Air New Zealand is a supplier to New Zealand's America's Cup arch-rivals Oracle.
The airline is listed on the United States yachting syndicate's website as a supplier with 28 other companies, some of them international firms but most from America.
Emirates Team New Zealand are on course to race Oracle for the Auld Mug and support for a rival outfit by the airline - which is mainly taxpayer-owned - is puzzling an avid fan of New Zealand's challenge.
"It's strange to think that the national carrier of New Zealand is helping the competition, let alone the New Zealand Government holding a majority stake in the company," said supporter Kurt Bennett.
"I would've thought they would at least support their own."