During the First World War most Russian squadrons flew French-designed aircraft, many of them built under licence. Sikorsky's single-seat S-13 and S-14 biplanes were probably not completed. Three two-seat S-16s were built as trainers for bomber crews of the Squadron of Flying Ships in 1915, followed by about twenty-four more as two-seat S-16-2 and single-seat S-16-3 bomber escort and reconnaissance scouts with 80hp Gnome engines in 1916-17. A machine-gun was mounted under the top wing, firing clear of the propeller, until Engineer Lavrov invented an interrupter gear for a fuselage-mounted gun.
For winter operation, a number of S-16s were flown on skis in place of the standard four-wheel landing gear; at least one was fitted with twin floats in 1916. Contemporary accounts show that pilots enjoyed the stability, manoeuvrability and delicate controls of the S-16s, but they were outclassed by German fighters of the time.