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The past two articles regarding aircraft rescue operations and structural fire departments – “Aircraft Rescue & Structural Fire Departments” in the November 2012 issue of Firehouse® Magazine and “Dangers to Responders at General-Aviation Accidents” (April 2013) – served as building blocks by focusing on emergencies involving light-aviation and general-aviation aircraft.
Beginning with this article, we focus on emergency responses involving commercial aviation and how these incidents are going to differ from those involving smaller aircraft.
In the U.S. alone, there are about 28,500 commercial flights a day. That equates to about 9 million flights each year and about 732 million people in the skies over the country. Commercial aviation is still the safest mode of transportation per miles traveled. This is a positive for the airline industry, but with an aviation system that is expected to continue its growth at a rate of 3% to 5% a year for the next decade, the potential remains for accidents to occur.
An obvious reason why commercial aviation accidents are so different from light- and general-aviation accidents is that the casualty counts can be much greater than with a small aircraft or an executive-type aircraft. Another problem for emergency responders is not only casualties, but caring for the uninjured.
Types of impact
Many well-documented commercial aircraft crashes have taken place over the past decades and survival factors usually come down to the type of impact. Destruction of an aircraft can depend on many factors, but the “attitude.” or angle at which an aircraft strikes the ground, will have a great deal to do with passenger survival. An aircraft that strikes the ground at an extreme angle will usually result in a high-fatality incident. These crash-site footprints can be relatively small and compact. Remaining pieces of the aircraft tend to be smaller and less identifiable. In many cases the recognizable parts of the aircraft will be the engine, tail section and landing gear. These parts are usually very dense or strong in their construction and sustain impact forces better.
Aircraft with the ability to touch down in a more “normal” landing configuration, if you will, may have a much more survivable outcome. This will vary greatly depending on what is on the ground and what the aircraft does or does not strike. These scenes will be the ones that will require the most fire, EMS and law enforcement intervention and will test the limits of emergency plans and services. Whether the accident is high or low impact, it can have a profound impact on emergency services and the community in general.
Basic construction practices that have been discussed in previous articles still hold true, but in bigger aircraft the parts and construction are more robust. The primary material is still aluminum panels placed over a skeleton called stringers (sometimes called longerons) and formers. This creates the fuselage or cabin. The wings, engines and landing gear are attached to that. The aircraft skin is usually only a few millimeters thick and that thickness can depend on the model of the aircraft and the skin’s location on the airframe.
On the inside of that thin aircraft skin is a small layer of insulation, some light and call button wiring and tubes for airflow and then a plastic panel for aesthetics and finish. Then windows, seats, control surfaces are added along with, in some cases hundreds if not thousands of miles of wiring, depending on the aircraft, and then made to fly. Aircraft are very complex, intricate machines and like has been said in previous articles, if you know how they go together they are easier to take apart.
Any aircraft that flies high enough needs to be pressurized for passenger and crew survival. Rescuers must understand that making entry into an aircraft that has the ability to be pressurized is different from entering a non-pressurized aircraft.