
Issued by the aviation regulatory authority in the country where the carrier is based, the Air Operator's Certificate (AOC) is the primary certificate that an airline needs to start selling flights to customers.
It is granted once the airline proves it has the necessary aircraft, staff, safety systems, and financial resources to operate over the long term.
A lack of liquid cash to remain operational is the most common reason an airline has its AOC revoked.
Airlines that saw this happen over the last six months include Estonia-based SmartLynx Airlines, Austria's Mali Air, and Swedish charter carrier H-Bird.
In the U.S., Houston-based charter carrier Starflite Aviation also lost its AOC after the FAA alleged that the airline falsified pilot training records to bypass various safety checks.
The latest airline to lose its AOC, as first reported by Swiss outlet ch-aviation, is Malta-based LEAF. Short for Lease and Fly, the subsidiary of the Portuguese wet lease airline Hi Fly received the certificate in May 2025.
The parent company gave the new venture an Airbus A340-300, aiming to launch charter flights to the Mediterranean island nation from nearby European capitals. A wet lease allows a company with a larger fleet to provide the airline, crew, and insurance for an airline that lacks its own.
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LEAF is a "next-generation airline delivering innovative, sustainable Wet Lease and Charter solutions," it writes on its LinkedIn page, where it also says it employs between 51 and 200 staff. "With a global reach and an all-Airbus widebody fleet, we empower partners with flexible, efficient air transport backed by top-tier safety, reliability, and environmental responsibility."
Hi Fly is headquartered in Lisbon and is itself a wet lease airline providing other airlines with aircraft in different parts of the world. Although few details about the reasons for LEAF's lost AOC are currently public, many airlines that lose AOCs struggle to run flights.
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Any flights that LEAF may have been scheduled to fly are now canceled. In March 2026, Slovenian charter airline AlpAvia also lost its AOC due to financial problems as it struggled with the business model of selling wealthy customers charter flights to cities such as Vienna, Valencia, and Lyon.
New York-based charter airline Tailwind Air also tried to run downtown-to-downtown routes between New York, Boston, and several other East Coast cities but ultimately filed for Chapter 11 protection in January 2026 when it failed to bring in enough passengers.
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