Matt Whiting wrote:

Jim Macklin wrote:

How cold did it get in Denver? Aluminum and plastic have
different contraction rates with cold. Plastic also gets
brittle with cold. Wind flexes wing, which also flexes
fuselages, erg---cracks.

It can't be as cold as the jets routinely see above 30,000 feet. I
suspect the wind was carrying stones or ice chunks or something like
that which cracked the windshields.

I suspect the the crews turned on the electric windshield heating without
proper warmup when it was very cold, and the cracks resulted from thermal
stresses in the windows. The cracks were reported to have happened in the
air, where flying rocks would be rare, and not on the ground.