Nexus, the public body which owns and manages Metro, said the airport line was one of the more important projects in the history of the Metro service.
The £12million scheme, opened on November 17, 1991, provides one of the fastest airport to city centre transfers in the country.
Millions of holidaymakers and business travellers have benefited from it over the years as the airport itself has grown.
Metro operations director John Alexander said: “Extending the Metro system to the airport created a vital strategic link for North East England.
"It was one of the most crucial developments of the network in its history, and it has been a real success story for us.
“The airport has grown massively since 1991 and Metro customer numbers have reflected that.
"We’re proud to be part of that growth story.
“It was a vital shot in the arm for the local economy, and for the growth and profile of Newcastle International Airport itself.”
Graeme Mason, planning and corporate affairs director at Newcastle International Airport, said: “As the North East’s largest Airport we are fortunate to benefit from excellent surface access links for our passengers to use.
"The Metro plays a vital role in providing convenient connectivity between the Airport, Newcastle city centre and beyond and we are delighted to celebrate the 30th anniversary of the partnership this month.”
Construction of the airport line began in 1990 after funding had been secured from the EEC, what we now know today as the European Union.
It was the first extension of Metro since the line to South Shields opened in 1984.
New track, 3.5 kilometres in total, was built across the fields behind Woolsington village, extending Metro beyond the Bank Foot terminus.
An entirely new station, with its unique pyramid design, was constructed next to the airport terminal, with a walkway connecting the platforms to the main building.
It also saw the construction of Callerton Parkway Metro station, which has become a popular park and ride site. A second platform was built at Bank Foot.
The airport station was purposely built into a cutting to ensure that Metro’s overhead lines and signalling equipment were kept well below the flight path.
One of the challenges for Nexus staff is maintaining the western end of the line beyond Bank Foot station, especially in winter. The higher elevation of the railway often leads to heavier snow falls which, due to the open countryside, can lead to windblown drifts during bad winters.
Retired Metro driver Michael Bushby had the job of taking the first passengers to Newcastle Airport in 1991.
He said: “I remember the airport extension opening back in 1991 because it was quite an exciting project and somewhere new to drive the trains.
"There are lots of things on the airport route that you don’t get anywhere else on the network – not least the special trip wires in case of low flying planes.”