The 30th anniversary of Qantas' record-holding Boeing 747 jumbo jet continuous flight from London to Sydney — a marathon journey featuring specially-made fuel and covert planning — has been marked this weekend.

Key points: The 747 VH-OJA is celebrating the 30th anniversary of its record-breaking London-to-Sydney flight

The 747 VH-OJA is celebrating the 30th anniversary of its record-breaking London-to-Sydney flight The flight required top-secret planning and special fuel to increase the plane's range

The flight required top-secret planning and special fuel to increase the plane's range The plane was donated by Qantas to an Illawarra aviation museum in March 2015

It was an ambitious plan to push a new aeroplane further than it had been pushed before — part publicity stunt, part celebration of how far aviation had advanced.

Qantas pilot David Massy-Greene wanted to fly a 747-400 non-stop from London to Sydney and into the record books, where it remains today.

The year was 1989 and the aircraft, with its distinctive two-level bubble at the front, was fresh on the market.

"We were trying to demonstrate to the travelling public what the differences were with the new aircraft and what its capabilities were," said co-pilot on the London to Sydney trip, Ray Heiniger.

"The main one was the ability to travel long distances comfortably."

Special fuel for special flight

The problem was, a 747 jumbo could not travel from London to Sydney comfortably because it had a range of only 14,800km and the trip was 17,000km.

No matter how Captain Massy-Greene planned to do it, he kept coming up short.

Pilots (L to R) Rob Greenop, David Massy-Greene, Ray Heiniger, and George Lindeman celebrate the flight. ( Supplied: Qantas )

Fortunately, aviation fuel provider Shell liked the ambitious plan and developed a special fuel that would give 4 per cent greater burning power than regular fuel.

"We had to keep it secret because we had a lot of other people who probably would've tried the same adventure if they thought of it," Mr Heiniger said.

"Shell produced this stuff where they had to get batches of fuel in Germany, put it in railway carriages, and shunt it up and down for several days to mix it properly.

"Then it was put in tankers and taken across the (English) Channel to the UK where we fuelled the aircraft for our departure."

The plane was filled with the super-fuel and with just 23 people on board — in a cabin that can hold more than 500 — the plane, known as The City of Canberra, call sign VH-OJA, made its 20 hours, nine minutes, and five seconds flight from London to Sydney.

Former Qantas employee and aviation enthusiast Steve Heesh has written a book about VH-OJA. ( ABC Illawarra: Justin Huntsdale )

Plane becomes a major tourist attraction

With Qantas slowly retiring its fleet of 747-400s, VH-OJA was destined for a US aircraft boneyard.

However, in a coup for the suburb of Albion Park Rail, south of Wollongong, the airline decided to donate the jumbo to the Historical Aircraft Restoration Society (HARS) in 2015 where it now dwarfs all other planes on site.

It is the same museum to which John Travolta has donated his own 707, which is due to arrive later this year with the Hollywood star on board.

"It's drawn huge crowds, as it did on its day of arrival," former Qantas employee and HARS volunteer guide Steve Heesh said.

"It's been the major attraction here and the fact you can see it from the highway is terrific.

"It's parked with the tail overhanging the roadway which gives you an idea of the scale of it and the 747 itself is a remarkable and momentous plane."

The City of Canberra landed for the last time in the Illawarra in March 2015. ( Supplied: Michael Samson )

Aircraft every pilot loved to fly

Mr Heiniger said the City of Canberra not only holds special memories for him, it was a much-loved plane among pilots.

"There's not much you can't like about this lovely old aircraft," he said.

"I like the look of it [and] its abilities, in that it was the first to carry that number of passengers and cover the distances it can fly.

"I was a training director in Qantas and taught people to fly this aircraft and you'd think something this big would be difficult to fly, but every pilot loved it."

Mr Heesh said the 30-year anniversary would be a special day for the plane's many admirers.

"We probably should break a bottle of champagne or two and we hope people will join us to mark the occasion and pay homage to this aeroplane," he said.