In this video on Wikipedia of Chuck Yeager breaking the sound barrier in the Bell X-1 in level flight, at 2:44 the narrator says "For the first time, except in dive, a man has flown an airplane faster than the speed of sound."

Was the sound barrier recorded being broken previously to the X-1 by someone else in a dive? I can't find any information online about this.

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    $\begingroup$ Check the section "Early Claims" on page: en.wikipedia.org/wiki/Sound_barrier There are multiple claims of people breaking the barrier in a dive. But many are disputed. $\endgroup$
    – abelenky
    Nov 18, 2021 at 17:29
  • $\begingroup$ For instance, there was a claim that an Me-163 Komet became (at least) transonic after being towed to altitude with full tanks and air started (hence not spending most of its fuel climbing) -- but post-War testing suggested the airframe would become uncontrollable above about Mach 0.9, IIRC. $\endgroup$
    – Zeiss Ikon
    Nov 18, 2021 at 17:38
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    $\begingroup$ @Zeiss Ikon: Is there any requirement that the person/aircraft breaking the sound barrier actually has to survive the experience? $\endgroup$
    – jamesqf
    Nov 18, 2021 at 17:42
  • $\begingroup$ Ask the questioner -- but if not, there were surely some folks back in Ottoman days who did it after being shot from a cannon... $\endgroup$
    – Zeiss Ikon
    Nov 18, 2021 at 17:51
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    $\begingroup$ Many an aviator prior to that broke the sound barrier… for a few, terrifying moments. $\endgroup$ Dec 6, 2023 at 21:34

3 Answers 3


It is unlikely WWII era aircraft had instruments that measured mach. So any claims to having gone supersonic could not be proven. If you knew how it felt to pass through the mach, you might claim it, but again no way to prove it. My fastest: mach 1.82.

  • $\begingroup$ Many issues here. Whether WWII era aircraft likely or unlikely to have had instruments that measured Mach doesn't substantiate anything. The answer to the question of the OP does not hinge on availability of instruments in aircraft. So your claim that any claims to having gone supersonic could not be proven is also wrong, because having gone supersonic would not necessarily depend on instruments that were built in the aircraft. In addition, "could not be proven" goes to far, because even if claims were not proven does not mean they could not be proven. Many things in life could be proven $\endgroup$ Dec 2, 2023 at 1:24
  • $\begingroup$ I don't think early mechanical machmeters were really any better than a standard airspeed indicator and altimeter, they just did the math for you. As long as a pilot noted their airspeed and altitude they (or someone else) could later calculate their Mach number. Lacking temperature info it wouldn't have been totally accurate, but neither were the original machmeters which didn't have temperature input. What would matter though is whether the airspeed indicator went high enough. $\endgroup$ Dec 5, 2023 at 4:32

Many WWII fighter could approach Mach 1 in a dive. I believe after the war a P51 reached 0.85 Mach in a steep dive.

There were several undocumented claims that based on indicated airspeed a few planes had managed to reach Mach 1 in a dive.

It is well known that many planes broke up as they approached the transonic region starting around 0.8 Mach.

Most Engineers doubt that any WWII aircraft could have survived breaking the sound barrier.

  • $\begingroup$ The problem was less breaking up but becoming uncontrollable from Mach tuck. There were dozens of cases of dives of fighters during WW II that went straight into the ground. $\endgroup$ Feb 4 at 23:39

There is a possibility that German pilot, Hans Guido Mutke, had broken the sound barrier in a Messerschmitt Me 262 on April 9th, 1945 after diving approximately 3 miles.

As others have mentioned, there is no documentation or way to record this as accurate with instrumentation since the airplane's airspeed indicator was maxed out at 1100kph/683mph/594kts, it was not calibrated with the intention of setting any records, and there were no other witnesses than the pilot.

I suppose someone could possibly test this out "Mythbuster's style" in the future once we get the automated airplane tech figured out or maybe use simulation technology to see if it would have been possible in this type of aircraft without it experiencing a catastrophic failure.


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