In the Midlands, North of England, and the USA, all these words are TRAP words.
abbey aft after aghast ant ask askance ass back badge banana banner bask basket Basque bastard batch bath blasphemy blast branch brass cab calf can't cancel cant cask casket cast castle cat chaff chance circumstantial clasp class Cleopatra contrast corral craft daft dance dash demand disaster disastrous drastic draught elastic exasperate expand fancy fast fasten finance flask gas gasp ghastly Glasgow glass graft grant graph grasp grass gymnastic half halve ham hand have Iraq jazz lapse last laugh laughter lax mad man mask masque mass* mast master masturbate math(s) morale nasty panda pass passage past pastoral path plaster plastic raft rafter rag random rant rascal raspberry rather romance sample shaft Shaftesbury shan't slander Slav staff stance substantial Sudan tap task tassel thank transfer transform transit transport vast*mass: traditionally, Catholics have the PALM vowel and Protestants the TRAP vowel.
If you have any questions mail me at peturk@hi.is.