On December 28, 1978, United Airlines Flight 173, a McDonnell Douglas DC‑8‑61 (N8082U), was on approach to Portland, Oregon, after a routine flight from Denver. When the landing gear was extended, the crew heard an abnormal thump and felt a yaw; the green down‑and‑locked light for the right main gear failed to illuminate. The captain, a seasoned aviator, elected to abort the landing and orbit southeast of the airport while the crew diagnosed the problem. For roughly one hour, the cockpit became a workshop of troubleshooting and passenger briefings. The first officer and flight engineer repeatedly raised the fuel state, but their warnings were indirect and failed to break the captain’s fixation on the landing gear. At 18:13 local time, the flight engineer declared, “Not enough. Fifteen minutes is gonna really run us low on fuel here.” Moments later, the engines flamed out one by one. The aircraft crashed into a wooded suburban neighbourhood six nautical miles from the airport. Ten souls were lost—eight passengers, the flight engineer, and a flight attendant—while 179 survived.