In recent years, the air transportation industry has faced several serious challenges.
Airlines have increasingly become targets of terrorism related to international political
tensions. The tragedy of September 2001 involving terrorist use of four aircraft in the
United States, and the rise of terrorists targeting airports has had serious economic effects
on the industry. Other factors, such as the SARS (Severe Acute Respiratory Syndrome)
epidemic of 2003 and the Avian Flu have also had a negative impact, resulting in the
reduction of air travel.