Boeing delivered fewer airplanes in September compared with recent months and past years, as it felt the first effects of the ongoing Machinists strike.

Boeing said on Tuesday it delivered 33 jets in September, down from 40 plane deliveries in August, as a strike mid-month by around 33,000 U.S. West Coast factory workers weighs on output.

Boeing Co. managed to hand over 33 aircraft to customers in September, when a strike shut down large parts of its manufacturing, while warning that the work stoppage at its main production hub in the Seattle area will reduce future deliveries.