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At air shows with fighter jets I would expect there would be a demonstration of supersonic flight. But in this flight of a Eurofighter Typhoon, no sonic boom was heard.

What is the reason?

Is it that there is no supersonic flight involved due to loudness or needing a bigger distance to accelerate?

Or is the sonic boom inaudible for a reason related to the short time delay of the sound between the noise source and the microphone, or some other physical reason?

Volker Siegel
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    Sonic booms over populated areas were essentially forbidden in the US sometime around 1960. Prior to that I heard several. Have not heard one since. – Hot Licks Nov 22 '19 at 20:17
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    I think it was the late 60s because I remember hearing some as a kid. I thought it was cool... – Michael Hall Nov 23 '19 at 00:05
  • I heard sonic bombs as a kid, in the San Fernando Valley part of Los Angeles. Wonder where they were flying out of? We also frequently heard rocket engine testing from the Rocketdyne and Rockwell facilities in the Chatsworth hills. – davidbak Nov 23 '19 at 00:10
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    "I would expect there would be a demonstration of supersonic flight". Why? (I, on the other hand, would hope that there would be a demonstration of supersonic flight.) – RonJohn Nov 24 '19 at 00:14
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    I heard sonic booms on a regular basis in middle Tennessee from '05-'08. They had to flight test the F-22 Raptors over Arnold AFB and there would be 2 sonic booms. One was the F-22, the second was the chase plane. – Ryan Mortensen Nov 24 '19 at 12:45
  • OP, no supersonic flight is allowed at an airshow - it's that simple. – Fattie Nov 24 '19 at 19:05
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    This question is being "over-answered" in very confusing ways. The only thing OP wants to be told is "There is never any supersonic flight at airshows." – Fattie Nov 24 '19 at 19:07
  • In a large part of the video linked in the question, you can see that the fighter has it's flaps deployed (on the leading edge of its wings). That suggests to me (though I'm not a very sophisticated observer of aviation stuff, I could be wrong) that it's at the slower-edge of its performance envelope, and at more risk of stalling than going supersonic. – Blckknght Nov 24 '19 at 19:27
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    @RyanMortensen I worked at Arnold one summer during that period. I hadn't previously heard a sonic boom. When I was meeting with the team I would be working with during my first week there, I remember hearing the building shake as if from a significant explosion and everyone just ignored it and kept talking. Apparently they saw the odd look on my face and said, "Oh, sonic boom," then continued talking about the project. – reirab Jul 08 '20 at 14:23
  • I'm not sure why some people are claiming supersonic flight is not allowed at an airshow, and implying this is true on our entire planet. I've been to multiple airshows that featured supersonic flight. They usually warn you first so you can cover your ears. After the sonic boom, you get to listen to the alarms of most nearby vehicles being triggered. And children crying. – End Anti-Semitic Hate Mar 12 '21 at 20:50
  • @RyanMortensen That is quite interesting, as it shows a direct argument why it is avoided even from a moderate hight that would be "very loud", but acceptable for adults. It is still to loud for children, even with full to protect the child. – Volker Siegel Mar 16 '21 at 09:33
  • The only airshows I have went to are the Blue Angels, and they don't do supersonic. – DaCuteRaccoon Sep 29 '23 at 02:56

4 Answers4

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Just for a bit of flavour, I recall an article from Air Progress from the late 70s about Darryl Greenamyer setting the low altitude absolute speed record, in his "homebuilt" F-104, of Mach 1.3 (mentioned in this article) in 1977.

For the run he had to cross very low over timing trigger devices at the start and end of the speed course at the dry lake bed at Edwards, which were set up with cars parked beside them.

I remember the description of the event by the writer who witnessed it from somewhere along the middle of the course, a safe distance away with other observers. The F-104 passed over the car at the 1st speed trap at 60 ft AGL and passed the writer in absolute silence, and it wasn't until a second or so had passed that a sound like a dynamite explosion a couple hundred feet away went off. All the glass of the cars at the speed traps blew out and their trunks popped open. The writer was warned in no uncertain terms that if he didn't protect his ears he'd get hearing damage, and not to be fooled by the initially silent passage of the jet itself into taking his fingers out of his ears.

Imagine that happening at an airshow.

John K
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    Sound travels at ~1100ft/s. If it was 60ft away, it wouldn't take a couple of seconds. It should basically be instant. – vidarlo Nov 24 '19 at 10:40
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    The boom occurs at the point at which the plane goes supersonic tho, so unless the plane went supersonic as it passed the reporter, they would see a delay. I think they're saying the plane was 60ft away, not that it went supersonic 60ft away. As long as the plane is accelerating, the distance between the plane passing, and the boom passing would be increasing. – djsmiley2kStaysInside Nov 24 '19 at 17:03
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    The aircraft was supersonic before it entered the speed traps and was at 60 ft agl over the speed traps where a car was parked at each end. The reporter wasn't right under the flight path but somewhere around the mid point of the run, perhaps 1-2000 feet from the flight path where various people had assembled to watch. So the shock wave was already trailing the aircraft going into the speed run. If they were 1500 ft away, it would take over a second to reach that far at 1122 fps with a bit extra because the wave is trailing somewhat. I've added some clarification to my post. – John K Nov 24 '19 at 17:31
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    @djsmiley2k-CoW “the boom occurs at the point at which the plane goes supersonic”. This is not correct at all. The “boom” is the wave front of the sound generated by the jet. It is actually a constant roar. The only difference is that the wave front is compressed so that by the time it passes over you that roar happens at a single instance. It travels behind the jet and dissipates outwards at the speed of sound. It is not a single event. It is a continuous sound that you only get to hear a short snippet of. – Fogmeister Nov 24 '19 at 17:51
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    This answer is just an anecdote. It's completely confusing. The OP is asking a very basic question "Is There Supersonic Flight At Airshows?" The four paras here completely fail to simply answer the question! JK, perhaps add one introductory sentence stating the answer, then your anecdote. There's a common problem on these sites where leading experts in a field simply fail to answer very very simple questions, because to the experts it's totally obvious. – Fattie Nov 24 '19 at 19:09
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    I agree that while it is a nice anecdote, it doesn't answer the question. Regarding simple answers to simple questions, I have tried that and been chastised with a canned "we expect long answers" comment. – Michael Hall Nov 24 '19 at 19:55
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    @Fattie That is true, but the anecdote is so interesting that it's worth an answer anyway. I was aware that if it's loud, it is really loud. But that's more than just loud by an order of magnitude or two. I did not expect that, I did not do the math, and if I had, it would not give me an intuition. The answer is implicit, but the implication gives information that other answers can not convey. – Volker Siegel Nov 24 '19 at 20:49
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    As I said folks, "just for a bit of flavour"...Ron already provided the answer. I read that article 40 years ago and it's always stuck with me. – John K Nov 24 '19 at 21:26
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    The "loud" from a sonic boom is not something that is generated from an audio device, but it is pure mechanical pressure released in a very short time frame. You're basically doing something equivalent of dropping rocks on your eardrums directly. Most people don't understand the kind of damage this can cause because they simply have no concept of it. – Nelson Nov 25 '19 at 02:51
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    It's impressive to experience it up close. The US Navy regularly performs airpower demonstrations at sea and I have been on the flight deck for several low altitude supersonic flybys. It is a substantial thump you feel in your whole body when it hits. – Michael Hall Nov 25 '19 at 06:02
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In a lot of areas, sonic booms are illegal over land or near residential areas. Yes it's loud, yes it's potentially damaging, especially at low altitudes. I've been to a lot of airshows, I've never seen a supersonic demo.

Ron Beyer
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  • this is true. In Europe, where the eurofighter is used the most super sonic flight is prohibited by the noise level limits a plane may produce. It is only alowed in acute alarm situations. I whitnessed this once in Nürnberg during an incident. You Really don´t need speakers to hear the boom. It shakes your bones from 15km away. – Nefrin Nov 22 '19 at 11:51
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    @Nefrin Not all European countries have the luxury of the sea to train supersonic flight. In Czechia planned training supersonic flights are performed above 10 km. – Vladimir F Героям слава Nov 22 '19 at 20:28
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    While it's true that some countries (such as the U.S.) make it illegal for civilians to fly supersonic over land, this restriction is rarely, if ever, legally applicable to the military. Of course, they'll still not do this at low altitude under normal circumstances for obvious reasons. Even in the U.S. where supersonic flight over land is notoriously banned for civilians, the military does it pretty regularly, just at high altitudes. We used to hear sonic booms pretty frequently near the USAF base I used to work at. It was far enough away not to do damage, but it did shake the building. – reirab Nov 22 '19 at 22:10
  • @reirab, I’m not saying it doesn’t occasionally happen, but military pilots are not allowed to fly supersonic in CONUS. – Michael Hall Nov 23 '19 at 19:08
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    @MichaelHall I mean, I know they're not allowed to just whenever they want, but there are plenty of (relatively frequent in my experience) missions where they can and do fly supersonic over the CONUS. Of course, it's not like they're doing it at 1,000 ft AGL over populated areas. – reirab Nov 23 '19 at 21:03
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    Please help us understand when and where you have seen this occur then because in all the exercises I have been involved in if there was an accidental boom the perpetrator would be shamed in the debrief. – Michael Hall Nov 23 '19 at 21:14
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    @Michael: see https://en.wikipedia.org/wiki/MythBusters_(2009_season)#Sonic_Boom_Sound-off. Not only did Hyneman and Savage prove that sonic booms aren't likely to damage windows on the ground, they performed their experiment in the US (Yuma, AZ to be exact). Yes, there are restrictions about where aircraft can fly supersonic over the US. But a complete blanket prohibition? Nope. – Peter Duniho Nov 25 '19 at 01:38
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    I live near the US Naval Academy, they do sonic boom shows both the day of and the day before graduation. – AAM111 Nov 25 '19 at 04:22
  • Ok, i admit it can be waivered under special circumstances, just like other regulations. I'm just trying to dispel the notion that military pilots are routinely exempt. – Michael Hall Nov 25 '19 at 05:39
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Sonic booms have a lot of, lot of, lot of throw. There would be no way to confine a sonic boom to just the airfield. People two towns over would have have car alarms set off and houses shaken. It would upset animals, it would upset people! It would trigger PTSD for some and panics for others. It would generate hundreds of phone calls to 911.

Keep in mind the airplane has to accelerate to and through supersonic well before the airfield, and then has to slow down again. It's covering a mile every 5 seconds, so this, combined with the throw, sweeps a whole lot of area.

Harper - Reinstate Monica
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  • Does that mean that it's illegal to have an aircraft with a higher landing speed than 250KIAS? I know some extreme aircraft (e.g. the Shuttle) land at very high speeds. – Skyler Nov 22 '19 at 18:42
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    @Skyler Military does not need to foloow civilian rules. One is GAT, one is OAT. – Vladimir F Героям слава Nov 22 '19 at 20:20
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    @Skyler Even civilians can get the 250 below 10,000 speed restriction waived by ATC. It's mostly just there to make traffic deconfliction easier. If ATC has other ways to guarantee no traffic conflicts (and, for the Space Shuttle, they definitely did,) then there's no problem with waiving the speed restriction. – reirab Nov 22 '19 at 22:29
  • @Vladimir, The military definitely does need to follow civilian FAA rules. Some aircraft have waivers for speed, and of course 250 can be exceeded in special use airspace, but otherwise most of the same rules apply. – Michael Hall Nov 23 '19 at 00:04
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    They don't need to follow civilian system, they just do as a matter of policy, because of Hughes 706. – Harper - Reinstate Monica Nov 23 '19 at 00:30
  • @Harper, please declare your credentials for making such a claim. I flew in the military for 20 years and I don’t think you know what you are talking about. – Michael Hall Nov 23 '19 at 19:06
  • @Michael I would imagine this question https://aviation.stackexchange.com/questions/12401/how-much-jurisdiction-does-the-faa-have-over-military-aircraft – Notts90 Nov 24 '19 at 16:14
  • It is a big leap from a detailed explanation of waivers, special use airspace, etc. to an unqualified statement that military pilots don't have to comply with FAA regulations. Roughly 75% of our flying was IFR in the national airspace system. You'd better believe we were required to follow the rules, flight violations are a career killer! Speak with authority on computer programming if that is your specialty, but don't condense someone else's answer into an authoritative sounding summary unless you are able to provide some context for clarity. – Michael Hall Nov 24 '19 at 20:03
  • @MichaelHall It sounds like I've pushed a hot button for you. You seem to be swerving out of your way to misinterpret what I said. I am claiming you, as a line pilot, must - must - follow ATC, because of orders to that effect. I'm saying those orders flow from high up on your chain of command, i.e. Pentagon. Any problem with that so far? – Harper - Reinstate Monica Nov 24 '19 at 22:06
  • You said "they don't need to follow civilian system, they just do as a matter of policy". While the Pentagon is certainly not within the jurisdiction of the FAA, the fact that the military requires their pilots to follow all applicable FAA regulations renders your point completely moot. You and others make it sound like we have a choice in the matter, and could fly supersonic without consequences if we wanted. So yes, I have a problem with that so far. – Michael Hall Nov 24 '19 at 23:46
  • @MichaelHall I never said it's at the discretion of individual pilots. If others did, take it up with them. I am not them. My "they" pronoun referred to your statement "the military", and in my thinking, military is plural because you have to enumerate "Army Navy Air Force Marines" otherwise you're including Coast Guard. – Harper - Reinstate Monica Nov 25 '19 at 00:01
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    When I say "policy" I mean the policies set as a result of the agreement between the armed serviceS and FAA that they would follow ATC (mostly). https://news.google.com/newspapers?id=y3YlAAAAIBAJ&sjid=1fIFAAAAIBAJ&pg=1008,835673&hl=en As a result of the agreement, Congress did not mandate it with legislation. in actual implementation, it is at the services' discretion, but they have to make a good showing of it if they don't want Congress to intervene. – Harper - Reinstate Monica Nov 25 '19 at 00:18
  • Please describe what you mean by "mostly", specifically in the context of an individual military pilot's understanding of a requirement to follow FAA regulations regarding a prohibition against supersonic flight, and any consequences, (or lack thereof) for failing to comply. – Michael Hall Nov 25 '19 at 00:27
  • "mostly" means you follow orders, or stand at account for not doing so. The benefit of an agreement instead of legislation is that this gives top Pentagon brass a range of discretion to a) initially implement the agreement in a sensible manner that allows planning, and b) deviate from the agreement where exigencies require. This is why it's good that it's an agreement and not legislation. All of this is "above the pay grade" of a line pilot. – Harper - Reinstate Monica Nov 25 '19 at 00:32
  • Fair enough, I respect your apparent knowledge on the subject. I have heard that the brass generally won't defend a pilot against an FAA flight deviation though, so you are correct in that the net effect is transparent to a line pilot. – Michael Hall Nov 25 '19 at 05:46
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John K has already provided an example of what a sonic boom feels like from very close, and Harper - Reinstate Monica describes it in general terms. Let me give you a practical example of what a sonic boom did in a radius of 100 km.

On 22 March 2018, Air France flight AF671A from Réunion to Paris Orly was flying over northern Italy when it lost radio contact with Air Traffic Control. Two Eurofighter Typhoons were sent to investigate, and as they rushed there they broke the sound barrier.

The sonic booms were heard from Aosta to Bergamo, which are 180 km apart. And at first they were mistaken for bombs. The result? Among other things, there were hundreds of calls to the police, people ran out of buildings in panic, some schools and offices were evacuated, and some windows got broken.

And at an airshow they'd fly much lower, so it would be louder!

To be fair, it was explained that the wind and weather conditions were unfortunate, as they favoured the propagation of sound, but in any case a sonic boom is way too loud to be done for fun: it's only allowed in case of emergencies.

By the way, in the end it turned out it was a false alarm, so at least there was a happy ending.

[Sources: in English, in Italian]

Fabio says Reinstate Monica
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