Several F-99's also appear on nearby aircraft carriers in the multiplayer map Longshore.
The F-99 resembles a now defunct military project named Project Pluto that was an unmanned combat vehicle that could travel at incredible speeds at extremely low levels and deliver weapons such as hydrogen bombs.
The optics package of the F-99 can be seen in the final cutscene of Halo 3: ODST as a "toy" for Vergil
F-99's in Halo are similar to 21st century UAVs.
The F-99 may be inspired from the SR-71 Blackbird.
The F-99 could have been a inspiration to the Sabre in Halo Reach as they both look alike but the Sabre is manned and is a Spacecraft.