Fortunately the sky is a big place and a tragedy in the sky did not happen:
BEIJING (Reuters) – China has expressed its “deep concern” to North Korea after a Chinese airplane crossed the path of a rocket launched by the isolated state, China’s foreign ministry said on Friday.
On Thursday, South Korea’s defense ministry said a Chinese civilian plane had “passed as the ballistic missile (from North Korea) was in the course of descending”.
The plane was flying from Tokyo’s Narita airport to the northeastern Chinese city of Shenyang on Tuesday, the ministry said.
“On this issue, we have already contacted the North Korean side to convey our deep concern,” Chinese Foreign Ministry spokesman Qin Gang told a daily news briefing. [Reuters]
You can read more at the link but this is why you close airspace for a missile test to avoid situations like this.