The State's largest single expenditure on aircraft is likely later this year when the Air Corps receives its first medium-lift helicopters and, as is expected, the Government jet is replaced.
Tenders for the helicopters are at an advanced stage, with a shortlist of four.
During the year the Government is likely to replace its Gulfstream IV jet, which has been in service since 1991.
No tendering process has begun for a new jet but Air Corps sources say that likely contenders will include Gulfstream Aerospace Corporation in Savannah, Georgia, and Boeing Business Jet (BBJ), part of the Boeing Corporation.
The Boeing jet is larger than the Gulfstream and may be preferred for transporting delegations on EU and other business. Sources say the cost will be between £50 million and £60 million.
The new version of the existing Government jet is the Gulfstream V and GIV and about 400 are in service around the world. Gulfstream remains the leading manufacturer of business jets.
The Gulfstream V is capable of flying 6,500 nautical miles at speeds up to Mach .885 with eight passengers and a crew of four at altitudes up to 51,000 feet.
Boeing Business Jets announced last October that it had sold 71 aircraft since it was launched as a joint venture between The Boeing Company and General Electric in 1996. The new BBJ2 model has a range of 7,130 nautical miles and a speed of around 550 miles per hour. The aircraft is an adapted Boeing 737
The four tenders under examination to supply the Air Corps with its medium-lift helicopters are agents Bond, of Scotland, which already supplies east and south coast maritime rescue service; EH Industries, which manufactures the EH101; Eurocopter, the EU consortium which manufactures the Cougar; and Sikorsky, whose main medium-lift aircraft is the F92.
The helicopters are likely to cost up to £15 million each. It is expected three will be used as troop carriers and two for search and rescue.