Continuity mistake: Flight scenes and especially dog fights seem to have no continuity at all. Altitude changes from scene to scene between extreme low-level to altitudes above 10,000 ft. and back. Airwolf's weapon bays are open, then closed, etc.
Continuity mistake: Airwolf goes from normal flight to combat mode and back several times per episode when it's supposed to be in passive flight.
Answer: I don't think it's ever explained why Mac refused to tell Hawke where St. John is.