degrees to the right and descending to 14,600 feet, then turning another 90 degrees right and descending to 14,100 feet. After making a sharp left turn, the airplane climbed to 15,500 feet, then made another sharp left turn, and, as it began a final rapid descent to the ground, the pilot issued several mayday calls. An examination of the wreckage revealed no mechanical anomalies that would have precluded normal operation.The expected ADS-B cockpit depiction compared to real-time, ground-based radar indicated significant differences in the depiction of hazardous reflectivity (rain). In the ADS-B product, the airplane was depicted as being clear of moderate or heavy rain as it made its final various turns. However, rea-time radar imagery indicated that the airplane would have been in or near moderate-to-heavy rain.The pilot indicated to the controller that he was using ADS-B in a tactical manner; however, ADS-B is intended to be used in a strategic manner . It is unknown why the pilot lost control of the airplane in moderate-to-heavy rain; he may have become confused and lost situational awareness when turning into what he thought were clearer conditions per the ADS-B depiction but was actually worse weather. ADS-B does not show what the weather is; it shows what the weather was up to 15 to 20 minutes earlier.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot’s loss of control in moderate-to-heavy rain. Contributing to the accident was the pilot’s reliance on ADS-B for tactical weather avoidance.
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