Two international Qantas flights have been forced to return to Sydney Airport on Friday after experiencing mechanical and engineering issues that have affected the planes.
QF7 between Sydney and Dallas has been forced to dump fuel out over the ocean and circled off the coast of Sydney after parts of the A380 aircraft's wings were not functioning correctly.
The flight landed safely at around 4:40pm AEST after flying into Sydney Airport from the south to a host of emergency vehicles awaiting its arrival.
"Qantas flight QF7 from Sydney to Dallas is returning to Sydney due to a mechanical issue," an earlier statement released by the national flight carrier said.
"The flaps on the aircraft (which are attached to the wing) are unable to retract which means the aircraft can't fly efficiently.
"As the Dallas flight is our longest on the network, the captain made the decision to return to Sydney. The aircraft -- an Airbus A380 -- is expected to land at around 4pm Sydney time where it will be inspected by engineers."
QF7 Sydney to Dallas (DFW) is Qantas' longest non-stop route (even longer than Sydney-Dubai) so the aircraft would have been fully fuelled for the 15-hour flight.
As an aircraft's maximum take-off weight (MTOW) exceeds it's landing weight (because of the pressure on the undercarriage on touchdown) the A380 -- the world's largest and heaviest passenger plane -- would have to dump lots of fuel to bring it down to a safe landing weight, hence the circling offshore.
A second flight, QF63 from Johannesburg to Sydney was also safely grounded on Friday due to a cracked windscreen on the Boeing 747-400.
"Qantas flight QF 63 from Johannesburg to Sydney also needed to return to Sydney due to a cracked pane of glass on the aircraft windscreen," Qantas said.
"An aircraft windscreen is made up of three layers of glass, the outer pane had cracked but did not compromise the integrity of the aircraft.
"The aircraft was safe to continue to Johannesburg but the captain made the decision to return as the windscreen will be replaced at Qantas' engineering base in Sydney."
According to the flight's tracked path, the plane managed to fly southwards to Tasmania before needing to circle around and return to Sydney Airport for the issues to be addressed.
The issues come as the latest in a series of technical difficulties for Qantas flights this year after a Melbourne-bound flight from Los Angeles in May was also forced to turn back mid-trip after an engine failed and was reportedly seen sparking.
Further to this, in April 15 people suffered minor injuries when Qantas flight QF29 between Melbourne and Hong Kong came close to stalling mid-flight amid reported 'airframe buffeting' and a 'stick shaker' warning.
The incident lasted just two minutes and caused 'unexpected inflight turbulence', however Qantas launched an internal investigation into the matter.