4 KudoZ points awarded for this answer. Comment: "This was a TRICKY one! Kevin, how interesting that you should use the phrase "en route". The ONLY way this phrase "makes sense" is if the Chinese "航路" is a direct translation of "en route," because 航路 normally means "flight path" or something similar. Based on the sentence + your interpretation, I am fairly confident it does indeed refer to "in-flight" inspection... Thanks to all!"