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Navigation Data

Two separate records of flight navigation were collected during the survey.

The first was a continuous American Standard Code for Information Interchange (ASCII) text file from the Precision Lightweight GPS Receiver (PLGR) that recorded only latitudes and longitudes for the entire flight at 30-second intervals. No time values were recorded by the PLGR. The second navigation record was recorded in the subtitles of the video footage that was shot continuously during the survey. Navigation (latitude and longitude), and time (hours, minutes, and seconds in Coordinated Universal Time (UTC)) were continuously imprinted on the video throughout the flight by using a Trimble Centurion GPS. In order to produce a digital record of the navigation that included time, the latitude, longitude, and time were manually extracted from the video every 5 minutes and these values were matched to the latitude and longitude in the PLGR file. By using a custom Perl script, the time values for the remaining navigation fixes were interpolated between the known 5-minute values.

A Nikon MF-14 Data Back used on the Nikon F3 camera marked the date (day of month) and time (hr:min) on the lower right corner of the 35-millimeter (mm) color positives (slide). These values were entered from the photographs into an Excel spreadsheet. It is assumed, for the purposes of location, that the photographs were taken at a constant rate during any given minute of flight. To assign a time value in seconds to each photograph, the number of photographs taken during each minute was evenly distributed across that minute. For example, if 15 photographs were taken during minute 19:00, it was assumed that a picture was taken every 4 seconds. The photographs were then assigned the time values 19:00:00, 19:00:04, 19:00:08, and so on. Additional adjustments may have been made to those positions to compensate for pauses in image collection, for example at inlets and between islands.

Processed Navigation

The processed navigation file can be accessed from within the nav folder or by clicking the following link: ds945_04ach03.csv (CSV file). The file contains 12 fields that are defined as follows:

Field 1: LONGITUDE - estimated longitude (decimal degree, position of aircraft)
Field 2: LATITUDE - estimated latitude (decimal degree, position of aircraft)
Field 3: HR_MIN_SEC - hour_minute_second (UTC)
Field 4: IMAGE - film image filename (year_monthday_r###_s##.jpg, where "r" is the roll number and "s" is the frame number)
            or digital image filename (year_monthday_hhmmssd.jpg, hhmmss denotes hour, minutes, and second of the image)
Field 5: IMAGE_URL - location of the image internal to data series
Field 6: CONTACT_SHEET_URL - location of the contact sheet within the data series
Field 7: YEAR - year the photo was taken
Field 8: MONTH - month the photo was taken
Field 9: DAY - day the photo was taken
Field 10: PRE_POST - type of survey conducted (pre- or post-storm)
Field 11: STORM - (baseline or name of the storm)
Field 12: GEO_AREA - locations surveyed

Raw Navigation

Navigation was extracted from a Rockwell Collins PLGR unit, which recorded a continuous ASCII text file throughout the survey. Locations were recorded at a 30-second interval. No time data were collected. The raw navigation files can be accessed from within the nav folder or by clicking the following link: ds945_04ach03_0917_plgrgov.txt (text file). The file contains 10 fields (separated by a comma) that are defined as follows:

Field 1: NUMBER - sequential number
Field 2: YEAR - year of data collection
Field 3: WAYPOINT NUMBER - waypoint sequential number
Field 4: PROJECTION - "lat_long_dms" (latitude_longitude_DegreesMinutesSeconds)
Field 5: LATITUDE - degrees, minutes, decimal seconds (position of aircraft)
Field 6: LATITUDE - - decimal degrees (position of aircraft)
Field 7: LONGITUDE - degrees, minutes, decimal seconds (position of aircraft)
Field 8: LONGITUDE - decimal degrees (positions of aircraft)
Field 9: ALTITUDE - altitude in feet
Field 10: DATUM - "WGD" (World Geodetic Datum)