He was posted to No. 32 Squadron RFC to fly the Airco DH.5 single-seat fighter, and scored five victories (four shared) between 30 October and 5 December 1917. In early 1918 Tyrrell's squadron was re-equipped with the S.E.5a fighter. On 21 March the Germans launched their Spring Offensive on the Somme Front, and on 7 April Tyrrell claimed three enemy fighters shot down over Lamotte. On 10 April No. 32 Squadron RAF was assigned to operations further north over the Lys Front, where Tyrrell gained two more victories, on 11 and 12 April.