I didn't say oldest. I said oldest to not have been through a bankruptcy.

From my understanding, Piedmont at least once, filed for bankruptcy. I could be wrong, this was what I heard from our management a few years ago. A quick google search found this link showing PDTs bankruptcy filings.(Toward the bottom)

https://www.washingtonpost.com/archive/business/2004/09/20/bankruptcies/fca67aec-09bd-4334-8ca6-c9a28bd7862f/?utm_term=.be4414bf43c6

And

http://bankrupt.com/misc/usair_amended_plan.pdf