HE torpedoes versus airplanes?

The rulebook says HE torpedoes “can hit multiple ships.” What about planes? Are they immune? If not, what’s the process for the torpedo attacking them?

Follow-up question: How do HE torpedoes interact with Chaff? A strict RAW reading says that chaff can block an HE’s attack, and since the chaff rules state that a successful roll destroys the torpedo, this blocks the HE’s entire attack, not just against the chaff-carrying ship.

My internal sense of logic says this should not be the case, so I’m asking here.