August 9, 2010
NTSB Number: AAR-11-03
NTIS Number: PB2011-910403
Adopted May 24, 2011
This accident report discusses the August 9, 2010, accident involving a single-engine, turbine-powered, amphibious float-equipped de Havilland DHC-3T airplane, N455A, which impacted mountainous, tree-covered terrain about 10 nautical miles northeast of Aleknagik, Alaska. The safety issues discussed in this report relate to the lack of a Federal Aviation Administration (FAA) requirement for a crash-resistant flight recorder system, improperly designed or maintained emergency locator transmitter mounting and retention mechanisms, inadequate FAA guidance related to the medical certification of pilots who have had a cerebrovascular event, and the lack of passenger briefings related to survival and communications equipment. Although no weather data deficiencies were found to be related to the accident, the investigation also identified areas in which continued enhancements could further improve aviation safety. Four new safety recommendations concerning these issues are addressed to the FAA, and one new safety recommendation is addessed to the Aircraft Owners and Pilots Association; two safety recommendations to the FAA are reclassified; and two safety recommendations to the FAA are reiterated in this report.
The National Transportation Safety Board determines that the probable cause of this accident was the pilot's temporary unresponsiveness for reasons that could not be established from the available information. Contributing to the investigation's inability to determine exactly what occurred in the final minutes of the flight was the lack of a cockpit recorder system with the ability to capture audio, images, and parametric data.
The National Transportation Safety Board makes the following recommendations to the Federal Aviation Administration:
Consult with appropriate specialists and revise the current internal Federal Aviation Administration guidance on issuance of medical certification subsequent to ischemic stroke or intracerebral hemorrhage to ensure that it is clear and that it includes specific requirements for a neuropsychological evaluation and the appropriate assessment of the risk of recurrence or other adverse consequences subsequent to such events. (A-11-48)
Correct the deficiencies with the in-service automated weather sensor system (AWSS) stations, specifically the known problems with present weather sensors and ceilometers, to ensure that the AWSS stations provide accurate information as soon as practical. (A-11-49)
Implement a collaborative test program in Alaska between the Federal Aviation Administration, the National Weather Service (NWS), the local academic community, and private entities to establish the viability of relaying weather information collected from airborne aircraft equipped with existing data-link technology, such as universal access transceivers, to the NWS Alaska Aviation Weather Unit in real-time. (A-11-50)
If the Federal Aviation Administration's test program recommended in Safety Recommendation A-11-50 establishes that the use of existing data-link technology, such as universal access transceivers, is a viable means of relaying collected information in real-time from an airborne platform, encourage and provide incentives to data link-equipped aircraft operators in Alaska to outfit their aircraft with weather-sensing equipment for real-time data relay. (A-11-51)
The National Transportation Safety Board makes the following recommendation to the Aircraft Owners and Pilots Association:
Educate pilots of 14 Code of Federal Regulations Part 91 flight operations about the benefits of notifying passengers about the location and operation of survival and emergency communication equipment on board their airplanes. (A-11-52)
Previously Issued Recommendations Resulting from this Accident Investigation and Reclassified in this Report
The NTSB issued the following safety recommendations to the Federal Aviation Administration on January 5, 2011:
Require a detailed inspection, during annual inspections, of all emergency locator transmitters installed in general aviation aircraft to ensure that the emergency locator transmitters are mounted and retained in accordance with the manufacturer's specifications. (A-10-169)
The NTSB reclassified Safety Recommendation A-10-169 "Open—Unacceptable Response" in section 2.5.2 of this report.
Determine if the emergency locator transmitter (ELT) mounting requirements and retention tests specified by Technical Standard Order (TSO) C91a and TSO C126 are adequate to assess retention capabilities in ELT designs. Based on the results of this determination, revise, as necessary, TSO requirements to ensure proper retention of ELTs during airplane accidents. (A-10-170)
The NTSB reclassified Safety Recommendation A-10-170 "Open—Acceptable Response" in section 2.5.2 of this report.
Previously Issued Recommendations Reiterated in this Report
The NTSB reiterates Safety Recommendations A-09-10 and -11 to the Federal Aviation Administration, as follows:
Require all existing turbine-powered, nonexperimental, nonrestricted-category aircraft that are not equipped with a cockpit voice recorder and are operating under 14 Code of Federal Regulations Parts 91, 121, or 135 to be retrofitted with a crash-resistant flight recorder system. The crash-resistant flight recorder system should record cockpit audio, a view of the cockpit environment to include as much of the outside view as possible, and parametric data per aircraft and system installation, all to be specified in European Organization for Civil Aviation Equipment document ED-155, "Minimum Operational Performance Specification for Lightweight Flight Recorder Systems," when the document is finalized and issued. (A-09-10)
Require all existing turbine-powered, nonexperimental, nonrestricted-category aircraft that are not equipped with a flight data recorder and are operating under 14 Code of Federal Regulations Parts 91, 121, or 135 to be retrofitted with a crash-resistant flight recorder system. The crash-resistant flight recorder system should record cockpit audio (if a cockpit voice recorder is not installed), a view of the cockpit environment to include as much of the outside view as possible, and parametric data per aircraft and system installation, all to be specified in European Organization for Civil Aviation Equipment document ED-155, "Minimum Operational Performance Specification for Lightweight Flight Recorder Systems," when the document is finalized and issued. (A-09-11)