From Halopedia, the Halo wiki
During the Battle of Mombasa in October 2552, numerous F-99 UCAVs were deployed in reconnaissance elements numbering two to three aircraft to the city of New Mombasa, presumably from aircraft carriers a few kilometers off the coast. They provided air support for embattled Marines across the city, particularly the Uplift Nature Reserve. The collective optical feeds provided by drones could also be accessed by ground forces through the UNSC battle network. One of these drones crashed into a statue in front of the Reserve and its ejected optics package was later found by a lone ODST. The Surakan Militia Volunteers had an unknown number of Wombats. In 2558, during the Carrow Conflict, the SMV used an F-99 to spy on the Jiralhanae position, it managed to transmit several images before being shot down.
The F-99 Wombat was originally going to be featured in Halo 3. Though they were omitted from the final game, they were redesigned and featured in Halo 3: ODST. Drones of a different model, which are based directly on the concept art, appear in the background of the multiplayer map Longshore. However, given the depiction of the craft in Longshore as distant background details, it is possible that these are simply meant to be low-detail renderings of the F-99.
Unlike the majority of UNSC air vehicles (which bear the names of birds or other flying animals), the Wombat bears the name of an arboreal marsupial native to Australia.
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