From Halopedia, the Halo wiki
Very few modifications have been made to the D77C over the existing D77H model, beyond the superficial color scheme and minor chassis alterations. The standard Pelican’s missiles and guns have been completely removed, replaced for civilian use with optical and sensory surveillance systems for the tracking and seizing of fugitives as well as addressing large-scale emergencies. For situations such as natural disasters, terrorist attacks, riots or other strategic integrations which would require a heavily armored vehicle for airborne transportation, nothing comes close in utility to a Pelican.
List of appearances