ICAO: ICAO flight plan forms may be used for any filing if base operations does not require a signed copy of your flight plan form. If you are departing from or arriving at a military installation, base operations will receive an electronic filing message of your ICAO plan, but not the signed form.
DD-1801: The DD-1801 form is a modified ICAO form with which ForeFlight will send a signed PDF copy of your flight plan to base operations. Enter the base operations email address on the form to accomplish this. Use a DD-1801 when base operations require a signed DoD flight plan form. DD-1801 should only be used when departing from or arriving at a military installation, or as required by base operations from remote fields.
File Electronically: electronic filing, i.e., sending a digital filing messaging through the AFTN network directly to ATC, is optional with the DD-1801 form. Turning electronic filing off will only send the PDF copy to base operations and base operations personnel will need to enter the data to ATC as though they were handed a paper form. This can be used for OPSEC, to delay filing, or to include route elements not understood by the FAA automated system such as MOAs.
What happens to my data? Am I anonymous? The US DoD assumes the liability for its pilots, meaning that no personally identifiable information should be transmitted to the FAA. By default, only information relevant to the aircraft and the route (blocks 1-18 of the ICAO form) are transmitted to the FAA, called the “FPL message.”
In the event of a deviation, accident, or search-and-rescue situation, the FAA may request the search and rescue information and pilot’s information, called the “SPL message.” With ICAO filing, the SPL message may make the pilot personally identifiable. With DD-1801 filing, ForeFlight fully anonymizes the SPL message, and the pilot cannot be personally identified except by base operations.
ForeFlight How-To: Military Flight Bag DD-1801 Filing