[2] He learnt to fly with the London Aeroplane Club at Hatfield with Geoffrey de Havilland, Jr. as his instructor and made his first solo in and passed his A licence in 1934 (flying a DH.60G Gipsy Moth with a Gipsy II 120 hp engine) obtaining a private pilot's licence.
However, his technical and knowledge of aeronautical design at Handley Page made it impossible for him to be deployed on active service[4] although his Ceylonese compatriots in the RAFVR, Rohan Amerasekera (later to command Sri Lankas Airforce), Mickey Dias (later First Law Fellow, Director of Studies and Professor of Jurisprudence at Magdalene College, Cambridge), Rex de Silva, Pilot Officer Ananda Kularatne (son of Sumanadasa's school principal) and Dougald Abayasekera (former cricket captain and head prefect of S. Thomas' College, Mt Lavinia)[5] saw active service.
Sumanadasa worked from 1958 with the Ministry of Education to establish the Institute of Practical Technology at Katubedde, Moratuwa, which opened in 1960.
Sumanadasa was founder principal and was later Head of Civil Engineering at the Ceylon Technical College (CTC).
The Sumanadasa building, named in his honour and built in 1973, remains in use and is one of the largest on the University of Moratuwa site.