Human error may have been a contributing factor.

人为的失误可能是一个起作用的因素。

《牛津词典》

It was unclear whether human error may have played a role in the accident.

NPR: Investigators Probe Lion Air Crash In Bali

Preliminary investigations suggest some degree of human error or inaction may have made natural accidents worse in some recent cases (above all, in America) turning local problems into bigger ones.

ECONOMIST: Why do the lights keep going out?