The International Civil Aviation Organization on Friday (local time) denied it had closed an air route over eastern Ukraine following the crash of a Malaysian airliner, saying it had no power to do so.
Malaysia's transport minister said earlier that the Montreal-based UN aviation body had shut the route after a Malaysia Airlines airliner was brought down in eastern Ukraine on Thursday, killing all 298 people aboard.
"ICAO does not open or close routes. We do not have an operational role," chief ICAO spokesman Anthony Philbin told Reuters.
Airlines rely on governments to tell them which routes are safe and do not compromise on safety, the head of the International Air Transport Association said.
"At this time, it is important we are very clear: safety is the top priority," IATA chief executive Tony Tyler said in a statement.
"No airline will risk the safety of their passengers, crew and aircraft for the sake of fuel savings. Airlines depend on governments and air traffic control authorities to advise which air space is available for flight, and they plan within those limits."
In response to the tragedy, German authorities have warned airlines against flying over all crisis zones, not just eastern Ukraine, a spokesman for the transport ministry said.
Airlines diverted planes to avoid eastern Ukraine and on Friday (local time) Ukraine closed its airspace in the area.
Germany has now gone one step further by including all conflict zones in its warning to Germany's 144 aviation firms.
That would appear to include other areas such as Syria, Iraq and Afghanistan. But it is up to individual countries to close their own airspace, as Ukraine did.
Lufthansa, Germany's main airline, said it was in touch with the LBA to get more precise information on what crisis zones it was referring to.
''We expect the LBA to give more specific information on its recommendation as soon as possible, in case there have been definite changes to the security situation in certain areas,'' a spokesman said.
Joerg Handwerg, a board member at German pilots' union Vereinigung Cockpit and an A320 captain, earlier told Reuters that questions must be asked over whether planes should be allowed to fly over conflict zones.
"Flying over contested territories such as Afghanistan was previously thought of as unproblematic, because there were no weapons that could reach passenger planes at the altitudes they fly," said Handwerg, who flies medium-haul planes.
"From the point of view of pilots, the threat was of a different quality before. There were only a few flights that were classed as critical ... But now planes flying at 10,000 metres above the entire country are a risk."
AIRLINES CHANGED FLIGHT PATHS
Qantas Airways and several other airlines altered their flight paths some time ago to avoid Ukrainian air space after fighting flared up in the region, raising questions about why others did not do the same.
The issue of whether to avoid flying over conflict zones has now come into sharp focus.
International civil aviation regulators had imposed no restrictions on crossing an area where pro-Russian rebels are fighting Ukrainian forces, and the majority of carriers had continued to use a route popular with long-distance flights from Europe to southeast Asia.
But the fact that a handful of companies decided to circumnavigate the disputed territory underlined inconsistencies in airlines' approach to passenger safety.
Aviation experts said piecemeal and potentially conflicting advice from aviation regulators further confused the situation, and called for clearer guidance on which areas to avoid.
In addition to Qantas, Air Berlin, Asiana Airlines Inc, Korean Air Lines Co Ltd and Taiwan's China Airlines decided to avoid Ukrainian airspace several months ago.
Cathay Pacific Airways Ltd changed its routes some time ago, but did not specify when, and a source familiar with the situation said British Airways had also been avoiding the area where the flight went down.
"Although the detour adds to flight time and cost, we have been making the detour for safety," said a spokeswoman for Asiana, which has been diverting its once-weekly cargo flight some 150 km (93 miles) below Ukrainian airspace since March 3.
The European Aviation Safety Agency did issue a safety bulletin, accompanied by recommendations from both the UN's ICAO and Brussels-based Eurocontrol, on April 3, advising that Crimean airspace should be avoided. Russia annexed Crimea from Ukraine in March.
But those directives did not apply to the airspace over Ukraine being traversed by Flight MH17 when it was brought down.
It was not immediately possible to verify which airlines had adopted which routes.
Flight paths and altitude vary according to factors such as weather, the amount of traffic on busy corridors and flight restrictions. Flying higher helps burn less fuel, but pilots do not always get to the altitude requested when airways are busy.
NO UNDUE RISK
Malaysian Transport Minister Liow Tiong Lai said on Friday the national airline took no undue risk in flying over Ukraine, a route he stressed was approved by the ICAO and widely used by other airlines.
"We've flown this route for many years, it's safe and that's the reason why we are taking this route," Liow told a news conference where reporters repeatedly questioned why the airline chose to fly over a conflict zone.
The ICAO denied it had closed the route following the crash, saying it had no power to do so.
Thai Airways International, which had also continued to fly over the area until the crash, said there was no reason not to do so.
"Ukraine is not a war zone. Crimea is war zone," spokeswoman Charlene Suddhimondala said.
"Whether we flew over Ukraine really depended on fuel and weather conditions. If the weather was good, sometimes pilots opted to fly over Russia which meant passing through Ukraine."
Some independent experts did not agree.
Geoff Dell, an accident investigation and safety specialist at CQUniversity in Australia, said airlines had their own intelligence operations which should be making decisions in such situations.
"It's blatantly obvious they shouldn't have been anywhere near it," Dell, who was working as a senior safety manager for Qantas during the first Gulf War, said of Flight MH17.
"Any sort of unrest breaks out, civil wars or such, you change your flight path so that you don't have to go anywhere near it. Of course it comes at a cost, because you have to fly further."
SUSPECTED MISSILE ATTACK
Diverting planes is expensive for airlines, requiring more fuel and more time in the air and making some reluctant to do so without clear directives.
Flight MH17, en route from Amsterdam to Kuala Lumpur, was flying at around 33,000 feet over eastern Ukraine when it was brought down.
The United States said the plane was probably felled by a ground-launched missile strike, while Australian Prime Minister Tony Abbott said on Friday that Russian-backed rebels were responsible.
Immediately after the incident, several airlines announced that they were re-routing flights to avoid Ukrainian airspace, including Russian carrier Transaero.
As well as criticising some airlines, Dell and other experts said the onus was also on civil aviation regulators to provide clearer directives on avoiding conflict areas.
"The safety authorities themselves have much to answer for," said Chris Yates, of London-based aviation consulting firm Yates Consulting.
Ukrainian authorities had closed the flight path from the ground to around 32,000 feet, according to Eurocontrol, the agency responsible for coordinating European airspace. Flight MH17 was flying 1,000 feet above that.
After the crash, the International Air Transport Association (IATA) said that "based on information currently available it is believed that the airspace that the aircraft was traversing was not subject to restrictions".
Some conflict areas pose more of a threat than others.
In Ukraine, Soviet-era military hardware is common, and Kiev has accused pro-Moscow militants, aided by Russian military intelligence officers, of firing a long-range, Soviet-era SA-11 ground-to-air missile at the Malaysia Airlines plane.
On Monday, a Ukrainian Antonov AN-26 transport plane was downed in a rocket attack which Kiev said may have come from Russian territory.