Since the first flight by the Wright Brothers, airplane safety has been a major concern for pilots, passengers and industry professionals. Safety improvements in aircraft over the past hundred years have mostly been in response to incidents both on the ground and in the air.
Technical Problems with Aircraft
The most common problem with aircraft is simply failure of the plane to operate efficiently. Events such as engine failure, loss of fuel and decompression are the most common reasons an airplane crashes. Safety improvements in aircraft over the past hundred years have been implemented to mitigate these problems, however, it is almost impossible to prevent all failures.
Engine failure can come in the form of simple stalling or even involve the complete detachment of the motor itself. Designers have made improvements over the years to allow airplanes to fly if one or more engines fail. However, when a complete separation happens, the drag from the air can often be too much for even the most experienced pilot.
Other events such as metal fatigue also cause major problems. Over the course of time, the shell of the aircraft eventually loses strength due to the constant barrage of high velocities. Unfortunately, the phenomena was not fully understood until the late 1990s and design elements were not put in place prior to this time. Modern aircraft, however, are using multiple layers of materials, notably plastics, to prevent the damage caused by metal fatigue.
Natural Phenomena Impacting Airplane Safety
A number of natural phenomena drastically impact the safety of airplanes. Since the beginnings of flight, designers have attempted to deal with the problem of the natural world on human vehicles in sky. One of the most dramatic dangers to airplane safety are lightning strikes. According to studies conducted by Boeing, lightning strikes each airplane flying in the sky an average of two times per year. Safety improvements in aircraft over the past hundred years have made lightning strikes an occurrence with little impact. Most notably, newer aircraft are designed to avoid the electrical discharge using non-conductive polymer covering the aircraft's shell.
Other atmospheric conditions such as snow, ice and volcanic ash also impact the safety of the airplane. Frost and ice can prevent an airplane from taking off and also cause crashes when the buildup is too great on the wings. Heat from the engines is redirected along the wings to melt ice and rubber balloon-type devices can be inflated to break strong ice buildup. Volcanic ash from eruptions also causes major problems for pilots as material can enter small openings throughout the plane, contaminating vast amounts of technical equipment. To combat this, the aviation industry established the Volcanic Ash Advisory Centers in 1991 to warn pilots of possible eruptions and plumes.
Bird strikes can be a major issue as well. The birds can impact the fuselage, engines and cockpit of the aircraft, damaging equipment and even causing crashes. Military vehicles have been at the forefront of preventing this event by creating bypass ducts for the birds to fly through. Since this phenomena is most common during takeoff, airports themselves have implemented preventative measures such as broadcasting audio noises of predators, growing grasslands surrounding the facility and even hiring shooters with shotguns to scare off the birds.
Preventing Human Error on Planes
Human error is the largest cause of airline crashes in the world. Failure of pilots to properly conduct procedures as well as simple fatigue can lead to catastrophe. The airline industry attempts to prevent problems associated with the activities of humans by instituting strict guidelines on time behind the wheel and training. Additional problems can arise on the ground, however. Flight controllers have been linked to hundreds of incidents due to the complexity of the job and occasional long hours. Only the continued instance of screening and training can fully create a safe and effective ground crew for the airlines.
Terrorism and Hostage Taking
Even before the tragic events of 9/11, safety from hijacking was a major concern for airlines. Many safety improvements in aircraft over the past hundred years were directly influenced by threats from terrorists and hostage takers. These improvements are designed to limit the likelihood of utilizing the plane as a tool to fulfill some political motive or simply leverage the lives of passengers in exchange for monetary rewards.
The first known instance of hijacking occurred in 1931 in Peru. While this particular event ended without incident, over the next decades, the concept became very commonplace. Groups used the threat of killing passengers to release political prisoners and goals. By the 1970s, the rate of hijackings increased to an average of 41 per year. The concept was even used by the Central Intelligence Agency against Cuban civilian aircraft and vice versa in what became a hidden war in the skies.
Above right: World Trade Centers on Fire from Plane Crashes. (Supplied by the National Parks Service; Public Domain; http://upload.wikimedia.org/wikipedia/commons/f/fd/National_Park_Service_9-11_Statue_of_Liberty_and_WTC_fire.jpg)
Terrorist attacks on the World Trade Center and the Pentagon drastically changed the dynamics of airline safety from hijacking. Worldwide, countermeasures like stiffer screening policies, air marshals and the locking of the cockpit doors all help to limit the success of airplane hijackings and an is another attempt to ensure safety for all airplane passengers.
"Aviation Safety and Security" GAO (http://epic.org/privacy/faa/gao_aviation_397.pdf)
"Top 10 Airline Safety Questions" Airsafe (http://www.airsafe.com/ten_faq.htm)