The company confirmed to the BBC that crew witnessed "what is suspected to be the re-entry" of the missile into the earth's atmosphere.
It added that as things stand no flight routes were being modified.
On 29 November North Korea tested a new intercontinental ballistic missile it said could reach anywhere in the US.
The test-launch raised tension further with South Korea and the US, who on Monday began their largest ever joint air exercise, which the North has branded an "all-out provocation".
'Blew up and fell apart'
