Yes, CONTRAILS is a Scrabble word!

Letter values in Scrabble US: C 3, O 1, N 1, T 1, R 1, A 1, I 1, L 1, S 1.

Is it a valid word?

CONTRAILS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

an artificial cloud created by an aircraft; caused either by condensation due to the reduction in air pressure above the wing surface or by water vapor in the engine exhaust

Also: condensation trail.