The pair picked up Landmark from Dubai Aerospace five years ago and have hired Morgan Stanley to advise on the sale, according to Reuters.
It said the auction was already in the second round and that private equity and infrastructure firms have expressed an interest.
In May GTCR paid between $600m and $700m for private jet maintenance-tracking services company CAMP Systems from buyout house Warburg Pincus.
GTCR was understood to be one of at least five private equity bidders for the business including Bain Capital and Welsh, Carson, Anderson & Stowe.
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