NEW YORK (BLOOMBERG) - The nightmare year of 2020 brought the airline industry's first decade of sustained profitability to a shuddering halt. The coronavirus pandemic tore through in a tumultuous, unprecedented way - leaving carriers in a deep hole, along with a constellation of aerospace manufacturers, airports and leasing firms. 2021 is shaping up to be a transition year for an enterprise that takes passengers on the equivalent of 208 million annual trips around the globe. At best, the path ahead will be bumpy, with progress toward a return to travel dependent on the pace of vaccine roll-outs, access to capital, government policies and the unpredictability of a virus that's not yet fully understood. Still, there will be leaps, including the first commercial flights to near-space.