The NTSB has called the FAA’s response “unacceptable” to four out of six safety recommendations addressing human fatigue and duty-time limitations. The agency issued the report to coincide with National Sleep Awareness Week. “The Safety Board is very concerned about reducing accidents and incidents caused by human fatigue,” NTSB chairman Mark Rosenker said, adding that fatigue was a probable cause or contributing factor in “numerous” accidents. The recommendations include requiring training, check flights, ferry and repositioning flights to be included in a pilot’s total revenue time; ensuring that flight and duty time limitations take into consideration research findings in fatigue and sleep issues; reviewing the issue of personnel fatigue in aviation maintenance; and taking into consideration the length of a duty day, starting time and workload when assigning flight crew hours. The FAA has not to date altered a 2001 Federal Register notice that calls for eight hours of rest in any 24-hour period that includes flight time. An FAA spokesman told AIN, “We believe the rules and guidance we have in place are fundamentally sound.”