Is it safe to purchase United Airlines plane tickets for a June/03 flight? Is there any safety net in case United goes out of business prior to 6/03?

United won't go out of business prior to June 2003.

You'll be fine - buy the tickets.

I would go ahead and buy them. It is highly unlikely United will go out of business before then. If they were to go out of business while you are in transit, one of the other carriers would most likely honor your tickets. Be sure to charge your tickets to your credit card, though--not cash.

I tried to buy tickets through Delta a few days ago. The flight I wanted was sold out and the ticket agent checked the closest United flight to see if she could get me tickets with them. The are in some kind of partnership together because my Delta Skymiles will also work with United.

Buy the tickets. Or better yet, call Delta and find out more info about what I just told you. Good luck.