11Fan has it right. This is a good will payment. Read your homeowner's insurance policy. Pretty much every homeowner's insurance policy contains a provision (a "good neighbor" clause) to pay anywhere from $1000 to $5000 to someone injured in your home, regardless of fault.

People who feel that they've been treated fairly and well are far less likely to sue. If this payment by USAir stops even one lawsuit, it will have paid for itself.

$5000 also isn't that much money. Try packing a checked bag, and a carry on for a vacation, and add up how much everything costs. Then throw in a couple nights hotel in NYC, incidental expenses, and some renumeration for the inconvenience of having gone wading in the Hudson, and you've just blown through the $5000.