The F.I.R.M. (pronounced the "FIRM") is the name of the intelligence agency which designed and built Airwolf. After Airwolf was recovered and hidden away by Stringfellow Hawke, F.I.R.M. deputy director Michael Coldsmith-Briggs III, codenamed "Archangel" maintained contact with Stringfellow, agreeing to help in the search for his M.I.A. brother Saint John Hawke if Stringfellow will agree to fly Airwolf on F.I.R.M. operations.
The F.I.R.M. maintained a certain ambivalence about this relationship. Whenever the F.I.R.M. sensed an opportunity to seize Airwolf, like in "Moffett's Ghost", it would do its very best to do so. At other times, the F.I.R.M. found it convenient that Airwolf was in autonomous hands and even had to fight off the efforts of other agencies to taka control of the aircraft, like in "To Snare A Wolf".
The Name "F.I.R.M."
The F.I.R.M. is probably a play on the name "The Company" which is a nickname for the C.I.A. The F.I.R.M. is sometimes thought to be a covert branch of the C.I.A. but evidence from various episodes also suggest that it is an independent agency in its own right.
From "Proof Through the Night, it is apparent that the F.I.R.M. is a proper acronym and not just a nickname. The word "F.I.R.M." with periods in between are seen clearly on an official dossier which Marella passed to Hawke. The logo on the dossier also features an eagle's head, reminiscent of the logo of the C.I.A. What the letters of the F.I.R.M. stand are however never mentioned. This is further confirmed later in One Way Express (episode) when Marella shows her ID.
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Location of the F.I.R.M. Headquarters