Qantas passengers have described their experience on board after one of the engines failed mid-air during a flight from Auckland to Sydney.

Firefighters and paramedics were on standby at Sydney airport after a mayday call was issued by flight QF144 about 4.10pm today NZ time.

The alert was later downgraded to a PAN, which means possible assistance needed.

“It was a little bit bumpy but it was just like turbulence," said traveller Leslie Spring. Photo / NCA NewsWire

Passenger Nigel Morris said: “We didn’t know anything at the time but we’re here safe.

 “When they said we could turn on our phones, I turned on my phone and my wife had called about 18 times.

“It’s a debate about whether it’s better to know or not to know.”

Aerial footage showed the plane as it descended into the airport before landing on the tarmac, in Mascot, in Sydney’s eastern suburbs.

One woman, who was visiting from the UK via New Zealand, told NCA NewsWire the pilot communicated with passengers about an “engine problem” but not that they had issued a mayday call.

• Mayday call: Passengers recall 'large bang' on Auckland-Sydney flight

The flight was scheduled to land at 5.10pm but it landed safely at 5.26pm, according to FlightRadar24.

Its departure from Auckland Airport was delayed by 55 minutes.

Qantas flight QF144 from Auckland to Sydney lands safely after reported engine failure. Photo / Supplied, 9News

Other travellers said they heard a “bang” and a “few gasps” upon landing.

One couple told the NewsWire: “We didn’t realise the whole engine had gone, we just heard a bang and that was it.

“There were a few gasps when they told us on the actual runway, but we had already landed.”

Another passenger Leslie Spring said: “It was a little bit bumpy but it was just like turbulence, if they hadn’t told us we wouldn’t have known.”

The jet, a Boeing 737-838, has twin engines but can fly on just one.

A Qantas spokesman said: “Qantas Flight 144, a 737 flying from Auckland to Sydney, experienced an issue with one of its engines about an hour from its destination.

They said the aircraft landed safely and is now being inspected by engineers.

“The 145 passengers onboard disembarked the aircraft normally. While inflight engine shutdowns are rare, and would naturally be concerning for passengers, our pilots are trained to manage them safely and aircraft are designed to fly for an extended period on one engine.”