samwinslow

-- Airspace designation.
data Airspace = A | B | C | D | E | G
  deriving (Eq, Show)

-- The resulting cloud clearance.
data Clearance
  = CC -- Clear of clouds
  | IFR -- IFR only; no clearance required
  | C152 -- 1000 above, 500 below, 2000 horiz
  | F111 -- 1000 above, 1000 below, 1 SM horiz