Climbs sought by plane travellers? (8)

I believe the answer is:

upgrades

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'climbs' is the definition.
('upgrade' can be a synonym of 'climb')

I don't understand the remainder of the clue.

(Other definitions for upgrades that I've seen before include "Increases status or improves quality" , "improvements to software" , "Promotions" .)

I've seen this clue in the Sydney Morning Herald.

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