On January 15 2009, six minutes after takeoff, US Airways Flight 1549 was ditched into the Hudson River, partly a result of the heroic efforts of Captain Chesley B. Sullenberger. The aircraft had sustained perilous engine damage due to a bird strike. With both engines disabled and therefore incapable of generating thrust, the plane had to be diverted to the nearest possible strip of land. However, as the plane lost altitude, the pilots reasoned that the least catastrophic route of action was to ditch the plane into the Hudson, an option that would not be as bad as a possible failure to return to the nearest runaway as the energy gradually runs out. In quite an extraordinarily rare occurrence, the plane did indeed land successfully in the river in what has since been dubbed “The Miracle on the Hudson”, largely because until then, emergency landings on water were unheard of. All 155 on board survived and no fatalities or serious injuries were recorded.
It is obvious that such critical moments required split-second decisions, while at the same time, ensuring maximum success of rescue. The pilots had activated the auxiliary power unit (APU) which is a small gas turbine that supplements main engine operation and the ram air turbine, which is an air-driven hydraulic device that generates electrical power to the plane’s control systems in case of engine failure. But, could the pilots have resorted to reviving thrust in the engines instead? That might have ensured a return to the runway and thus a safer landing. But, that would have also required diverting the flight control system to DIRECT LAW, a mode that requires the pilot to trim manually and control the engines without envelope protection, putting the orientation and controllability of the plane in jeopardy.
The pilots did indeed try to restart the engines, an attempt that unfortunately failed. Given that the plane would most likely not be able to make it that far to the nearest airport, the pilots had no choice but to land the plane into the Hudson. An experienced glider, Captain Sullenberger was able to manoeuvre the gliding descent of the aircraft into staggering perfection. He flew the aircraft into a 10 degree nose-up altitude to ensure that the wings were level with the water surface. The plane, ultimately, descended with the tails hitting the water first upon impact, allowing the plane to drag to a halt. The landing manoeuvre ensured that the fuselage was intact, such that the plane would not sink down all too soon. It is likely that the pilots also used the plane’s ditch button, which ensures that the fuselage is sealed preventing water from seeping in and thus maintaining the plane’s buoyancy. The landing was a success – a miraculous one.
Bird strikes are not extraordinarily rare events and they have, in the past, threatened flight safety and caused expensive damages. Could the airflight ecosystem be engineered such that it is not particularly attractive for birds? Could a radar system be employed to identify and track the birds in the vicinity of the airport to ward off impending strikes? Are lessons from Flight 1549 being incorporated into today’s safety protocols?
It is often said that prevention is better than reaction and the incident of the Hudson provides a timeless lesson: the imperative to reduce risk to the best of one’s ability and to anticipate what needs to be prepared in advance.
Featured image credit: Exosphere3D