—Could you tell me when Mr.Li ------in Huanggang?—Sure.When

—Could you tell me when Mr.Li ______in Huanggang?—Sure.When he arrives,I’ll call you.
应该填will arrive还是arrives呢?据说应该是宾语从句填will arrive…可是为什么呢?感觉这样填、翻译的话问句答语跟情景不符合啊~能不能理解为是时间状语从句填arrives呢?