Journal of Accident Investigation

More documents

Recommendations

Info

DENNIS GROSSI conditions, and circumstances surrounding an occurrence. The introduction of digital recordings also made it practical to use flight recorder data proactively. The introduction of digital avionics and fly-by-wire technologies in the 1980s provided investigators with challenges and opportunities. This new technology eliminated some well-established investigative techniques while offering an opportunity to record and recover vast amounts of previously unattainable information. Indeed, the amount of available information overwhelmed early-model DFDRs. However, the advent of solid-state recorders has solved the recorder capacity problem while improving survivability and reliability. The future of flight recording is promising. Advances in recorder and aircraft systems will allow for the introduction of recording techniques to record video images of the cockpit and data link messages, as well as providing more opportunities for the proactive use of flight data to prevent accidents. THE AUTHOR DENNIS R. GROSSI is a National Resource Specialist for Flight Data Recorders in the Vehicle Recorder Division at the NTSB. Mr. Grossi has served as the U.S. representative to the International Civil Aviation Organization on Flight Recorder Panels. He has also participated in the European Organization for Civil Aviation Equipment, Working Group , “Minimum Operational Performance Specification for Flight Data Recorder System,” and Working Group 0, “On Board Recording of Communications Navigation Surveillance (CNS)/Air Traffic Management (ATM) Messages.” 42 NTSB JOURNAL OF ACCIDENT INVESTIGATION, SPRING 2006; VOLUME 2, ISSUE 1
A Mathematical Cross-Correlation for Time-Alignment of Cockpit Voice Recorder and Flight Data Recorder Data Joseph A. Gregor, National Transportation Safety Board ABSTRACT A new method is described for performing timing correlations between flight data recorder and cockpit voice recorder information. This method involves the use of the crosscorrelation function to “search” the typically larger FDR data file for a best match to the event pattern present in the CVR data file. The results of this search give a first-order estimate of the time differential between identical events as recorded on both units. A simple curve fit may then be employed to obtain a general conversion from time as represented in the CVR, tcvr, and time as represented in the FDR, tfdr. INTRODUCTION Investigators are often called upon to utilize electronic data acquired from multiple sources in the course of the data collection and analysis phase of an accident investigation. The two most common sources of electronic information available in the event of a major aviation accident are the flight data recorder (FDR) and the cockpit voice recorder (CVR) although many other sources of data are present on modern-day aircraft, and these other sources are being utilized with increasing frequency. Currently, most on-board data sources have one negative characteristic in common: they typically operate on an independent time-base. In addition, virtually all recorded data are currently acquired and stored without a time-stamp. As a result, there is usually little or no independent information on the relative or absolute time at which an electronically “recorded” event occurred. All that is known is the relative time between the beginning of each recording, and the time at which the event occurred. A key first step in the accident investigation process is the synchronization of all collected electronic data to a common time-base, followed by a determination of the relationship between this elapsed “ship-time” and an appropriate local or global clock (local time or UTC 1 ). This task is typically accomplished by matching the electronic signature of 1 Coordinated Universal Time - equivalent to mean solar time at the prime meridian (0° longitude). NTSB JOURNAL OF ACCIDENT INVESTIGATION, SPRING 2006; VOLUME 2, ISSUE 1 43
Page 1 and 2: National Transportation Safety Boar
Page 3: OURNAL JOF ACCIDENT INVESTIGATION A
Page 6 and 7: CHARLES H. SIMPSON and controlled r
Page 9 and 10: Investigative Techniques Materials
Page 11 and 12: 24 “I”-shaped stringers that sp
Page 13 and 14: Fractographic Examination Procedure
Page 15 and 16: MATERIALS EXAMINATION OF THE VERTIC
Page 17 and 18: to the left. The left aft lug had d
Page 19 and 20: and forward on the side of the dela
Page 21 and 22: lug in a plane nearly parallel to t
Page 23 and 24: Developing Animations to Support Co
Page 25 and 26: Figure 2, illustrating control inpu
Page 27 and 28: Figure 5. FDR data converted and in
Page 29 and 30: DEVELOPING ANIMATIONS TO SUPPORT CO
Page 31 and 32: Aviation Recorder Overview Dennis R
Page 33 and 34: 2. 3. 4. . 6. On existing transport
Page 35 and 36: As a result of the Swissair acciden
Page 37 and 38: Fire Its obvious disadvantages were
Page 39 and 40: investigators and the recorder indu
Page 41: crew entries to the navigation data
Page 45 and 46: ambiguity, creating difficulty in d
Page 47 and 48: A MATHEMATICAL CROSS-CORRELATION FO
Page 53: of the cross-correlation function t
Page 56 and 57: KRISTIN M. POLAND, LINDA McCRAY, AN
Page 68 and 69: BRUCE G. COURY adult PFD requiremen
Page 70 and 71: BRUCE G. COURY A 6-year observation
Page 72 and 73: BRUCE G. COURY that NASBLA develop
Page 74 and 75: BRUCE G. COURY Finally, the Safety
Page 76 and 77: JANA PRICE AND JIM SOUTHWORTH Notic
Page 78 and 79: JANA PRICE AND JIM SOUTHWORTH NATIO

Journal of Accident Investigation

Create successful ePaper yourself

Delete template?

Save as template?