ARNOLD AIR FORCE BASE, Tenn. -- With the passing of the unit guidon, leadership of the 717th Test Squadron officially transitioned from Lt. Col Joshua Thomas to Lt. Col Jonathan Tellefsen during the Change of Command ceremony held on June 9, 2026, at Arnold Air Force Base, Tennessee.
Upon assuming command, Tellefsen thanked the leaders who entrusted him with the opportunity and recognized the leadership of his predecessor.
“Teddy [Thomas], your leadership has been exceptional. I could not be taking over from someone more capable or someone who has led this squadron exactly as it needed to be led,” Tellefsen said to Thomas. “Thank you for everything you have done for this team.”
The 717 TS tests the powerhouses of aircraft and missiles, delivering actionable data to decision-makers and supporting the development and sustainment of critical warfighting capabilities. The test squadron is made up of a suite of test cells across Arnold AFB that support test and evaluations of performance, operability, aeromechanical, icing, corrosion, inlet pressure distortion, accelerated mission testing, engine-inlet dynamics, mission simulations and engine component testing.
Prior to assuming command, Tellefsen served as Director of Operations for the 715th Test Squadron, AEDC, where he led day-to-day operations for the 191-member squadron. Under his leadership, the unit executed ground tests in the nation’s largest and most complex hypersonic propulsion test cell and $190M arc jet test facilities. He also coordinated real-time resource deconfliction among six organizations across the AEDC campus.
Reflecting on the experience he brings to the position, Tellefsen said his previous assignments have prepared him to lead the squadron’s critical test mission.
“To the members of the 717th TS, I am excited to serve in this new role,” said Tellefsen. “I am humbled by the work you do every day and by the impact this organization has on our Air Force. While I bring my own experiences to the position, I know I have much to learn from each of you.”
Tellefsen was commissioned through the U.S. Air Force Academy in 2010 with a Bachelor’s degree in Aeronautical Engineering.
Throughout his career, he has served in numerous developmental and operational test assignments across both ground and flight test units. As a flight test engineer, he accumulated more than 307 flight hours while testing C-130, F-15, and F-16 aircraft.
He also served as an instructor of Aeronautics at the U.S. Air Force Academy. While deployed, he served as Duty Officer for the Bahrain Air Defense Liaison Team during Operation Epic Fury, where he provided critical integration with Bahraini air defenders to prevent fratricide of U.S. forces during an operation that flew more than 10, 000 sorties.
Looking ahead, Tellefsen highlighted his commitment to supporting the squadron’s workforce and mission.
“As I reflected on the mission of the 717th Test Squadron, my thoughts returned to Operation Epic Fury and the more than 10,000 sorties flown during that operation,” expressed Tellefsen. “Not a single aircraft was lost due to an engine issue. That success is a testament to the professional, expertise, and dedication of people like those serving in this squadron today. It is an honor to serve alongside you as we help power the world’s greatest Air Force.”