Whilst OJA might be just another aeroplane to many, there are good reasons why we are excited about being able to put her on display.

The "400" series of the 747 caused an advance in world airline travel that was in its own way just as significant as the introduction of the 707 that introduced the jet age and original 747 which ushered in new benchmarks for passenger carrying capacity and aircraft safety.

Many of us here at HARS have either flown or maintained her during our careers.

In the mid-1980s the predominant model of the 747 that resided in Qantas was the Pratt & Whitney powered 747-200.

With a 352-tonne take-off weight, it could fly a planeload of passengers about 5000 nautical miles - that is the distance from Singapore to Athens. How do I know? I had a couple of interesting sectors proving that there wasn't much more range in the aeroplane than that, doing just that.

At that time, flying to London involved stopovers at Singapore and Bahrain and crews could be away from home for up to two weeks. Routes across the Pacific were not much better, with either one or two stops at Los Angeles and San Francisco.

There was a glimmer of Ultra-Long Haul with the two SP 747s flying - their Rolls Royce engines gave them the range to fly Los Angeles and San Francisco direct to Sydney (6600 nautical miles) with a reduced passenger load of just 222, mainly first and business class.

When Boeing announced the development of the 400 it was a really advanced machine, building upon the tried and true 747 airframe and systems engineering and taking the "Glass Cockpit" a further step forward from the 767 with all computer screen instruments and the elimination of the flight engineer who was replaced by sophisticated computer-monitoring sensors and more automation.

Further inclusions were carbon brakes, another 20-tonne weight increase to about 395 tonnes, 10 tonnes of fuel in the tail's horizontal stabiliser and more powerful, efficient engines (pushing range out to over a healthy 7000 nautical miles).

Qantas became one of the three launch customers with an order of 18. It was a gamble because it increased the company's debt, however it was felt that Qantas could not afford to be without this machine.

We all know of the "cunning plan" hatched by Captain Dave Massy-Greene and Flight Operations to show off the range capabilities of the aircraft - London to Sydney was pretty impressive, though today we could do that in the A380 without all the trickery needed back then.

Of course aviation has always been this way - what was a tight, hard-worked exercise then is today routine. Consider Qantas' finest long-haul flying adventure of those "double-sunrise" flights using the Catalina flying boat during World War II.

Whilst the 400 did ad-hoc commercial flying initially, it had to wait for the first three to be delivered to start a dedicated service, which started at the end of October 1989. Deliveries were: VH-OJA August 17, VH-OJB September 2, VH-OJC October 15.

The first "All 400 Service" was started by OJC on October 29 - I was on the crew from Singapore to London - 14 hours 30 minutes all night.

This is where it all gets interesting. In that one sector we covered what would have needed two sectors before and the gain in crew efficiency by the airline was dramatic.

What would have needed three crews and three days of their time was now done overnight.

The introduction of the 747-400 saw a whole swag of new single-sector flying that previously would not have been possible, needing intermediate stops.

Crew efficiency dramatically improved as trip time away from home dropped.

Yes, OJA is a significant aircraft in aviation history, representing a new generation providing a big jump in both performance and technology in airline operations. If we don't stop and preserve such examples, they will all be gone and we will be the poorer.