FlightAware Sues Kalshi Over Flight Data

FlightAware sued four Kalshi entities in Manhattan federal court on Aug. 10, alleging the prediction-market operator used restricted flight-cancellation data and its trademark without authorization. The 45-page complaint says Kalshi used FlightAware data to decide whether contracts won or lost.

The filing names Kalshi Inc., KalshiEX LLC, Kalshi Klear Inc., and Kalshi Klear LLC as defendants. It alleges Kalshi certified markets using FlightAware data as early as July 2022 and offered flight-cancellation markets on its website from at least April 2026.

The complaint describes two types of contracts. Airport-specific markets asked whether the share of scheduled cancellations at a named airport would cross a set level. Separate nationwide markets used weekly U.S. cancellation totals.

The complaint and API materials reviewed describe aggregate outcomes, not contracts on whether a single named flight will be canceled.

How Does FlightAware Say Kalshi Used Its Data?

FlightAware says Kalshi held a Personal AeroAPI account under terms barring commercial use. FlightAware amended its terms on July 16 to prohibit using its data for betting, prediction markets, and event contracts.

“Kalshi’s market rules designate FlightAware’s classifications and data as the facts that determine whether a wager wins or loses,” the complaint says.

The complaint also says Kalshi identified the U.S. Department of Transportation's Bureau of Transportation Statistics as an alternative source if FlightAware data became unavailable.

According to FlightAware, it revoked the account and sent a cease-and-desist letter on July 15. The complaint says Kalshi denied violating the license or trademark two days later and argued that its references to FlightAware were nominative fair use. FlightAware says Kalshi then added a disclaimer stating that it had not endorsed the markets.

What Happens to Kalshi's Active Markets?

Kalshi's public API returned 10 active nationwide flight-cancellation markets for the week ending Aug. 14 when checked at 4:55 p.m. UTC on Aug. 11. The contracts asked whether U.S. cancellations would exceed totals from 1,000 to 10,000.

The API still named FlightAware's weekly cancellation page as the settlement source. It said Kalshi would use the total shown there at 5 p.m. EDT on Aug. 14, while its disclaimer said the source agency had not endorsed the markets.

FlightAware requests a temporary restraining order, preliminary and permanent injunctions, damages, an accounting of Kalshi's profits, and a jury trial. Its six counts include breach of contract, federal trademark infringement, injury to business reputation, unjust enrichment, and federal and New York unfair competition.

No current Kalshi response or defense filing was located through the public sources checked on Aug. 11. The complaint's claims and its account of Kalshi's earlier position are allegations, not court findings.

For traders, the contracts have not been ruled invalid. The immediate question is whether Kalshi can continue using FlightAware as the named settlement source or must rely on an alternative. The case is separate from New York's state action against Kalshi, which FairGambling covered on July 31.