It's not on the sidelines. Like 0.001% of "cash" is actually cash. Apple holds like a third of its "cash" in equities. Airlines could do the same, or hold s

It's not on the sidelines. Like 0.001% of "cash" is actually cash. Apple holds like a third of its "cash" in equities. Airlines could do the same, or hold short-term debt, or pay down their own debt (which would free up capital for other uses). (They could also hold long-term debt in other companies, but I'm not sure where that shows up in the balance sheet.)