A Britten Norman BN–2T Turbine Islander aircraft struck the water about 40 metres short of the threshold of runway 12 at Vanimo Airport, PNG, during a landing approach in rain. The aircraft was being operated on a charter flight, and was returning from Wasengla, located about 40 nm southwest of Vanimo. There were five persons on board; one pilot and four passengers. There was no significant impact damage to the airframe or engines. However, the aircraft was substantially damaged due to sea water ingestion in the engines and airframe. AIC comments – The aircraft was certified as being airworthy when dispatched for the flight. – The pilot did not hold a valid PNG Flight Crew Licence, and his Class One Medical Certificate had expired 46 days prior to the accident. – The Operator did not have systems or procedures in place to ensure their pilots met CASA Flight Crew legislated requirements. – The pilot attempted to continue visual flight in extremely marginal visual conditions. – The pilot lost situational awareness and allowed the aircraft to descend into the water on the landing approach. – The pilot had commenced wearing prescription lenses that had photochromic tinting. The intensity of the tinting may not have automatically reversed quickly enough to allow the pilot to adjust his vision acuity to the lower light conditions as the aircraft entered the area of heavy rain.