Army Helicopter Also Sounds Like a US Coastal Wind
Puzzle 12 of Running a Marathon Pack
Question is: Army Helicopter Also Sounds Like a US Coastal Wind
and the answer is: CHINOOK
Word Meaning:
CHINOOK — (Canada, US, physics, meteorology) The descending, warm, dry wind on the eastern side of the Rocky Mountains that generally blows from the southwest and can rapidly increase the temperature due to the much warmer air it brings.
Definitions from Wiktionary.