The Post spoke to several aviation experts about a number of factors that may have contributed to the fatal collision.

Gripping footage of an air rescue operation shows helicopter crews hoisting three backcountry skiers from a mountain in Washington state.

American Airlines flight 5342 was approaching to land in Washington DC from Wichita, Kansas when it collided with a military helicopter.

Footage of the rescue mission last week shows crews piloting two helicopters for King County Sheriff's Air Support team over thick wilderness near Stevens Pass, a ski area in Washington's Cascades.