Jet chases passenger plane across Sydney skies

Sydney CBD office workers who glanced out the window at faced something straight out of Hollywood - a low-flying large passenger plane being chased across the harbour by a fighter jet.

Phillipa Kelly, who works at a financial services company near Circular Quay, said the noise of the planes stopped work at her office on Monday.

"It came very close to the building and we all stopped and said: 'Oh my God! What was that noise?'.

"We're in the first block back from Circular Quay ... and there's this big passenger plane that has come very close to our building, and it has a fighter plane following it.

"The [passenger] plane had a massive plume of smoke and was losing altitude really quickly."

Ms Kelly said the planes flew out towards Mosman, but returned a short time later, before disappearing again.

Steven Gunther saw the plane pass the AMP building, and exited his building.

"I watched it fly north over Mosman and then bank out over the coast and head back towards the city.

"It was at this point that I told my colleagues I was getting out of the building and it seems I wasn't the only one with the same idea. There were some scared and bewildered people on the streets and I was one of them.''

Suzie Brook, who saw the planes from the 28th floor of her office building in the Martin Place, described it as terrifying.

"It would have been nice to know that this incident was planned ... rather than look out your window and see a low flying passenger plane heading straight for your building,'' she said.

"It was terrifying."

Fortunately, the incident was not an air force pursuit of a hijacked passenger flight, but a "farewell flight" for the defence force's Boeing 707 aircraft.

The aircraft was being retired from service after 29 years, the department said.

About 11am (1pm NZT), the B707 aircraft made its farewell flight, accompanied by a Hawk 127 lead-in fighter aircraft from which photos of the flight were taken, the department said.

Office workers in the CBD had no cause for alarm, said Defence spokeswoman Raveena Carroll-Kenney.

"I can confirm the aircraft has landed at the RAAF base in Richmond, and it was a great flight."

But some smh.com.au readers expressed their frustration that the public had not been informed about the flight.

Gunther wrote in an email to smh.com.au: "To think that seeing a Boeing 707 being tailed by a fighter jet flying at low altitude over the CBD, watch it turn around and head back towards the city wasn't going to cause concern is deplorable.

"In this age of terrorism the defence force of all people/organisations should have known better.

"I have never felt quite so scared. If a plane is ever hijacked and flown towards the city, how many people will look out of their high rise office building and comment on another defence force joy flight for a retiring aircraft?"