Because buying an aircraft on credit lacks forsight let me explain with numbers...
Lets look at getting hold of C-AFUF a B739-900ER HGW 0.3 years old, available on the market in gatow now.
Base Price: 69,929,115 AS$
Down Payment: 3,496,456 AS$
Installment: 255,510 AS$
Leasing Depot: 3,496,456 AS$
Leasing Rate: 349,646 AS$
So then we have 3 options....
Cash (buying outright)
Thats simple, thats going to cost you 69,929,115...which is a lot of money to spend. Only large airlines can afford to do this. To give you an idea you can almost lease 20 of the same aircraft, whats going to make you more money, 1 or 20? So then the other kick in the balls is when you decide to either replace or a 737-900 is too big/small for your airline. You want to sell it! So you put the aircraft back on the market and your fairly unlikely to sell at even 80% of cost as you need another airline to buy it. The only gauruntee of selling it is to put it on the market for 2 weeks at 10% of its worth. Then AS will buy it off you. so that would be 69929115/10 = 6,999,291. Your loss on the aircarft = 63milAS! So if you buy an aircraft you have to be very sure you want to keep it. Bare in mind thats worst case.
Credit
So you buy on credit, where the bank buys it for you and you pay the bank back. You would have to put down the down payment (3,496,456) once. After you have paid this every week you will have to pay the installment which is 255,510, and then interest. With a AAA company you will be paying around 1% interest on whats remaining. So 69,929,115-3,496,456=66,432,659 to repay. So 1% of that is 643,265...so every week you will be paying around 643,265+255,510= 898,775, slowly decreasing per week. Bare in mind thats a AAA company, a BB company which is what a new airline usually is may have a 5%+ rate. Also at the end of the day you have to sell the aircraft which guess what....see above!
Lease
You pay the deposit once...3,496,456, and weekly pay 349,646. If you decide to get rid of the aircraft you send it back to leasing company and get your 3,496,456 back...loss made....0! Far more flexibility and no loss
Also try not to buy aircraft brand new from Boeing/Airbus etc. Have a look at the used aircraft market. You can sometimes get the same aircraft (maybe 1 month old) for substantially less than than factory prices.
Hope this makes sense!
Ian