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An Assessment of NASA's National Aviation Operations Monitoring Service (2009) / Chapter Skim
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6 The Redacted Data and Their Limitations
Pages 32-38

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From page 32...
... Nevertheless, a number of the conclusions made here, such as those on the limita tions of the redacted data and data quality, will also apply to the survey results from GA pilots. 6.1 PHASE 1 AND 1a REDACTIONS NASA characterized the initial release of data in Phase 1 as "conservative to ensure the responses do not contain confidential commercial information or information that could compromise the anonymity of individual pilots."1 The strategies for redaction included the reordering, generalization, disaggregation, deletion, and/or editing of the survey responses.
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From page 33...
... 2 "Prior to the recent redaction steps taken, NAOMS air carrier survey responses were evaluated by Battelle at two stages. During initial processing, Battelle refined the set of survey responses using a technique called the Chebyshev process and related criteria to remove 322 responses of doubtful quality to avoid contaminating analyses of the responses.
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From page 34...
... This release took a very different form from that of Phase 1; rather than relatively few spreadsheets, this release included more than 100 separate files. The tables included responses that were deleted or separated from Phase 1, such as incomplete survey responses, rare events, and high unique events.
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From page 35...
... • Information for each safety event is given in separate files that cannot be linked. This was done to address the privacy/confidentiality concerns, but it does not allow the user to link information across multiple safety events -- for example, if a single pilot reported multiple event types.
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From page 36...
... as proxies for all of the values in that interval. However, the redacted data provided raw data on the numbers of hours and flight legs flown in a separate file.
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From page 37...
... . It will have no means of tracing a survey response to the individual who provided it; neither FOIA nor discovery actions will pose a confidentiality risk to NAOMS."6 It appears that the NAOMS management team anticipated neither the need to eventually release the survey data to the public nor the consequent problems that would develop.
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From page 38...
... It can comment only on the severe negative impact of the chosen redaction strategy on the data analysis. The issue of preserving the privacy and confidentiality of survey participants is not a new problem.
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Key Terms

  • redacted data
  • event rates
  • legs flown
  • survey responses
  • aviation operations

  • operations monitoring
  • monitoring service
  • national aviation
  • recall period
  • naoms survey

  • survey response
  • event types
  • primary aircraft
  • separate file
  • separate files

  • aircraft type
  • flight hours
  • safety event
  • naoms project
  • hours flown

  • information release
  • air carrier
  • naoms management
  • data provided
  • raw data

  • flight activity
  • carrier survey
  • naoms air
  • management team
  • data quality


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