You are downbound in an ice filled channel. An icebreaker is meeting you and sounds two short, one prolonged, and two short blasts on the whistle. What action should you take?

Correct Answer: Option D — Stop your headway and await further signals.

Ice navigation whistle signals consisting of two short, one prolonged, and two short blasts direct downbound vessels to stop headway immediately and await further instructions from the icebreaker.