North Korea's accelerated missile testing may pose a risk to passenger jets in the area, officials fear, as Pyongyang does not regularly give notice of its plans as required under international agreements.

Recently North Korea tested an intercontinental ballistic missile that it says is capable of hitting the continental United States.

But the missile may have posed a more immediate threat, flying within miles of the flight path that a passenger jet had just completed.

The missile came down 150 kilometres (93 miles) northwest of Okushiri Island at around 11:27 a.m. ET Friday, according to the Japanese military.

According to data from FlightRadar24 and the Japanese Self Defense Forces, Air France Flight 293 passed just east of the splash down site roughly five to 10 minutes prior to the missile impacting the water. At the time of the splashdown, the Air France flight was approximately 60 to 70 miles north of where the missile landed, according to a review of the data.

An Air France spokesman said there were 332 people on board at the time, 316 passengers and 16 crew.

Two airways -- fixed routes established for navigation purposes -- pass within 10 miles (16 kilometres) of where the missile is believed to have landed.

North Korea has been steadily expanding the range of its missile tests away from its east coast into Japanese waters.

The North Korean missile reached a peak altitude of 3,700 kilometres before dropping into the sea near Okushiri. Passenger jets fly at around 30,000 to 40,000 feet.

In a statement Wednesday, Air France said that "North Korea's missile test zones don't interfere in any way" with the airline's flight paths and that Flight 293 completed its flight "without any reported incident."

"Air France constantly analyses potentially dangerous flyover zones and adapts its flight plans accordingly," the statement said.

The recent test wasn't the first time North Korean missiles have been seen as a potential threat to aviation. After a July 4 test, US Defence Department spokesman Jeff Davis warned the "missile flew through busy airspace used by commercial airliners" Davis said "responsible nations" should give notice before conducting missile tests, adding not doing so put planes, ships and spacecraft at risk.

"We did it for our THAAD test over the weekend. We did it with our ATACMS test, or ATACMS exercise that we did with the Republic of Korea Friday night ...," he said, referring to the Army's Tactical Missile System.

"Irresponsible nations fire these things off without putting out notice."

The chance of an unaimed missile striking a plane are "billions to one," according to aviation safety analyst David Soucie, but the ramifications are potentially huge and create a difficult decision for airlines operating in the area.

"Does it start a war? Is it an act of war? The impact of what could happen if that did occur are more than just a cost-benefit analysis," Soucie said.

Under guidelines issued by the International Civil Aviation Organization, a UN agency tasked with governing air safety and other matters, states have the "responsibility to issue risk advisories regarding any threats to the safety of civilian aircraft operating in their airspace."

"Said threats may include, but are not limited to, armed conflicts, ash clouds due to volcanic eruptions, missile tests and rocket launches," the guidelines state.

South Korea has warned since at least 2014 that North Korea fails to issue notices to airmen (NOTAM) regularly when conducting missile launches. Such notices are issued to warn pilots and airlines of potential risks during their flights.

In March 2014, Seoul said a passenger jet passed through the trajectory of a North Korean rocket in a "very dangerous" fashion.

North Korea is "clearly breaching international norms" by failing to issue notifications, said Peter Harbison, executive chairman of the Australia-based Centre for Aviation.

Japan's Ministry of Foreign Affairs said that it issued a warning to all vessels and aircraft operating within its exclusive economic zone eight minutes after the launch of the North Korean missile.

Air France confirmed it received the warning, but the message "did not specify any indication or instruction requiring an operational action on the part" of the airline. Two NOTAM messages were published but not transmitted to the crew because "the event had already passed when they were sent by the Japanese authorities," the airline said.

Failure to issue proper guidelines can result in tragedy. During the 2014 conflict in Ukraine, airlines were told to fly above 26,000 feet (7,900 meters), a level at which they were believed to safe from ground attack.

However, according to a comprehensive report into the downing of Malaysian Airlines Flight 17 by Dutch authorities, the Ukrainians may have failed to take into account the presence of weaponry posing a risk to civil aviation in the conflict zone.

The report concluded a missile -- which had a far greater range than other weapons in the area -- brought down the plane, killing almost 300 people on board.

Should a North Korean missile come close to a passenger jet, it's "probably not something you would be able to detect like you detect another aircraft," a Hong Kong-based commercial pilot said.

"You wouldn't even know it was coming," he said, speaking anonymously as he was not authorized by his employer to discuss sensitive matters.

"The issue is North Korea is firing missiles out of its airspace jurisdiction. ... It's quite a big threat."

A decision to adjust flight paths to compensate for any potential risk from North Korean activity would likely be a costly and difficult one, said Soucie" The bigger picture is the fact that no one really has the authority to mandate a no-fly zone" he said. "It's up to each airline to make that decision."

Such a decision by an airline would require a significant diversion from usual flight paths and airways, potentially racking up large fuel costs for long-haul flights such as those bound from Asia to Western Europe.

The Hong Kong pilot said it would likely force some flights to carry out "technical stops to land and refuel somewhere" to complete their routes.

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