FAA also issued a general warning on Thursday about BlackBird and any other organizations that make chartering a flight "as easy as tapping a few buttons on your mobile device."
"The letter [to BlackBird] emphasizes an FAA policy about the requirements for pilots who are paid to fly passengers," FAA wrote. "The policy states that pilots who are paid to fly passengers generally can't just hold the required Commercial or Airline Transport pilot license – they also must be employed by the company operating the flight, which must hold a certificate issued under Part 119 of the Federal Aviation Regulations. Or the pilots must themselves hold a Part 119 certificate."
BlackBird has maintained that it is an online platform, not an air transportation provider, and doesn't need to meet such requirements.
The company was backed with $10 million from venture capital firm New Enterprise Associates.
Uber itself offers helicopter rides, a relatively new development this year. An eight-minute Uber helicopter ride from Manhattan to JFK International Airport was briefly cheaper than an Uber Black car for a small, select group of users in early November.
FOX Business' inquiry to BlackBird was not immediately returned.