IT'S a UFO! It's a top secret mission! No, it was just commercial planes waiting to land at Brisbane Airport.

Ipswich residents were treated to the spectacular sight of well-formed "contrails" - condensation trails left behind aircraft - Tuesday afternoon.

The white trails formed just after 5pm, and became more impressive as the sun set.

Many people shared images of the trails online, and turned to forums such as Reddit Brisbane to discuss the cause of the trails.

One Redditor suggested C-17s from the RAAF Base at Amberley caused the contrails, and another user linked them to the "chem-trails" conspiracy theory.

However, many others users correctly assumed the planes were commercial carriers waiting to land at the Brisbane Airport.

An Airservices Australia spokesman confirmed commercial flights were the cause of the trails.

"These are condensation trails produced by commercial flights involved in a holding pattern and waiting for further clearance to descend and land at Brisbane Airport," he said.

A Brisbane Airport Corporation spokeswoman said weather conditions helped to make the trails more visible.

Australian Defence Force spokesman Paul Lineham said the flights were not Defence-related.



Goodna club backs moves to bring back essential footy

premium_icon Goodna club backs moves to bring back essential footy

Proud regional club keen to get juniors going as search for a fourth senior team...

Ambulances rush to Lockyer Valley multi-vehicle rollover

premium_icon Ambulances rush to Lockyer Valley multi-vehicle rollover

Paramedics are assessing patients at the scene of a horror crash.