On March 4, 2008, about 1515 central standard time, a Cessna 500, N113SH, registered to Southwest Orthopedic & Sports Medicine Clinic PC of Oklahoma City, Oklahoma, entered a steep descent and crashed about 2 minutes after takeoff from Wiley Post Airport (PWA) in Oklahoma City. None of the entities associated with the flight claimed to be its operator. The pilot, the second pilot, and the three passengers were killed, and the airplane was destroyed by impact forces and postcrash fire. The flight was operated under 14 Code of Federal Regulations (CFR) Part 91 with an instrument flight rules flight plan filed. Visual meteorological conditions prevailed. The flight originated from the ramp of Interstate Helicopters (a 14 CFR Part 135 on-demand helicopter operator at PWA) and was en route to Mankato Regional Airport, Mankato, Minnesota, carrying company executives who worked for United Engines and United Holdings, LLC.
The National Transportation Safety Board determines that the probable cause of this accident was airplane wing-structure damage sustained during impact with one or more large birds (American white pelicans), which resulted in a loss of control of the airplane.
The safety issues discussed in this report focus on airframe certification standards for bird strikes, inadequate Federal Aviation Administration (FAA) enforcement of wildlife hazard assessment requirements for airports located near wildlife attractants, the lack of published information regarding aircraft operational strategies for pilots to minimize bird-strike damage to aircraft, and inadequate FAA detection of and intervention in improper charter operations. Safety recommendations concerning these issues are addressed to the FAA.
As a result of this investigation, the National Transportation Safety Board makes the following safety recommendations:
To the Federal Aviation Administration:
Revise the bird-strike certification requirements for 14 Code of Federal Regulations Part 25 airplanes so that protection from in-flight impact with birds is consistent across all airframe structures. Consider the most current military and civilian bird-strike database information and trends in bird populations in drafting this revision. (A-09-72)
Verify that all federally obligated general aviation airports that are located near woodlands, water, wetlands, or other wildlife attractants are complying with the requirements to perform wildlife hazard assessments as specified in Federal Aviation Administration Advisory Circular 150/5200-33B, Hazardous Wildlife Attractants On or Near Airports. (A-09-73)
Require aircraft manufacturers to develop aircraft-specific guidance information that will assist pilots in devising precautionary aircraft operational strategies for minimizing the severity of aircraft damage sustained during a bird strike, should one occur, when operating in areas of known bird activity. This guidance information can include, but is not limited to, airspeed charts that depict minimum safe airspeeds for various aircraft gross weights, flap configurations, and power settings; and maximum airspeeds, defined as a function of bird masses, that are based on the aircraft's demonstrated bird-strike energy. (A-09-74)
Require all 14 Code of Federal Regulations (CFR) Part 139 airports and 14 CFR Part 121, Part 135, and Part 91 Subpart K aircraft operators to report all wildlife strikes, including, if possible, species identification, to the Federal Aviation Administration National Wildlife Strike Database. (A-09-75)
Revise 14 Code of Federal Regulations 91.23 truth-in-leasing regulations to include all turbine-powered airplanes. (A-09-76)
Require that Federal Aviation Administration flight plans include a block for the pilot to identify the operator and a block to specify the operating rules under which the flight is being conducted. (A-09-77)
Require 14 Code of Federal Regulations Part 135 on-demand operators to provide their customers with a written document, correspondence, or ticket that expressly describes the terms of carriage, including the regulatory part under which the flight is operated. (A-09-78)
Update and keep current the aircraft charter guide on the Federal Aviation Administration's website to include reliable information on the certification status of on-demand commercial operators and the aircraft that they are authorized to operate. (A-09-79)
Explore and implement strategies to improve on-site inspector surveillance activities at airports and of flight operations to detect and deter improper charter operations. (A-09-80)
Assess why your existing policies, procedures, and practices resulted in a failure to detect the noncompliant actions of Interstate Helicopters and develop additional methods, measures, or procedures for performing inspections of and following up on complaints about 14 Code of Federal Regulations Part 135 on-demand operators that can successfully detect noncompliant charter operations. (A-09-81)
Previously Issued Recommendations Reiterated in This Report
The NTSB reiterates the following safety recommendation to the FAA:
Require all operators of aircraft equipped with a cockpit voice recorder (CVR) to (1) test the functionality of the CVR before the first flight of each day as part of an approved aircraft checklist and (2) perform a periodic maintenance check of the CVR as part of an approved maintenance check of the aircraft. The CVR preflight test should be performed according to procedures provided by the CVR manufacturer and should include listening to the recorded signals on each channel to verify that the audio is being recorded properly, is intelligible, and is free from electrical noise or other interference. The periodic maintenance check of the CVR should include an audio test followed by a download and review of each channel of recorded audio. The downloaded recording should be checked for overall audio quality, CVR functionality, and intelligibility. (A-06-23)