Aircastle (NYSE:AYR) is a global company that acquires and leases commercial jet aircraft to commercial and cargo airlines. Aircastle also invests in other aviation assets, including debt securities backed by commercial jet aircraft. As of February, 2008, Aircastle has acquired and committed to aquire more than 130 passenger and cargo aircraft, currently priced at $5.7 billion . All of Aircastle's aircrafts are high utility, as they are generally modern, operationally efficient jets with a large operator base and long lives.
The aircraft leasing industry is mainly tied to the supply and demand of aircraft, which is affected by the overall health of the airline industry. Aircastle leases their airlines on an operating lease basis, thus retaining the benefits or bearing the risks of the risidual aircraft value upon expiry of the lease. Operating leases are often used by airlines that need greater fleet flexibility and lower capital commitment. Aircastle's largest clients include U.S. Airways, Sterling Airways and Swiss International Airlines. 
Aircastle's main revenue derives from operating leases and has a very high customer concentration. As of March, 2006, the company's four largest customers (U.S. Airways, Hainan Airlines, Swiss International Airlines, Air India) accounted for more than 50% of total revenue. 
As seen in the revenue vs. operating chart below, Aircastle has experienced significant growth in the past 3 years. From 2005 to 2007, the company grew its revenue by an average of 330% annually, and increased its operating income by an average of 509% per year. 
The bulk of Aircstle's business comes fom outside the U.S., with Europe and Asia accounting for 47% and 27% of total revenue respecitvely. As North America only accounts for 10% of total revenue, Aircastle is slightly less vulnerable to the volatilities in the U.S. domestic airlines industries.
The key operating metrics for the airline leasing industry are RASM (Airline Unit Revenue) and lessor lease margin performance. Aircastle has an opereating margin of 56.59% (as of 2007) compared to an industry average 26.26%.  RASM is airline revenue divided by capacity, measured in available seat miles, and is an indicator of airline performance and lease fees.
Further tightening government regulations on the airline industry post-9/11
Rising fuel costs have lead to decreasing profit margins for most airlines, especially in the US airline industry. This has lead to lower aircraft leasing demand and fees, which have a negative impact of Aircastle's future revenue.
Delays in the production of A380 and 787 airplanes and tight supply forces more airlines to lease aircraft at higher fees. As Aircastle's aircrafts are primarily sourced in the secondary market, they are mostly unaffected by this supply constraint and can benefit from potential increased revenue.
Demand for leased aircraft from airlines in emerging markets, such as Asia, where Aircastle has significant exposure continues to be strong so far and has been resilient to the economic slowdown in the US. This stems from the increasing demand for air travel from growing middle classes in emerging markets such as China, India, Russia and Eastern Europe.
The aircraft acquisition and leasing industry is highly competitve and fragmented. Globally, there are more than 260 airlines and 450 leasing companies, carrying a total inventory list of 19,000 aiplanes.  The companies compete in the leasing and re-leasing of aircraft, as well as in aircraft acquisition and sales. Thus Aircastle competes with airlines, aircraft manufacturers, other aircraft operating lessors, aircraft brokers and financial institutions. They main competition includes:
Aircastle differs from its competitors in that it mainly focuses on seeking out high utility used aircraft and does not pursue manufacturers for new orders.