The backseater later indicated slow speed of 155 knots, pilot saw 152 knots or 175 mph. The SR-71 at that point was gently floating down, control certainly would have been lost completely had not Blackbird pilot Brian Shul firewalled the throttles.
The SR-71, the most advanced member of the Blackbird family that included the A-12 and YF-12, was designed by a team of Lockheed personnel led by Clarence “Kelly” Johnson, then vice president of Lockheed’s Advanced Development Company Projects, commonly known as the “Skunk Works” and now a part of Lockheed Martin.
The Blackbird design originated in secrecy during the late 1950s with the A-12 reconnaissance aircraft that first flew in April 1962 and remained classified until 1976. President Lyndon Johnson publicly announced the existence of the YF-12A interceptor variant on Feb. 29, 1964, more than half a year after its maiden flight. The SR-71 completed its first flight on Dec. 22, 1964.
The Blackbird was designed to cruise at “Mach 3+,” just over three times the speed of sound or more than 2,200 miles per hour and at altitudes up to 85,000 feet.
When talking about the “Blackbird family” probably the most frequently asked Blackbird question is-how high and how fast does it really fly?
As you may remember we already answered this question HERE and HERE.
But what about the slowest speed ever recorded by a Blackbird?
‘I was flying the SR-71 out of RAF Mildenhall, England, with my backseater, Walt Watson. We were returning from a mission over Europe and the Iron Curtain when we received a radio transmission from home base,’ remembers Brian Shul, former SR-71 Blackbird pilot, in his book Sled Driver.

Rex Lowe, former USAF Staff Sergeant, explains what happened later on Quora.
‘The aircrew was asked to make a low level pass of a British airfield where cadets were training. Having difficulty actually sighting the field, though navigation was dead on, the pilot, Brian Shul, realized the aircraft was below advertised flying airspeed, he lit the burners and darted off. The backseater later indicated slow speed of 155 knots, pilot saw 152 knots or 175 mph. The aircraft at that point was gently floating down, control certainly would have been lost completely had not Shul firewalled the throttles.’
This is probably the slowest speed ever flown by a Lockheed Blackbird.
However, after landing Shul and Watson were met by their commander.
Shul remembers;
‘We were both certain he was reaching for our wings. Instead, he heartily shook our hands and said the commander had told him it was the greatest SR-71 fly-past he had ever seen, especially how we had surprised them with such a precise maneuver that could only be described as breathtaking. […]Walt and I both understood the concept of “breathtaking” very well that morning and sheepishly replied that they were just excited to see our low approach.’
Photo credit: courtesy of Robin Harbour

Not to burst anyone’s bubble here but I am fairly certain that this story is fake. This story is an accounting from Major Brian Shul, and taken at face value one would automatically assume such a story from such a person is believable but the fact is this person has a tendency to tell wild stories, more than a regular person would. Take this story for example where are the people who can corroborate this story? I haven’t heard of a single person from this event come forward nor where there any recordings which would not be uncommon for the time.
Also a better example of why this is likely faked comes from one of the best known stories told by this Major Brian Shul, the infamous ATC speed check story, as the story goes a number of pilots piloting a number of different aircraft reply ranging from a small private Cessna and a small passenger prop to a Navy F/A-18 and the SR-71 call out for a speed check from ATC. All of the pilots hear each other’s call outs, and each try to 1up the other. However this is not possible as ATC does not speak to private, commercial and military all on the same frequencies , this was confirmed by a true SR-71 pilot. Additionally ATC at that time were not capable of giving readouts for speed on aircraft going above 990 so the readout for the SR-71 couldn’t have been accurately seen, in fact as an ex ATC said they actually would get a report saying SC (Speed Classified).
AceArchangel – actually, if you have read the book Sled Driver, you’ll know there are witnesses quoted in the book about this incident. If I remember correctly, they encountered a group of officers at Incirlik, and they were talking about the fly-by in the officer’s club. I’ll hunt up my PDF of the book and confirm, but there WERE witnesses.
https://theaviationgeekclub.com/story-behind-famed-sr-71-blackbird-super-low-knife-edge-pass/
As we retired to the equipment room to change from space suits to flight suits, we just sat there-we hadn’t spoken a word since “the pass.” Finally, Walter looked at me and said, “One hundred fifty-six knots. What did you see?” Trying to find my voice, I stammered, “One hundred fifty-two.” We sat in silence for a moment. Then Walt said, “Don’t ever do that to me again!” And I never did.
A year later, Walter and I were having lunch in the Mildenhall Officer’s club, and overheard an officer talking to some cadets about an SR-71 fly-past that he had seen one day. Of course, by now the story included kids falling off the tower and screaming as the heat of the jet singed their eyebrows. Noticing our HABU patches, as we stood there with lunch trays in our hands, he asked us to verify to the cadets that such a thing had occurred. Walt just shook his head and said, “It was probably just a routine low approach; they’re pretty impressive in that plane.”