Footage obtained by the Transport Workers Union shows bed rolls and bedding, hidden behind a baggage carousel laid out on a grubby concrete floor in what has been described as "Third World conditions".

Workers who sleep here are employed by one of Australia's largest aviation services companies, Aerocare, which offers baggage handling, aircraft loading, towing and other aviation services for some of Australia's biggest airlines including Qantas and Jetstar, Virgin and Singapore Airlines.

The Transport Workers Union says workers are spending more than 14 hours per day at the airport, under a split-shift arrangement aimed at cutting costs.

Under the system workers can be told to work more than one shift in a single day. One former worker, Jason, said sometimes there was a six-hour wait between shifts.

"The employees, on their split shifts, just made little nests with airline blankets and waited," he said

"All the other staff know that's where Aerocare go on their shifts. Really you shouldn't even be at the airport after your shift."

Split shifts are allowed under a 2012 agreement that unions challenged.

Fair Work Commission vice-president Graeme Watson approved the enterprise agreement in February 2013, saying it passed the so-called better-off overall test. The test ensures workers are better off overall under a proposed enterprise agreement than they would be under the relevant award.

A former partner at law firm Freehills, Mr Watson was the last remaining Coalition appointee in a senior role at the commission and a strong dissenter in favour of business. He said the commission was "partisan, dysfunctional and divided" when he announced his resignation from it in January.

In his decision, Mr Watson said the minimum three-hour shifts under the Aerocare enterprise agreement was a "disadvantage" to workers compared to the minimum four-hour shifts required under the award.

"I do not believe that a three-hour work period followed by a subsequent one-hour unpaid meal break is consistent with the award requirement that employers roster part-time employees for a minimum of four consecutive hours on any shift or the minimum payment of four hours for casuals," he said.

"I propose to consider this change as a detriment to both part-time and casual employees."

However, considering all the circumstances, Mr Watson said he was satisfied the advantages within the enterprise agreement outweighed the disadvantages.

"In my view the benefits of the agreement are substantial," he said.

However, Jason said Aerocare workers were being paid so poorly they "didn't care about their jobs" and safety standards had started to suffer.

"The pay and conditions were pretty bad, but my main issue was the safety issue, the fact that people are being so poorly remunerated they don't care about their jobs," he said.

"They are budget providers and this is not an industry that you should employ people on a budget."

TWU national secretary Tony Sheldon said the footage showed "the reality of work behind the shiny facade of our airports".

"Workers are struggling on slave wages and sleeping on bed rolls because they have to spend long days at work to support their families," he said.

"This is being allowed to happen because airports and airlines are outsourcing work to low-cost companies and not giving a damn about the workers in their supply chains that it affects."

In February, Qantas posted a statutory net profit after tax of $515 million, down 25 per cent on the previous year's result.

Aerocare said it was negotiating a new workplace agreement.

Chief executive Glenn Rutherford said he was focused on improving its rostering system and securing more contracts to help employees get longer shifts.

"It obviously isn't our preference to have shorter shifts but rostering is driven by the needs of our customers, with rosters determined by flight schedules and noting that it generally takes three hours to fully service an international aircraft," he said.

But any suggestion its employees were being "forced" to camp out in secure areas of Sydney airport while they wait for their "split shifts" was "false".

"No Aerocare employee is forced to do anything and it is difficult to comprehend how anyone could make such a claim given that last year alone we had over 180 safety and security related audits - all of which were passed," Mr Rutherford said.

"We would never knowingly allow any of our employees to sleep at the airport as the safety and well-being of our employees is paramount to our operation.

"Our employees enjoy improving wages, and safer conditions than those offered by many of our competitors and we have spent millions of dollars improving our rostering system to maximise the duration of employee shifts."

A Sydney Airport spokeswoman said it worked closely with airport partners, including the AFP and Border Force, to ensure a safe and secure environment.

"Any matters raised at the airport are resolved in consultation with our partners, in accordance with the relevant legislation," she said.

Jetstar, which is owned by Qantas, said the union claims were part of negotiations for a new pay deal between Aerocare and their employees and was "a matter between them".

"Aerocare's airline customers like Jetstar do not determine the pay and conditions of Aerocare's employees," the spokesman said.

"Aerocare has advised us that their employees are not required to work multiple shifts in a day."

Aerocare supplies aviation services to Jetstar, QantasLink and other Australian and international airlines at airports around the country.