Rescue crews who spent two hours sifting through rubbish at a Sydney tip after a discarded distress beacon was activated have pleaded with the public to dispose of the devices correctly.

Key points: Passing air traffic picked up an emergency beacon's signals in western Sydney

Passing air traffic picked up an emergency beacon's signals in western Sydney When the Westpac rescue chopper arrived, crews realised it was coming from a rubbish dump

When the Westpac rescue chopper arrived, crews realised it was coming from a rubbish dump Officers spent two hours sifting through trash but could not find the device

The Westpac Life Saver Rescue Helicopter was sent up about 1.30pm on Monday after planes arriving into and departing Sydney began to pick up pings from the beacon.

The crew initially searched the Lucas Heights area before tracking the signal towards Rooty Hill.

They then realised it coming from within a tip at Minchinbury.

Officers used a signal homer as they searched for the device, forced to scour through the rubbish.

By 4:00pm they had moved five tonnes of junk but still hadn't found the beacon, chief executive officer Stephen Leahy said.

"I had my rescue crews sifting through household rubbish and even animal carcasses, trying to find this beacon so we could turn it off," he said.

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When they couldn't find the beacon, they worked on ways to isolate its signal.

The Australian Maritime Safety Bureau (AMSA) said discarded beacons did not belong in rubbish bins, describing their incorrect disposal as a "significant problem".

In the 2017-18 financial year, there were 1,150 non-distress activations of beacons and about 75 per cent were caused by mishandling or incorrect disposal, AMSA said.

"Inadvertent activations of distress beacons potentially make vital resources unavailable for use in real emergency situations," the spokesman said.

"It's also another reason why registering your beacon with AMSA and keeping your details up to date is so important.

"If your beacon has been inadvertently activated and it's registered, search and rescue officers can make contact with you directly to confirm your safety without the need to send vital resources to investigate the signal."

Mr Leahy said while more and more people were using distress beacons for activities such as bushwalking and boating, many didn't realise that throwing them in the bin isn't how they should be discarded.

"When they're crushed, or even when the battery goes really flat, they self-activate," he said.

"In this case, it was an unregistered beacon. It had just been discarded. This made it really difficult."

To correctly dispose of a beacon, users should contact a battery store to first check whether they need to disconnect the power.

Local maritime safety agencies or police can then help with disposal, however manufacturer's instructions can also provide advice on safely getting rid of the devices.