(Read more: Copa Holdings Tops Q4 Earnings Estimates, Ups Dividend). 2. United Airlines, Southwest Airlines and American Airlines currently have 14, 34 and 24 Boeing 737 Max jets in their fleet. While American Airlines cancelled 737 MAX flights until Aug 18, 2020, United Airlines and Southwest Airlines did so until Sept 4 and Aug 10, respectively. The decision followed Boeing's announcement that approval from regulators for flying the jets again is not expected before mid-2020. In fact, United Airlines anticipates cancelling in excess of 7,700 flights from June through September. As a result of U.S. carriers extending the grounding period, these airlines are likely to operate without the jets for the second consecutive summer season. This might dent their profitability. 3. With air-travel demand continuously surging, the risk of air travel causing environmental damage is also prevalent unless carriers take measures to counter it.