专家：导弹击中马航飞机 机上人员只能绝望等死

The explosion captured in a video likely didn't happen until the Boeing 777 aircraft crashed into the ground, Timothy Holt, a professor at Embry-Riddle Aeronautical University told ABC News.

"In this case, it looks like most of the aircraft disintegrated upon impact [with the ground]," he said.

Malaysia Airlines Plane Brought Down By Missile in Ukraine

'Bodies Are Everywhere': Witness

Live Updates: Malaysia Airlines Plane Crashes in Ukraine

What happened to the aircraft depends on where the missile struck, he explained, saying that if it pierced the wings -- where the fuel is located -- the plane might have exploded mid-air.

But with this explosion, "it looks like most of the gas was still contained," Holt said.

"You don't see a fireball in the sky ... you see the flame when it hits, you see the black clouds coming out."

Commercial planes like the one that was taken down today in eastern Ukraine carrying 295 people don't have the equipment that lets crews know if a missile is tracking the aircraft. The only way a pilot might know is if he saw the missile fired from the ground.

"If you had some warning in a commercial aircraft, if you see a visual, the best you could hope for is maybe doing a quick descent, taking it into a turn," said Holt, who flew surveillance aircraft in the U.S. Navy for about 15 years. "But we're not talking a high-performance jet that's going to try to out-maneuver a missile. I don't see a way pilots really could have avoided it at that point. And commercial pilots aren't trained for missile strikes."

It's not yet clear if passengers, whose remains are scattered in Hrabove in eastern Ukraine, died immediately when the missile struck or possibly minutes later, when the plane crashed to the ground.

"A lot depends on missile type and where the missile impacts," Holt said.

A U.S. official told ABC News that a surface-to-air missile struck the Boeing 777 that went down today in Ukraine near Russia's border. It is unclear whether the missile was fired from inside Ukrainian or Russian territory and who fired it, the official added. Debris and remains are spread across 10 miles in the area.

The flight, carrying 280 passengers and 15 crew members, was traveling from Amsterdam to Kuala Lumpur.