Any time there’s something of value, that’s transferable, a market is going to try to develop where the person with at least de facto rights earns money and the person who values it the most will pay.

Often the markets develop are deplorable or quite sad, like people selling burned out light bulbs in the Soviet Union or UN aid workers selling emergency supplies to locals after a natural disaster.

At most airlines scheduling is done based on seniority according to a union contract. In addition to making more money per hour and per trip, the best trips go to the people who have worked the longest. Those trips have value and it shouldn’t surprise anyone to see flight crew re-selling their duty assignments.

American Airlines has been trying to stomp out the practice. Flight attendants can rent out their seniority for $200 a trip, selling better schedules to junior crewmembers.

Mid-career flight attendants hate the practice, figuring that if senior flight attendants don’t want to fly the trips they should go to whomever is next in seniority — them — for free. But why shouldn’t the person who values the trip most get it and pay for it?

Now there are allegations that at Emirates there’s less of a black market and something more like UN peacekeepers selling scarce resources: schedulers themselves selling duty assignments to flight attendants, in this case taking money and favors in exchange for not scheduling crew to work very much.

[O]ccasionally human staff do have to get involved and cabin crew who build relationships with scheduling department staffers can benefit massively from these friendships. …So, an allegation of shenanigans in Emirates’ cabin crew scheduling department isn’t all that surprising but the extent to which it went has caused a big ruckus at the Dubai-based airline. According to an anonymous source within the airline, the situation has got so out of hand that when the carrier’s internal security team recently got involved, over half of the department were fired immediately.

The source describes the rostering department as having “basically imploded” and says “people were taking money from staff for favourable rosters, selling leave, giving leave to friends”. Shockingly, the source also alleges that some crew were “using sexual favors to be kept on light rosters”.

I have no first hand information about whether the charges are accurate, but it wouldn’t be surprising.
Rather than a market developing to sell your own property rights in a trip (as at American) this is more of a principal-agent problem. The allegation is that Emirates is allowing employees to use the discretion they’re given as part of the job for personal gain rather than to benefit the company.

Update: Emirates shares the following statement denying the allegations,

The reports on crew buying better rosters are untrue. Emirates flies to over 150 destinations and has a clear and unbiased system when it comes to rostering for cabin crew. There is flexibility in the rosters and crew can bid or swap for preferred flights, however this is practiced with a strict non-remuneration policy.