By Idrees Ali and Andrea Shalal
WASHINGTON (Reuters) - The Pentagon on Thursday forecast a 3 percent drop in acquisition costs for Lockheed Martin Corp’s (N:LMT) F-35 fighter jet, but said plans to use the jets six more years would add about $45 billion to the projected operating costs through 2070.
The Defense Department's annual report on major weapons programs forecast the total cost of the stealth fighter jet program would reach $1.5 trillion by 2070 including development and procurement, as well as operating costs and inflation.
That was up from the previous estimate in 2014 of $1.41 trillion.
The F-35 program chief said the projected cost increase in the Pentagon's biggest arms program was due largely to a decision by the services to reduce the jets' annual flying hours to 250 hours from 300.
The jets have a service life of 8,000 hours, meaning they would be flying for an additional six years or 1.6 million flying hours, which in turn would add significant operating costs, Bogdan said.
Barring that decision, he said, the program would have seen a $22 billion drop in operations and maintenance costs, with annual Navy and Air Force costs down between 2 to 4 percent due to the increasing maturity of the new warplane.
Pentagon officials on Wednesday said the program had made steady improvements in cost, schedule and technical performance over the past year, but still faced delays in software development and a complex computer-based logistics system.
Projected operating and maintenance costs, including inflation, are now seen up 10 percent to $1.12 trillion from $1.02 trillion in last year's report.
But Bogdan dismissed the relevance of the long-term forecast for operating and maintenance costs, given the difficulty in forecasting fuel costs that far into the future.
Lockheed is developing three models of the jet for the U.S. military and nine countries that have already placed orders: Britain, Italy, Turkey, the Netherlands, Norway, Australia, Japan, Israel and South Korea.
In the statement, the program chief said the F-35A had a decrease in cost of $1.8 million per jet while the remaining two variants saw a decrease of approximately $1 million per jet.
The Pentagon report forecast the average cost of the F-35A conventional takeoff and landing model would be $100.6 million, including inflation. Bogdan has said he expects to lower the cost of the jets to around $85 million per copy by 2019.