This program decodes the raw Flight Data Recorder (FDR commonly called "black box") file for United Airlines Flight 93 (UAL93) included by the US National Transport Safety Board (NTSB) on CDROMs provided in response to FOIA (Freedom of Information Act) requests for information regarding the events of September 11th 2001.

The program allows you to selectively decode parts of the FDR file and generate a Comma Separated Value (CSV) file containing the selected information. The first line of the CSV file contains the parameter names and it can be opened by various programs including Microsoft Excel and Microsoft Access.

Although the NTSB provided CSV files generated from the FDR file which were also included on the CDROMs, I have created this program so that parameters can be selectively included in the CSV files resulting in files with fewer columns and also to decode some information not included in the NTSB CSV files.

As I am providing this program free of charge, it is provided as is.

I take no responsibility for what the program does or doesn't do.

However, you can email feedback to me (Warren Stutt).

You will need to download a copy of the FDR file ual93.dlu. You can download a copy from here. You can also get an ISO image of the entire CDROM that I received in response to my FOIA request which includes the FDR file from here.

Click on the button to choose the location of the FDR file.

Each subframe appears on a separate line in the output file. Subframes are recorded in the FDR once per second.

Put a tick in the Include Incomplete Subframes check box if you want to also include incomplete subframes in the output. Incomplete subframes will most likely have some valid information and some invalid information. The invalid information will likely consist of unusual values. If you do choose to include the incomplete subframes, you will probably want to mark "Incomplete Subframe" as one of the included parameters in your output file (More on this below). This will let you know which lines may contain invalid information.

Put a tick in the Split Output File in to files containing no more than 30000 rows check box if you want the output file split up in to files that can be more easily worked with in Microsoft Excel. The first 30000 rows will have the file name chosen in the CSV File To Be Generated dialog box mentioned below. The second 30000 rows will have the same file name but with the number 2 inserted before the last full stop in the file name. The third 30000 rows will have the number 3 inserted in the file name and so on. The last file name will have the remaining rows. The first line of each output file will contain the parameter names.

Put a tick in the Maximum One Line Per Subframe check box if you want only one line to be output for each subframe. This is the default option. If the check box is cleared more than one line will be output per subframe for the acceleration and some other parameters since there are several values for these parameters recorded in each subframe. If the check box is ticked, only the first line will be output for each subframe.

The first time the program is started; all the parameters are listed in the Excluded Parameters list box. Only the parameters listed in the Included Parameters list box are included in the output file. I have grouped some of the parameters that have similar names together so each entry in the Included Parameters list box can create more than one column in the output file.

To move parameters form the Excluded Parameters list box to the Included Parameters list box, first select a parameter by clicking on it. You can select more than one parameter by holding down the SHIFT or CTRL keys while clicking on the parameters. Then click on the button to move the parameters you selected across. You can move all the parameters across at once by using the button.

Similarly parameters can be moved back from the Included Parameters list box to the Excluded Parameters list box by using the and buttons.

Once you have selected the parameters you want included, click on the button to choose where you want the output file to be saved and to generate the file. All the program options will be disabled (greyed out) until the file has been completely generated. Close the Output Progress dialog box if you want to cancel generating the output file.

When you exit the program, the options you selected will be saved in the file UAL93FDRDecoder.config.xml in the same folder as the program and reloaded next time you start the program.

The output of the program closely matches the NTSB CSV files for the parameters and periods of time that the NTSB CSV files cover. For further information see Notes on Parameters for the UAL93 FDR Decoder.

Go back to the UAL93 FDR Decoder page.