[jen20]

It's also not guaranteed which plane will fly which route. Every airline has "substitution" rules in their conditions of carriage, and frequently use them.

[mopsi]

Depends on airline. Southwest, for example, has Boeing-only fleet. JetBlue has only Airbuses and Embraers.

The odds of buying a JetBlue ticket and ending up on a Boeing are fairly low compared to flying Southwest.

[frozenlettuce]

Boeing just bought Embraer, but I assume that it will take some time until they the quality of products start to fall

[jonny_eh]

Plus, flights get cancelled, and passengers get re-routed last minute.

[tedunangst]

I can't recall any plane crashes that also involved a plane switch. So getting bumped to a different plane type and crashing is incalculably rare.