“The world’s first purchase agreement for net-zero carbon supersonic aircraft marks a significant step toward our mission to create a more accessible world,” said Boom CEO Blake Scholl in a statement.

The planes, which will fly twice the speed of current passenger jets, are expected to be rolled out in 2025, take flight in 2026, and start carrying passengers in 2029.

Since Denver-based Boom was founded in 2014 it has raised $270m in capital and now has 150 employees.