His final transmission at 19 : 39 EST indicated that he was at 5,000 feet ( 1,500 m ) .
The aircraft 's subsequent course is not clear , but the pilot reported ice accumulation and difficulty in gaining altitude .
pilot 's final transmission at 19 : 39 EST indicated that he was at 5,000 feet ( 1,500 m ) .
The aircraft 's subsequent course is not clear , but the pilot reported ice accumulation and difficulty in gaining altitude .