I generally agree with mweiss, oldiebutgoodie, Smartest Loser, and nycbusdriver.
But I think there is another problem with another Ch. 11 BK for US Airways management. That problem is that US Airways management potentially loses control of their airline. The BK judges is responsible to the creditors of the airline. His/Her responsibility is to maximize the payments to those creditors. If the BK judge feels that management's plan will not do that, he can remove management.
Take a look at what is happening in the current BK of Hawaiian Airlines. Hawaiian's CEO, a guy named Adams, took the airline to BK in a financing dispute with Boeing. He wanted lower leases. Boeing did not want to negotiate, and didn't have to because they had a contract. Adams took Hawaiian to BK in order to void the contract.
Well, the BK judge removed Adams, and the airline is currently being run by a BK-appointed trustee. That trustee, has managed a profit out of Hawaiian, and is shopping HA around to potential investors to emerge from BK. Adams, who has since teamed up with former AA CEO Don Carty, have submitted a Plan of Reorg to the court. However, so have several other potential investors, including Boeing and other former CEO's (notable, a guy named Bruce Nobles, I think).
Now, let's relate this back to US Airways... If US Airways goes to Ch. 11 again, the BK judge is required to maximize the what the creditors get from the situation. If the creditors are best served by a liquidation rather than a continuing operation, the BK judge can convert the case to Ch. 7. While this is rare, it does happen. The recent BK of Midway Airlines (the US Airways Express operator) is an example of where the CEO was still looking for investors, but when he repeatedly couldn't find any, the judge declared a Ch. 7 conversion. If such an event were to occur at US Airways, RSA would likely be at the top of the creditor list.
Just because RSA currently controls the airline, that is something that does not have to continue. It could be that a BK judge shops US Airways around as has been done with Hawaiian. In this case, RSA probably loses management control of the company. A BK judge may feel this is an appropriate course of action, since RSA has not materially changed the company's fortunes. Especially if someone like Bonderman/TPG are interested, and have a proven track record of airline turn-arounds (CAL and AWA).
Therefore, while an easy answer for management is to declare BK in order to invoke S.1113 BK/labor laws, which essentially force new negotiations, I think the probable result of those negotiations (more concessions, but probably not as much as management wants/needs) is not worth the risk (management/RSA loses control of the airline to the BK judge temporarily, and maybe to new investors permanently).