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Boom Aircraft Goes Supersonic for the First Time
The historic first supersonic flight of the Boom XB-1 demonstrator aircraft at Mojave.
Summary
This recording captures the communications of Boom Supersonic's XB-1 demonstrator during its first supersonic test flight on January 28, 2025. Operating under the callsign Kestrel 1-1, the aircraft was accompanied by a Mirage and a T-38 chase plane as it utilized the supersonic corridor in the Mojave Desert. The transcript concludes with Mojave Tower and Ground controllers offering their congratulations to the team upon their successful return.
Analysis
This recording documents a significant milestone in modern aviation: the first supersonic flight of the Boom XB-1, a "baby bird" demonstrator for the Overture supersonic airliner. The flight took place at the Mojave Air and Space Port, a legendary site for flight testing. The mission involved a "flight of three," consisting of the XB-1 (Kestrel 1-1) and two high-performance chase planes—a Mirage (Kestrel 1-2) and a T-38 Talon (Kestrel 1-3). Chase planes are essential in flight testing to provide external observations, safety monitoring, and photography of the experimental aircraft.
The technical nature of the flight is highlighted by the request for "Stage 2" operations and access to "Supersonic Corridor 1505." In the Mojave region, test flights are strictly regulated within the R-2508 Complex. "Stage 2" at Mojave typically refers to specific safety and noise protocols for high-performance or experimental departures. The supersonic corridor is one of the few places in the United States where aircraft are legally permitted to break the sound barrier, which requires specific coordination with "Sport" (the callsign for the R-2508 complex's mission control).
The transcript also captures the interest of other pilots in the area. A pilot of a nearby aircraft (405PA) asks the controller if the "Boom aircraft" had taken off, expressing the excitement within the aviation community regarding this project. The controller confirms that the flight of three they are looking at is indeed the Boom team returning from their mission.
The significance of this event cannot be overstated; Boom Supersonic is attempting to revive commercial supersonic travel, which has been dormant since the retirement of the Concorde in 2003. The professional and calm demeanor of the pilots and controllers belies the high-stakes nature of the mission. The recording ends on a high note with Mojave Tower and Ground controllers breaking standard brevity to offer "congratulations," acknowledging the historical weight of the successful Mach-exceeding sortie.
Original ATC Communication
Plain English Translation
KESTREL 1-1
Mojave Ground, good morning. Kestrel 1-1 is a flight of three. We are at Boom, north of Runway 30, with Information [inaudible]. We’re requesting Stage 2, and we'll have one truck following us.
KESTREL 1-1
Mojave Ground, good morning. Kestrel 1-1 is a formation of three planes. We’re over at the Boom hangar, north of the main runway, and we have the latest weather update. We're requesting Stage 2 clearance, and we’ll have a support truck following behind us.
ATC - MOJAVE GROUND
Kestrel 1-1, flight of three, Mojave Ground. Runway 30, taxi via Charlie Alpha.
ATC - MOJAVE GROUND
Kestrel 1-1, group of three, Mojave Ground. Head to Runway 30 using taxiways Charlie and Alpha.
KESTREL 1-1
Charlie Alpha, Kestrel 1-1.
KESTREL 1-1
Taking Charlie and Alpha, Kestrel 1-1.
ATC - MOJAVE GROUND
Kestrel, can you say which aircraft type belongs to which number?
ATC - MOJAVE GROUND
Kestrel, can you tell me which type of aircraft is assigned to each flight number?
KESTREL 1-1
Affirmative. Kestrel 1-1 is XB-1, 1-2 is the Mirage, and 1-3 is the T-38.
KESTREL 1-1
That's right. Kestrel 1-1 is the XB-1, 1-2 is the Mirage, and 1-3 is the T-38.
ATC - MOJAVE GROUND
Kestrel 1-1, Roger. Who is the designated lead, and are you requesting Stage 2?
ATC - MOJAVE GROUND
Kestrel 1-1, copy that. Who is the designated leader for the group, and are you still requesting Stage 2 clearance?
KESTREL 1-1
Lead will be Kestrel 1-1. Kestrel 1-3 will just maintain the comms for simplicity. And I confirm we are requesting Stage 2. We have an Op number for 2515 and Supersonic Corridor 1505.
KESTREL 1-1
Kestrel 1-1 will be the leader, but 1-3 will handle the radio calls to keep things simple. And I confirm we're requesting Stage 2. We have our mission authorization numbers for the test range and the supersonic corridor.
ATC - MOJAVE GROUND
Roger. Contact Mojave Tower. And how are you departing today?
ATC - MOJAVE GROUND
Understood. Switch over to Mojave Tower now. And what is your plan for departure today?
KESTREL 1-1
All three on the runway in five-second intervals.
KESTREL 1-1
All three of us will take off from the runway one by one with five-second gaps between us.
ATC - MOJAVE GROUND
Kestrel 1-1, Roger.
ATC - MOJAVE GROUND
Kestrel 1-1, copy that.
ATC - MOJAVE TOWER
Kestrel 1-1, cleared Stage 2. Squawk 0111 in order.
ATC - MOJAVE TOWER
Kestrel 1-1, you're cleared for Stage 2. Set your radar tracking codes to 0111 and the following numbers in order.
KESTREL 1-1
0111 in order, cleared Stage 2, Kestrel. We request about two minutes on the runway. We’ll be a right turn out.
KESTREL 1-1
Tracking codes 0111 in order, cleared for Stage 2, Kestrel. We'd like to stay on the runway for about two minutes before we go, and we'll be turning right once we're up.
ATC - MOJAVE TOWER
Kestrel 1-1, flight of three, Mojave Tower. Runway 30, line up and wait. Advise when ready.
ATC - MOJAVE TOWER
Kestrel 1-1, group of three, Mojave Tower. Pull onto Runway 30 and hold your position. Let me know when you're ready to go.
KESTREL 1-1
Line up and wait, will advise, Kestrel. Flight will be ready in about 15 seconds.
KESTREL 1-1
Moving onto the runway to wait, we'll let you know, Kestrel. The group will be ready in about 15 seconds.
ATC - MOJAVE TOWER
Kestrel 1-1, flight of three, Runway 30. Wind 240 at 7, cleared for takeoff.
ATC - MOJAVE TOWER
Kestrel 1-1, group of three, on Runway 30. The wind is 7 knots from the southwest, you are cleared for takeoff.
KESTREL 1-1
Cleared for takeoff, 30, Kestrel Flight.
KESTREL 1-1
We’re all set to take off from runway three-zero, the Kestrel group is rolling.
ATC - MOJAVE TOWER
Kestrel 1-1, contact Joshua 133.65. We’ll see you later.
ATC - MOJAVE TOWER
Kestrel 1-1, go ahead and switch over to Joshua Approach on frequency 133.65. Catch you later.
KESTREL 1-1
Switching, flight push.
KESTREL 1-1
Changing frequencies, everyone in the flight switch your radios now.
KESTREL 1-1
Joshua Approach, good morning. Kestrel 1-1 is a flight of three off Mojave, passing 5,300 to join 2515 and the Supersonic Corridor.
KESTREL 1-1
Good morning, Joshua Approach. This is Kestrel 1-1, we’re a group of three planes out of Mojave. We’re climbing through 5,300 feet to enter testing area 2515 and the high-speed corridor.
ATC - JOSHUA APPROACH
Kestrel 1-1, Joshua Approach. Good morning. The altimeter is 30.04. Stay left of the handoff point.
ATC - JOSHUA APPROACH
Kestrel 1-1, Joshua Approach. Good morning. Set your altitude gauges to 30.04. Make sure you stay to the left of the handoff point.
KESTREL 1-1
30.04. And confirmed, cleared to contact Sport for Kestrel Flight?
KESTREL 1-1
Gauges set to 30.04. And just to confirm, is the Kestrel group cleared to talk to 'Sport' mission control now?
ATC - JOSHUA APPROACH
Kestrel 1-1, altimeter 30.04. Stay left of handoff point.
ATC - JOSHUA APPROACH
Kestrel 1-1, keep your altitude gauges at 30.04. Stay to the left of that handoff point.
KESTREL 1-1
30.04, thank you. Standby. Kestrel 1-1 flight, radar service terminated. Contact Sport.
KESTREL 1-1
30.04, thank you. Wait one. Kestrel group, we’re leaving Joshua’s radar coverage. Switch over to Sport control.
KESTREL 1-1
Switching Sport, Kestrel 1-1 flight push.
KESTREL 1-1
Moving to Sport now, Kestrel group switching frequencies.
KESTREL 1-1
Joshua, good morning again. It’s Kestrel 1-1 flight of three. We are complete in 2515 and now standing up for five miles out, straight-in 30 full stop at Mojave.
KESTREL 1-1
Joshua, good morning again. It’s the Kestrel group of three. We’ve finished our work in area 2515 and we’re now lining up five miles out for a straight-in landing on runway three-zero at Mojave.
ATC - JOSHUA APPROACH
Kestrel 1-1, Joshua Approach. Altimeter 30.04. Traffic 10 miles north of Mojave, southwest bound, Brasilia at 12,500. Ident.
ATC - JOSHUA APPROACH
Kestrel 1-1, Joshua Approach. Keep your gauges at 30.04. Watch for another plane ten miles north of Mojave heading southwest, a Brasilia at 12,500 feet. Press your signal button so I can find you on radar.
KESTREL 1-1
Ident, Kestrel. Copy the traffic.
KESTREL 1-1
Signal button pressed, Kestrel. We see that other plane.
ATC - JOSHUA APPROACH
Kestrel 1-1, radar contact 12 miles southeast of Mojave airport.
ATC - JOSHUA APPROACH
Kestrel 1-1, I have you on my radar screen twelve miles southeast of the Mojave airport.
KESTREL 1-1
Kestrel.
KESTREL 1-1
Kestrel copies.
ATC - JOSHUA APPROACH
405 Papa Alpha, traffic two o’clock, 13 miles, westbound, a flight of three inbound to Mojave.
ATC - JOSHUA APPROACH
Plane 405 Papa Alpha, look out to your front-right at the two o’clock position, 13 miles away. There’s a group of three planes heading west toward Mojave.
PILOT - 405PA
Alright, looking for that traffic, 405 Papa Alpha. Did that Boom aircraft take off earlier today or no?
PILOT - 405PA
Alright, we're scanning the sky for those other planes, 405 Papa Alpha. Did that experimental Boom jet take off earlier today or not?
ATC - JOSHUA APPROACH
5 Papa Alpha, that flight of three traffic is the Boom aircraft. It’s heading back to Mojave and it’s at your two o’clock.
ATC - JOSHUA APPROACH
405 Papa Alpha, that group of three planes is the Boom aircraft. They're heading back to Mojave Airport and you'll see them slightly to your right, at the two o'clock position.
PILOT - 405PA
Tell them to slow down so we can get a good look at them.
PILOT - 405PA
Tell those guys to slow down so we can get a better look at them!
KESTREL 1-1
Joshua, Kestrel has the field in sight, ready to switch.
KESTREL 1-1
Joshua radar, the Kestrel flight has the airport in sight; we're ready to switch over to the tower's radio frequency.
ATC - JOSHUA APPROACH
Kestrel 1-1, bridge approach traffic four northwest of Mojave, 12,500. Mojave landing Runway 30, altimeter 30.05. Wind—winds in contact Mojave Tower.
ATC - JOSHUA APPROACH
Kestrel 1-1, there's another plane four miles northwest of Mojave at 12,500 feet. You'll be landing on Runway 30, and the air pressure for your altitude is 30.05. Check with Mojave Tower for the current wind speeds.
KESTREL 1-1
30.05. Thank you for the update. Switching Tower, flight push. Five miles to the south, straight-in for Runway 30.
KESTREL 1-1
30.05 on the pressure setting. Thanks for the update. We're switching to the Tower frequency now, the whole flight is moving over. We're five miles south, coming straight in for Runway 30.
ATC - MOJAVE TOWER
Kestrel 1-1 flight, Mojave Tower. Welcome back. Make that straight-in Runway 30. Are you guys all doing a full stop on this one?
ATC - MOJAVE TOWER
Kestrel flight, this is Mojave Tower. Welcome back. Proceed straight in for Runway 30. Are all three of you planning to land and park on this pass?
KESTREL 1-1
Kestrel 1-1, which is XB-1, will be full stop. 1-2 and 1-3 will do a low approach and then enter right downwind for full stop as well.
KESTREL 1-1
Kestrel 1-1—which is the XB-1 supersonic jet—will be coming in for a full landing. The two chase planes will fly low over the runway first, then circle back around to the right to land behind us.
ATC - MOJAVE TOWER
Roger, Kestrel 1-1. Runway 30, cleared to land. Wind 240 at 3.
ATC - MOJAVE TOWER
Understood, Kestrel 1-1. You are cleared to land on Runway 30. The wind is very light, coming from the southwest at 3 knots.
KESTREL 1-1
Cleared to land 30, Kestrel Flight.
KESTREL 1-1
Cleared to land on Runway 30, Kestrel Flight.
ATC - MOJAVE TOWER
Kestrel 1-2 and 1-3, Runway 30, cleared for the option. On the go, make right closed traffic.
ATC - MOJAVE TOWER
Kestrel 1-2 and 1-3, you're cleared to either land or fly over Runway 30. After that, stay close to the airport and circle back around to the right.
KESTREL 1-1
Cleared for the option, 1-2 and 1-3. One correction, 1-2 and 1-3 will do a right downwind for full stop to follow.
KESTREL 1-1
Cleared for those landing options, 1-2 and 1-3. Just to clarify, the two chase planes will circle around to the right and follow the lead jet in for a full landing.
ATC - MOJAVE TOWER
Kestrel 1-2 and 1-3, Mojave Tower. Roger, approved as requested. Report abeam the numbers, Runway 30.
ATC - MOJAVE TOWER
Kestrel 1-2 and 1-3, Mojave Tower. Copy that, your plan is approved. Let me know when you are flying parallel to the start of Runway 30.
KESTREL 1-1
Will report, Kestrel.
KESTREL 1-1
We'll let you know when we're there, Kestrel.
ATC - MOJAVE TOWER
Kestrel 1-1, welcome back and congratulations. Turn left at the end and taxi to parking via Alpha, cross Runway 22.
ATC - MOJAVE TOWER
Kestrel 1-1, welcome back and congratulations on the flight. Turn left at the end of the runway and drive to parking using taxiway Alpha, and you're clear to cross over Runway 22.
KESTREL 1-1
Kestrel 1-1, thank you.
KESTREL 1-1
Kestrel 1-1, thank you.
KESTREL 1-1
Tower, Kestrel 1-2 and 1-3 are at the numbers, full stop 30.
KESTREL 1-1
Tower, Kestrel 1-2 and 1-3 are at the start of the runway, coming in for a full landing on Runway 30.
ATC - MOJAVE TOWER
Kestrel 1-2 and 1-3, Runway 30, cleared to land. Wind 310 at 4. Company clearing the runway.
ATC - MOJAVE TOWER
Kestrel 1-2 and 1-3, you are cleared to land on Runway 30. The wind is light at 4 knots. Your teammate’s plane is currently clearing the runway.
KESTREL 1-1
Copy, traffic in sight. Cleared to land 30, both aircraft, Kestrel.
KESTREL 1-1
Copy that, we have the other plane in sight. Both Kestrel aircraft are cleared to land on Runway 30.
ATC - MOJAVE GROUND
Kestrel 1-1, Mojave Ground. Congratulations. Taxi to park via Charlie, cross 22. Stay this frequency.
ATC - MOJAVE GROUND
Kestrel 1-1, this is Mojave Ground. Congratulations! Drive to the parking area via taxiway Charlie and cross over Runway 22. Stay on this radio channel.
ATC - MOJAVE TOWER
Kestrel 1-2 and 1-3, you can turn left at your discretion. Taxi to parking via Alpha and hold short of all runways.
ATC - MOJAVE TOWER
[Unclear response]
KESTREL 1-1
Taxi back at our discretion, left on Alpha, hold short. Kestrel.
KESTREL 1-1
Kestrel 1-2 and 1-3, you can turn left whenever you’re ready. Drive to parking via taxiway Alpha and stop before you reach any runways.
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