A converted Boeing 747 owned by Global Supertanker Services makes a demonstration water drop at Colorado Springs Airport in Colorado Springs, in 2016.

AP Photo

The nation's largest firefighting plane has been cleared to fly.

The Forest Service has signed a temporary agreement with the owners of the so-called SuperTanker, a retrofitted 747 based in Colorado Springs.

The jet holds twice as much water or fire retardant as the next largest firefighting aircraft. The FAA approved the SuperTanker to operate last fall, but a lack of agreement with the Forest Service has kept it grounded until now.

Statement From Forest Service Spokesman Ken Palmrose:

"The Interagency Airtanker Board (IAB) gave interim approval to Global Supertanker (GST) LLC. The interim approval is for 17 months during which time GST must take steps to ensure its 747 aircraft delivers retardant in a manner that is effective and efficient and aids firefighting efforts on the ground.

Under certain circumstances, limited contractual options for VLATs are also available to the Forest Service and various states that maintain agreements with the agency. These certain circumstances could potentially include the severe wildfire situations in California and Colorado.

On July 18, the Forest Service posted its intent to solicit for Very Large Airtankers. We are working aggressively to formally announce a Request for Proposals.

To fly wildfire suppression missions on National Forest land, airtankers must have Interagency Airtanker Board interim or full approval, comply with contract requirements including airworthiness and effective delivery of fire retardant and efficient operations."

This story will be updated.