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An Assessment of NASA's National Aviation Operations Monitoring Service (2009) / Chapter Skim
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7 An Assessment of the Utility of NAOMS Data
Pages 39-46

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From page 39...
... 7.1 DATA QuALITY 7.1.1 Anomalies As noted in Chapter 6, NAOMS survey data in the Phase 2 release were not cleaned or modified (unlike those released in Phase 1)
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From page 40...
... 7.1.2 Rounding Another characteristic common in the survey data was the rounding of the responses (raw data) by the respondents (pilots)
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From page 41...
... This type of rounding is common when respondents cannot recall the exact numbers. The committee did not conduct an extensive analysis to assess the magnitude of the rounding bias on the computed event rates.
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From page 42...
... . 7.2 EXTERNAL DATA VALIDATION 7.2.1 Comparisons with Other Data Sources Figure 7.1 One type of external validation involves comparing the attributes of the respondents in the sample to corre R01624 sponding population data from other sources.
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From page 43...
... In addition, the sampling probabilities of flight legs varied with the number of pilots in the aircraft, and these unequal probabilities have to be accounted for when estimating event rates. If there is sufficient information about the precise nature and the magnitude of these biases, it is possible that at least some of them can be accounted for by weighting the responses appropriately.
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From page 44...
... Finding: The intended simple random sampling for the NAOMS study would have facilitated the easy computation of event rates. However, the final sample does not appear to be representative of the target population as indicated by the limited data analysis conducted by the committee.
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From page 45...
... Finding: The committee did not find any evidence that the NAOMS team had developed or documented data analysis plans or conducted preliminary analyses as initial data became available in order to identify early problems and refine the survey methodology. This is consistent with any well-conducted research study.
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From page 46...
...  AN ASSESSMENT OF NASA'S NATIONAL AVIATION OPERATIONS MONITORING SERVICE Recommendation: The publicly available NAOMS data should not be used for generating rates or trends in rates of safety-related events in the National Airspace System. The data could, however, be useful in developing a set of lessons learned from the project.
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Key Terms

  • event rates
  • flight legs
  • hours flown
  • pilots accounted
  • naoms survey

  • event types
  • simple random
  • unredacted data
  • times respondent
  • naoms data

  • event type
  • naoms team
  • flight units
  • sampling probabilities
  • legs flown

  • publicly available
  • confidence intervals
  • experience level
  • naoms study
  • event counts

  • naoms project
  • implausible values
  • anomalous values
  • sample ratio
  • occupied runway

  • pilots reported
  • random sampling
  • population ratio
  • survey results
  • respondent experienced


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