That became apparent following outrage over the doomed Malaysia Airlines jet's flight path through volatile eastern Ukraine. The argument became more acute on Tuesday, when international airline carriers set their own aeronautical boundaries, ordering their Tel Aviv-bound commercial planes to divert amid rocket attacks.
Air Canada, Dutch carrier KLM, Germany's Lufthansa, Delta Airlines and Air France on Tuesday joined the U.S. Federal Aviation Authority in deciding to cancel scheduled flights to Tel Aviv after a rocket fired from Gaza landed near the city's Ben Gurion Airport.
Israel, in protest, called it an overreaction and insisted Tel Aviv was secure.
'A risk-mitigation exercise'
The airline industry's precautionary response came a week after the Malaysia Airlines Flight MH17 crash in Ukraine — a disaster the U.S. believes was caused by a surface-to-air missile launched by pro-Russian rebels who are clashing with Ukrainian forces.
While Israel has closed civilian airspace before, it didn't do so this time around Tel Aviv.
"The Israelis haven't closed it, but it's a risk-mitigation exercise by the FAA and the operators," said Nigel Waterhouse, a Montreal civil aviation expert who has consulted for Transport Canada on aircraft design.
As a pilot, Waterhouse said, he believes "it's crazy to be flying anywhere near where they're shooting rockets."
But the Malaysia Airlines disaster is apparently driving the industry to be more risk averse.
"The big issue is liability," Waterhouse said. "If now, an aircraft flies into a high-risk zone and it's shot down, fingers are going to be definitely pointing, even more so than with the Malaysia incident."
FAA warned to stay away from Ukraine
In the MH17 case, Ukraine's airspace at 9,000 metres was open and had been deemed a safe corridor when the jet was cruising at that altitude.
Amid calls for an international investigation, airlines and aviation authorities around the world ordered flight routes to circumvent the region near the Crimean Peninsula.
"It’s a mistake a lot of people were making, and until now, very few were avoiding," said retired Air Canada and Canadian Air Force veteran Russ Cooper.
"The only ones that were basically opting out [of flying over the region] were the Americans because of the FAA."
The U.S. Federal Aviation Authority warned American aircraft on April 25 to steer clear of the region near the Crimean Peninsula, where Ukraine’s military and pro-Russian separatists have clashed for months.
Air Canada released a statement last week confirming the carrier "has been proactively avoiding airspace over the region for some time already."
Before the disaster, there appeared to be little reason for concern given the high altitude travelled by passenger jets, noted Pierre Jeanniot, a former Air Canada CEO who once negotiated flight routes over conflict areas.
"I would think there are a lot of precedents around the world," Jeanniot said. "I mean, we flew over Afghanistan at those levels. We fly over Syria, we fly over Iran and Iraq … and we fly over a lot of Middle East points. We fly over Egypt, over a lot of potential problem areas, and no incidents have taken place. No major events."
Earlier in the month, however, Ukraine claimed that a military transport plane was downed by a Russian missile.
That should have raised red flags among risk-reduction analysts, said Arthur Rosenberg, a New York aviation lawyer.
"I don’t think anyone can dispute the fact that this is a war zone and no commercial airline should have been flying — in my view — in, near, or around this area," he said.
Knowledge of open or closed airspace and "war exclusion zones" are communicated through documents called "NOTAMs" (notice to airmen), which would be reviewed by everyone from the airline to the pilot, air traffic controllers and dispatchers.
Studying up on NOTAMs is part of routine flight planning, explained John Maris, president of the Ontario aerospace research firm Marinvent.
Bulletins issued by each country
"The NOTAM will give you whatever information you need to stay out of trouble. So in Quebec we’ve got fireworks displays in the summer, and they’ll establish a little zone above the fireworks display prohibiting flight over that area, and give whatever altitude limit is required," he said.
For a space shuttle launch, a NOTAM would inform pilots whether an area has become "hot" or active, and indicate whether a patch of airspace that is normally dormant should be avoided at any altitude.
The publicly accessible documents would also advise pilots about whether an airport is closed, a taxi runway is congested, or whether local air shows or military test sites are active in the area.
"If you're going to fly all the way across Europe, you'll get the French NOTAMs, the German NOTAMs, Greek NOTAMS, all in one big dump, if you will. It's up to you as a pilot to decide how you'll react to them," said Maris, who has conducted aviation accident investigation work.
The non-profit Nav Canada runs and lists national NOTAM data. Ukraine’s civil air navigation system publishes its own.
If carriers failed to follow Ukraine’s aeronautical advisories then, they’re much more likely to heed them now.
"I guarantee there’s not going to be a commercial airline within a thousand kilometres of that place now," said Mike Boyd, a Colorado-based airline security consultant and president of the Boyd Group.-
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While North American airlines exercised caution around Russia and Ukraine, Boyd said, "you can make the argument legitimately that Malaysia should have known better than to be there."
Yet it appears the Malaysia flight never actually violated closed airspace near Donetsk in Ukraine’s east.
A deadly presumption
Eurocontrol, which co-ordinates European airspace, said its records showed the Malaysian airliner was flying at a cruising altitude of roughly 10,000 metres, or 305 metres above restricted airspace.
Although the airline company may have believed that to be a "safe" distance from the reach of military ground fire, Boyd said that was a deadly presumption to make.
"The argument would be that at that altitude, the airplane is not a threat," he said. "Who’s going to shoot down an airplane at 35,000 feet?"
Cooper called that a grave "miscalculation."
The BUK missile launcher, also known as the SA-11, is sophisticated radar-guided weaponry that can launch missiles with a range of up to 24,000 metres.
Saving on fuel costs
While flying in the Persian Gulf during his air force days, Cooper said, he narrowly escaped a variant of the same missile fired at his fighter jet by the Iraqi Republican Guard.
"My F-18 at the time had pretty state-of-the-art (radar) jammers and I had a lot of training with regard to how to avoid missiles, and I had to use every trick in my book to avoid being taken down by one of those SA-11s," he said. "There’s no way a civil airliner could come out of this on the bright side."
But knowing that transport planes have already been taken down in the region, why would any airline continue to take the risk in that airspace?
Cooper, who was tapped after the Sept. 11 attacks to work as a member of the Air Canada Pilot’s Association Security Committee, supposes the main reason in many cases is companies don’t want to hurt their bottom line.
MH17's flight path was considered to be cheaper, busier and more direct.
"Airlines run on a real tight profit margin and one of the biggest factors is fuel," Cooper said. "You go around things, you make your travel longer, you burn more fuel, you lose more money, and sometimes, saving money is the name of the game."