After an unprecedented drop in air travel due to the coronavirus, passenger airlines are being forced to make long-term, make-or-break decisions at a time of great uncertainty and minimal cash flow. So how are they planning to survive? WSJ finds out. Composite: George Downs/The Wall Street Journal The downturn buffeting the global aviation industry has slashed demand for jet fuel, posing yet another obstacle to the oil market’s recovery. Cars and trucks quickly returned to the road when officials lifted restrictions on movement this spring, sparking a revival in gasoline and diesel consumption. Planes have been slower to take back to the sky, hobbling sales of kerosene, or jet fuel. Demand…