How do I solve 3 across in Daily Telegraph Cryptic 31241?

Question

Accepted Answer

3 across reads "Flying machine triple echo interfered with" (10 letters); the answer is HELICOPTER. It's an anagram clue: the answer is a rearrangement of letters supplied by the clue itself. Look for an indicator like 'mixed', 'broken', 'cooked', or 'wild', and find a phrase whose letters add up to the answer's length. The full step-by-step breakdown is on this page.

Flying machine triple echo interfered with (10)

3A — Flying machine triple echo interfered with (10) — HELICOPTER