1973: Singapore buys 50 former US Navy A-4Bs and TA-4Bs stored at Davis-Monthan Air Force Base in the Arizona desert. Lockheed Aircraft Services rebuilds these as A-4S Skyhawks.

July 14, 1973: A-4S Skyhawk, unique to Singapore, makes its first flight in Ontario, California.

1974: 142 Gryphon Squadron, first A-4S unit, formed at Changi Air Base.

1975: 143 Phoenix Squadron, second A-4S unit, formed at Changi Air Base.

1980: Singapore orders another 70 A-4C airframes stored in Arizona and ships them to Singapore. Singapore Aircraft Industries (SAI) rebuilds planes as A-4S-1.

1984: Ministry of Defence plans Skyhawk engine upgrade.

1984: 145 Hornet Squadron, third Skyhawk unit, formed at Tengah Air Base.

Sept 19, 1986: New Skyhawk variant, the A-4U, makes its first flight using General Electric F404 turbofan engine.

1987: Mindef upgrades A-4U again, this time with new avionics, or aircraft electronics.

1989: New-engine Skyhawks enter service with 143 Squadron. 142 Squadron soon follows.

Aug 9, 1990: 142 Squadron and 145 Squadron form the number "25" at National Day Parade with a formation of 25 A-4U Skyhawks.

1997: 143 Squadron retires its Super Skyhawks.

1998: Ten A-4SU Super Skyhawk sent to RSAF training squadrons in France by cargo ship. Another eight Skyhawks shipped in March 1999.

2003: 145 Squadron retires its Super Skyhawks.

March 31, 2005: 142 Squadron's Siper Skyhawks retired. Twelve Super Skyhawks make last flight over Singapore. Training squadron in France will continue flying Super Skyhawks for another two to three years.

Four planes down

While the secondhand warplanes may have been much cheaper than buying new aircraft, keeping them flying was not easy. One particular problem was the engine, as the company that made it had closed.

Col Teh recalled: "These 1950s engines weren't very reliable."

They caused what has been called the Skyhawk Crisis. From July to October 1985, the RSAF lost four planes. The pilot of one plane died.

However, with frequent maintanence, the old engines served till 1993.

In the meantime, plans to replace them were put into high gear.

Two engines were considered, but neither had been put in a Skyhawk before and no one knew how the plane would perform with one of these transplants.

It looked workable, however, and the RSAF decided to try te engine used in the United States Navy F/A-18 Hornet fighter. It was a winner.

When a prototype made its first flight with the new engine on Sept 19, 1986, it outran the F-5F chase planes sent to monitor its performance.

The more powerful engine allowed the aircraft to climb faster, accelerate more rapidly and carry more weapons than the A-4S. It also shortened the Skyhawk's take-off by 30 per cent.

Second Warrant Officer Alywin Ong, 44, a flight line warrant, said: "We were so impressed."

The new engines also needed 25 per cent less time to upkeep.