Etihad Airways has agreed to buy three pairs of slots at London Heathrow airport from Indian carrier Jet Airways for $70 million.
Jet Airways will continue to operate the slots under a sale and leaseback agreement signed on 26 February.
Secondary slot trading is commonplace at Heathrow due to limited runway space at the airport, which operates at 99.2% capacity.
The sale gives Etihad future growth potential at the UK hub while also freeing up cash reserves for Jet Airways.
Separately, the two airlines are in due diligence proceedings over a prospective sale of 24% of Jet Airways to Abu Dhabi's flag carrier.
That deal was expected to have been concluded earlier in February, but Reuters subsequently reported that Etihad is revising its planned agreement.
The proposed equity sale came after India's government relaxed foreign direct investment rules for the country's carriers.