Now, Cao has started the second part of his dream to walk along the Belt and Road route. He flew 4,700 kilometers ___69___ Xi’an to Kashgar on Sept. 20, ___70___ (plan) to hike back to Xi’an in five months.

这是2022全国卷2的语法填空题。第69题填 from；第70题填 planning。

请问现在分词短语 planning to hike back to Xi’an in five months 是什么成分？我估计是状语，那是什么状语呢？