During the Australian winter months, while many crave a little extra morning sleep-in – three international airlines are being allowed to land passenger jets every day of the week in the hour before the curfew is lifted.

The airlines getting the favourable treatment, Qantas, British Airways and Singapore Airlines are allowed to land between 5am and 6am, the so-called shoulder period – because of the northern hemisphere summer and the curfews at airports including Heathrow – even though those aircraft stop at other airports en route to Sydney.

Twenty-one flights a week will be landing before 6am until October – and residents in the surrounding area fear there is a push by airline operators to allow more aircraft to take advantage of the 5am to 6am shoulder time slot.

It used to be four flights a morning before 6am but when one airline cancelled its service coming from Frankfurt, the former federal infrastructure minister Anthony Albanese refused to let the landing spot be approved or transferred to another flight.

A spokesman for Infrastructure Minister Warren Truss said that Section 12 of the Sydney Airport Curfew Act 1995 allows for up to 35 weekly international arrivals during the morning curfew shoulder period. But he said "noise respite for residents is protected by the legislated requirement that all arrivals must use runway 34L – approaching the airport over water from the south.

Kevin Hill, the south representative on the Sydney Airport Community Forum told The Sun-Herald "we don't want any more changes that will add aircraft movements to the curfew period".

Mr Hill said that the airport is busy enough, especially during the curfew hours.

"There is a perception that the there is no noise during the curfew hours and that the airport shuts down," said Mr Hill who lives in a suburb neighbouring the airport.

"But walk outside at 3am and you will hear all the planes coming and going. There are flights all night long," he said.

Statistics published by AirServices Australia show that the busiest times at night for aircraft during the curfew (11pm till 6am) are between 11pm and midnight and between 3am and 4am.

In the past year there have also been 3219 arrivals and departures from Sydney Airport during the curfew hours – an average of about nine every night. That is down slightly from the 2013 figures which show 3422 arrivals and departures during curfew hours. There have also been 1213 complaints made in the 2014 year about noise from Sydney Airport. The number of complaints was down from 1564 complaints made in 2013.

In the past year there have been 35 requests by passenger airlines to take off or land outside their scheduled time and during the curfew period. Of those 19 were refused and 16 approved.

The 3219 movements that are also "allowed" during the curfew are the arrival and departure of freighter planes and private business jets plus medical emergencies. The federal government has already announced it has allowed more private jets to use the airport during the curfew hours, but only the new, quieter ones.

A statement from Mr Truss said the changes will allow quieter, more efficient aircraft to land during the nightly curfew. However, the older noisier aircraft that have been using the airport during curfew hours will continue to be able to take off and land during the curfew until 2022, when they will be banned.

Allan Rees, of the No Airport Noise party, said the party has always been worried about "curfew creep".

The 5am shoulder period was agreed to years ago when councils and residents were promised it would be only temporary because another airport was to be built at Badgerys Creek, and that would prevent the need for the building of a third runway, he said.

The curfew act never intended for Sydney Airport to be a 24-hour operation, Mr Rees said.

The No Airport Noise party made submissions to the federal government to stop the "private and business charters" during curfew hours saying the "rights of Sydney residents to a decent night's sleep outweighs the privilege of allowing commercial flights through the curfew".

The party also asked for the shoulder period of international arrivals from 5am to 6 am operating over Botany Bay to be stopped.

They also want the ground running and testing of aircraft engines during the curfew period stopped.