The suspected shooting down of a large passenger plane while flying at altitude presents airlines and their passengers with an extremely serious new development in air travel, according to aviation experts.
They also question the future of Malaysia Airlines - caught in the global glare of bad publicity following the disappearance of flight MH 370 earlier this year.
If today's incident is confirmed as a deliberate act then Ukraine airspace could well be closed down, meaning diversions for UK carriers who currently fly to and over the area.
"This could be a very serious development," said David Kaminski-Morrow, air transport editor of Flightglobal magazine.
He went on: "If reports are true, we are not talking about small-arm fire but serious weaponry. Normally even if planes fly over a war zone they can go high enough for the conflict not to be a worry.
"Any decision about the opening or closing of Ukranian airspace will be a matter for the Ukrainians. It could well be that part or all of that airspace will now be closed.
"Also, individual airlines, including UK carriers, could decide to detour around Ukraine."
Mr Kaminski-Morrow continued: "It's really quite incredible that it should be Malaysia Airlines involved in this, after what happened earlier in the year.
"This is not a small airline on a faraway route. This was a major airline flying from a European destination to a capital in the Far East. There must be serious concerns about how the airline can recover from this.
"There will obviously be political as well as aviation concerns from all this. This will run and run."