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5 Analysis of NAOMS Questionnaires
Pages 23-31

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From page 23...
... These questions were designed to be asked routinely over a long period of time to enable the computation of safety event rates and event rate trends. To select the topics in Section B, the NAOMS team first consulted "existing aviation safety data repositories maintained by NASA, the FAA, and the NTSB to identify known safety issues." The team also asked pilots and others in the aviation field about "safety issues important to them based on their first-hand operating experience." 1 This collection of information occurred through consultation with the ASRS analysts, AC pilot focus-group sessions, and two workshops hosted by the NAOMS team.
From page 24...
... Three different Section C question sets were developed for the AC questionnaire: one concerning minimum equipment lists, a second one addressing in-close approach changes, and the final one requested by a Commercial Aviation Safety Team subgroup of the Joint Implementation Measurement Data Analysis Team (CAST-JIMDAT) focusing on "the development of baseline aviation system performance measures."5 • Section D -- Questionnaire FeedbackThe questions in Section D provided respondents with a chance to give feedback regarding their survey experience to the interviewers who called.
From page 25...
... , also includes nonscheduled air taxi operators providing service in some very small aircraft in some very challenging operating environments (such as Alaska) as well as charter-flight operators and small, nonscheduled cargo aircraft operators.
From page 26...
... For example, during the 1989 through 2008 period, Part 121 scheduled airline flight hours increased 77 percent, while Part 135 flight hours decreased 25 percent and general aviation11 flight hours declined 21 percent.12 Thus the inability to link the safety-related event either to the aircraft type or to the type of operating environment would seem to severely hinder, or more likely prevent, any meaningful analysis of event rates by aircraft type or type of operation. Moreover, because the mix of operations included in the NAOMS aggregate rates is likely to change over time, trends in the NAOMS aggregate rates would not necessarily reflect trends in the occurrence of these events in the airspace system.
From page 27...
... Finding: Both the air carrier and the general aviation questionnaires asked respondents to include events, flight hours, and flight legs in segments of aviation that went beyond even the broadest definition of AC operations and beyond the conventional definition of gA. As a result, highly disparate segments of the aviation industry were aggregated into the safety-related event rates that were calculated from these surveys.
From page 28...
... One question asks about uncommanded movements of control surfaces, but the pilot would not necessarily know what failure resulted in what appeared to be an uncommanded movement. Another question asks for how many degrees an aircraft rolled in a wake turbulence encounter, but without a post-flight analysis of the flight data recorder, a pilot would not know how much the aircraft had rolled.
From page 29...
... This question includes several conditions -- time period, evasive action, imminent collision, 500 feet -- that the respondent must keep in mind while deciding on an answer. Doing so is particularly difficult in a telephone interview.
From page 30...
... The problematic types of questions exemplified above must be carefully examined using cognitive testing techniques,19 and the committee did not see any evidence that this had been done. It is possible that some of these questions could not be worded more precisely, in which case they should not have been included in the survey.
From page 31...
...  ANALYSIS OF NAOMS QUESTIONNAIRES part of "safety-related events," some respondents might deduce that there is something inherently unsafe about an approach change inside of 10 miles if the crew did not request it. The response to this question and whether or not there was a potential safety concern could vary greatly, depending on where the change was initiated and on how much of a heading change would be required in the maneuver.


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