SR-71 RSO tells the story behind this video of a Blackbird creating ’13 Fireballs’ during Air Fete Air Show 1986 at RAF Mildenhall

SR-71 RSO tells the story of when two Blackbird spy planes Generated Tri-Sonic Booms over Hanoi to signal a POW escape

By Linda Sheffield Miller
May 1 2022
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‘The mission was a complete success. No one could believe that we came within two seconds of the mark,’ Colonel Richard “Butch” Sheffield, SR-71 Blackbird RSO.

The Sound of Freedom. 50 years ago, on May 2, 1972.

During the Vietnam War, the word was out that the prisoners that the Vietnamese had captured were being tortured. They were struggling to find a plan to rescue the POWs. Attempts to escape had been met with beatings for the entire camp of prisoners of war if one person attempted to escape. In May 1972 a new plan was installed telling the POWs that if they hear the sound of thunder that they were to escape and run down to the river where there would be Navy SEALs waiting to rescue them. There was disagreement among the inmates about whether to risk another escape. A senior POW convinced them that it wasn’t right to make everyone in the camp suffer if they were captured during the escape. Without knowing that the POWs were not going to escape the plan went forth.

The plan was for two SR-71 Blackbird spy planes to fly over the Hanoi Hilton.

The flight plan was to fly the SR‘s so close that their sonic booms would be only 30 seconds apart.

On May 2 and May 4 this happened.

The rest of the story is from my father Colonel Richard “Butch” Sheffield unpublished book.

POW signal, May 2, 1972, SR-71 number, 979, first of three aircraft. The first indication I had that we might fly a mission like this, (where two SR-71 would crisscross over North Vietnam thirty seconds apart), was when one of the planners asked me at the OL “how close, in time, can you come over a point on the ground?” I told him, “as close as you want.” I don’t think he believed me because he said, “can you come to the point within thirty seconds to two minutes?” I said, “of course, we can control airspeed and reach the point at the time you want us to be at the point in space.”

Here’s how two little Dents placed on the Nose of the SR-71 prevented Surface-to-air Missiles from Scoring any Hit on the Blackbird
Richard Butch Sheffield and Bob Spencer

We had this capability because we had insisted at Edwards’, in 1965, that we know the time to the next point, (time to go) something the computer experts and engineers at Edwards’ never thought about and never understood why we needed this information.

I found out later that our Vice Wing Commander, Denny Sullivan [former A-11 pilot (as many of the original SR-71 crewmembers called the A-12) and CIA operative] had been called to Washington and was tasked to fly a mission that would place two SR-71’s over Hanoi, coming from different directions, thirty seconds apart. The mission was to be so secret that Denny came straight to Kadena and tasked us to fly it without stopping at SAC, March Field or Beale Headquarters. In other words, this mission did not go through the normal planning by JCS and SAC. I believe they did not know.


Flying the mission was easy. All we asked for was a destination point be placed in the computer where they wanted us to be and the time to be there.

The mission planners told us to make it as close to thirty seconds as we could and they realized that would be very hard to do because we would be closing on each other at a combined speed of Mach six.

Hanoi Hilton

Bob Spencer and I, Richard “Butch” Sheffield we were the senior crew in the wing at the time, and Chief of the Standardization Division; were selected to lead both the missions and take off first. Darrel Cobb and Reg Blackwell was the spare crew and took off later to position themselves to replace either aircraft. Tom Pugh and Ron Rice took off about an hour later and met us over Hanoi.

After refueling over Thailand, we climbed to altitude and heading north along the China boarder. Once we reach the speed were our inlets and spikes programmed properly, we clicked our mike to single Cobb and Blackwell that we were OK and going on to the target. They flew a random course back to Kadena. About three days after we landed back at Kadena, the staff decided to look at Cobb and Blackwell’s film collected on the random course back to Kadena. A POW camp was found.

On May 4, 1972 we did it all over again the same exact mission (SR-71 number 980, first of three).

Same results, but we shaved one half second off the separation time to thirty-one and one half second.

We came across Hanoi on a southerly heading at seventy-six-thousand feet at Mach 3.17; Pugh and Rice came across the same point, thirty-two seconds after us, at seventy eight-thousand feet on a westerly heading.

The mission was a complete success. No one could believe that we came within two seconds of the mark.

SR-71 print
This print is available in multiple sizes from – CLICK HERE TO GET YOURS. SR-71A Blackbird 61-7972 “Skunkworks”

Colonel Dennis Sullivan our vice Commander said in a letter of Outstanding Crew Performance dated 8 May, 1972 that “The verified time interval on these missions never exceeded one second of the target time interval”.

Several months later, we all received a letter from Colonel Sullivan for our file thanking us for the mission success. At that time, we were told that we were singling the POW’s. After the war, I talked to several POW’s who were in Hanoi when we came over and asked them if they heard us that day. They said, “Yes,” but they didn’t know why.

I understand that some SR pilots who came along years later have been saying the booms were simultaneous. That is not so, they were thirty-one seconds apart. I served on two promotion boards with former POW’s, they said they heard the two distinct booms, but did not know why we did it.

I now know that it was to signal the POW’s, the book, “Operation Thunderhead”, written by Navy SEAL Kevin Dockery that confirms it.

I am proud of my father that he participated in and helped in the planning of the mission of the sound of freedom.

Be sure to check out Linda Sheffield Miller (Col Richard (Butch) Sheffield’s daughter, Col. Sheffield was an SR-71 Reconnaissance Systems Officer) Facebook Page Habubrats for awesome Blackbird’s photos and stories.

Photo credit: U.S. Air Force, Stuart Freer and Linda Sheffield Miller

Lockheed SR-71 Blackbird model
This model is available from AirModels – CLICK HERE TO GET YOURS.

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Linda Sheffield Miller

Linda Sheffield Miller

Grew up at Beale Air Force Base, California. I am a Habubrat. Graduated from North Dakota State University. Former Public School Substitute Teacher, (all subjects all grades). Member of the DAR (Daughters of the Revolutionary War). I am interested in History, especially the history of SR-71. Married, Mother of three wonderful daughters and four extremely handsome grandsons. I live near Washington, DC.

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