alt Hacker News> Why would they be using flight computers from before 2002?
Because getting a new one certified is extremely expensive. And designing an aircraft with a new type certificate is unpopular with the airlines. Since pilots are locked into a single type at a time, a mixed fleet is less efficient.
Having a pilot switch type is very expensive, in the 50-100k per pilot range. And it comes with operational restrictions, you can't pair a newly trained (on type) captain with a newly trained first officer, so you need to manage all of this.
I think you're confusing a type certificate (certifying the airworthiness of the aircraft type) with a type rating, which certifies the pilot is qualified to operate that type.
Significant internal hardware changes might indeed require re-certification, but it generally wouldn't mean that pilots need to re-qualify or get a new type rating.