North Korean airspace could be declared a no-fly zone in response to the country's missile tests, the aviation industry's global trade body says, after the latest launch came within sight of a passenger plane.
Excluding aircraft from the area is one option open to aviation safety regulators as they ponder how to deal with the arbitrary firing of missiles that has encroached on busy commercial air routes between Asia and North America.
Pilots on a plane operated by Hong Kong carrier Cathay Pacific Airways saw from a distance what were believed to be the remnants of a North Korean rocket fired last Wednesday. The airline disclosed the sighting on Monday in an internal note to staff.
While no international flights currently use North Korean airspace, the area around it is full of activity. Any sanctions by the United Nations safety regulator, the International Civil Aviation Organisation (ICAO), would likely bring into sharper focus the safety of aircraft operating nearby as well as commercial flights in and out of North Korea.
"The ICAO could declare a no-fly zone," Alexandre de Juniac, director general of the International Air Transport Association (IATA), said at its Geneva headquarters on Tuesday. "We are working with the ICAO on how we can protect these zones [for] flying.
"The ICAO is trying to implement and ask North Korea to apply safety rules. If you look at the North Korean airspace, there are not too many aircraft overflying."
An IATA spokesman said there was an obligation on North Korea to provide notice of any missile tests, which thus far had not been given. In the absence of such notice, it was up to airlines to carry out risk assessments to see how far from North Korea it would be safe to fly.
"For sure" there was no risk to passengers and airlines, de Juniac said.
Carriers decide on their own flight paths based on safety notices from local and international agencies.
Cathay Pacific said on Monday that despite the missile sighting it would not change its routes.
Airlines have not yet taken any action in light of the North Korean rocket launches. In 2015, when Russia escalated its military campaign against Islamist militants in Syria, it started firing rockets from the Caspian Sea, which prompted international aviation safety agencies to issue warnings.
The alerts spurred airlines to eventually take action based on their own risk assessments. However, not all carriers steered clear of "at-risk" routes identified at the time.
In Monday's message on an online staff communication platform, Cathay's general manager of operations, Mark Hoey, said: "Today the crew of CX893 reported: ‘Be advised, we witnessed the DPRK missile blow up and fall apart near our current location. We advised ATC [air traffic control] and ops [operations] normal. Just letting you know.' Looking at the actual plots, CX096 might have been the closest, at a few hundred miles laterally."
Other aircraft were also in the area at the time, according to radar information. Taiwanese carrier China Airlines' flight from Vancouver and an Eva Air flight from Seattle, both headed to Taipei, and Japan's All Nippon Airways' Frankfurt flight from Tokyo were all over the area where the rogue state's missile terminated.
Some European airlines adjusted flight routes in response to Pyongyang's earlier missile tests this year. Lufthansa said it had changed course, without specifying details. Air France said it had widened its no-fly zone around North Korea.
The stretch of airspace hugging Japan's east coast over the Pacific Ocean is a prime route used by hundreds of flights every day criss-crossing Asia and North America. Another important route directs planes over northern China and into Russia.