In Arabic, the singular word (سماء) refers to the actual sky, as in (the sky is blue = السمـاء زرقـاء). However, the plural form (*سـمـاوات) usually refers to "the heavens", and thus (سافـر إلـى السماوات) has the same meaning as (passing away), in English.
P.s: There is actually an Iraqi city called (الـسـمـاوة). I don't know the exact context of your source, but there is a chance he might be going to (الـسـمـاوة) instead of going to the heavens, especially if he is planning to come back. Sometimes a small spelling mistake can make the difference between going to Samawah and going to the heavens :)