That still leaves the question of "why?". If he wanted to commit suicide he could have had an "accident" in a light aircraft instead of murdering 238 people, and the entire point of terrorism is for everyone to know it was you.
The secrecy was the point. For whatever reason, he didn't want to be remembered as suicidal and murderous.
Odd choice, now that it looks like he will be.
> There is a lot of evidence to suggest the pilot did this intentionally …