Malaysia Airlines Flight MH17 flew over airspace in east Ukraine that some other carriers avoided, but the area was viewed as an approved route by international aviation agencies months before Thursday's plane crash.
Qantas Airways of Australia and Hong Kong-based Cathay Pacific Airways were among the companies that avoided the airspace for several months. Many European carriers decided to divert only from Crimea. On April 3, the European Aviation Safety Agency and the International Civil Aviation Organization strongly recommended that carriers steer clear of Crimea after Russia annexed the peninsula.
But the April directive from EASA and ICAO, which is the aviation safety and security agency of the United Nations, did not ban flights over east Ukraine. The International Air Transport Association, which represents global airlines, also did not sound alarms to ban commercial planes in the airspace where Flight MH17 was shot down on Thursday.
Industry observers said on Friday that avoiding the world's hotspots for military and political conflict is often a judgment call. At about the time a missile hit Flight MH17, at least two other civilian aircraft were in the vicinity and could have been targeted, according to Flightradar24's plane-monitoring data on its website.
After Malaysia Airlines' Boeing 777-200 crashed on Thursday, aviation authorities in various jurisdictions issued notices for carriers to stay away from the airspace, which is now deemed dangerous.
"The primary directive of carriers is safe operations, but it is a tough business to make money in," said Robert Kokonis, president of airline consulting firm AirTrav Inc. "It was deemed before that the risk in east Ukraine was relatively low."
The airline industry is under constant pressure to run efficiently, and that means keeping costs wherever possible.
"The price of a really big disaster happening is so damaging to a carrier that I would view that as a bigger liability than the summation of higher fuel, labour and maintenance costs related to taking temporary diversions around an area," Mr. Kokonis said. "But you cannot take 100 per cent of the risk out of the aviation business. Some people make one judgment call and someone else makes another judgment call."
Taking detours for extended periods adds to the expenses of an industry in frequent belt-tightening mode.
Germany's Lufthansa said on Friday it has been avoiding Crimea airspace. Lufthansa was among the carriers that operated flights over east Ukraine until Thursday, although the company emphasized that many aviation experts believed the area posed no immediate problem. "The safety of our passengers and crew is our uppermost priority," said Lufthansa, which is a member of the Star Alliance group of carriers that includes Air Canada.
El Al Israel Airlines began using anti-missile equipment, which releases diversionary flares, for its commercial fleet in 2004. But industry analysts say that it would not make economic sense for most airlines to install detection systems and other safeguards to ward off heat-seeking missiles.
"There have been various missile warning systems proposed by defence contractors, but it's not something you would typically find on commercial aircraft to say the least. For civilian aircraft, if it's not safe to operate, you don't go there," said Chris Murray, an analyst with AltaCorp Capital. "It would be imprudent to operate in a theatre where you actually require that type of anti-missile equipment."
Malaysia Airlines, still reeling from the disappearance of Flight MH370 in March, faces a round of deep financial restructuring to survive as a corporate entity in its current form. Malaysia Airlines stock price, which fell 11 per cent on Friday, has tumbled 86 per cent over the past three years amid increased competition from low-cost carriers.