Letters that make surface-to-air
s, a, o, e, f, c, r, t, i, u are letters that make 'surface-to-air'
Words within surface-to-air
RF, fa, surf, IR, ACE, face, AC, ace, surface, CE, air, AI, ai, Ur, Sur, Ac, Ce, Ir, Rf are words within 'surface-to-air'