Drop the Ban on Supersonic Aircraft

by on June 13, 2016 at 7:25 am in Economics, Law, Travel | Permalink

WSJ: In the 1960s the future of aviation seemed bright. In 1958 Boeing had built its first jetliner, the 707, which cruised at speeds of up to 600 mph. The Concorde came along in 1969, flying at Mach 2—more than 1,500 mph. An age of affordable supersonic flight seemed inevitable, promising U.S. coast-to-coast travel in just 90 minutes.

Today, neither the Concorde nor any other supersonic passenger jet operates. And the 707, still in limited use, remains one of the fastest commercial jets operating in the world. What happened?

Regulation happened. In 1973, shortly after Boeing abandoned the 2707, its Mach 3 government-funded competitor to the British- and French-made Concorde, the Federal Aviation Administration issued a rule banning supersonic transport over the U.S.

And why did we ban supersonic transport? It seems almost like a joke–because we were worried about noise. What would Chuck Yeager say? (He’s still alive and re-enacted his 1947 supersonic flight in 2012 at the age of 89).

Moreover, the noise scare was overblown. Incredibly, it was only after the FAA banned supersonic transport over the US that a careful study was done at Heathrow airport and that study found that the Concorde taking off and landing was only modestly louder than a regular jet. Moreover, as the study reported:

Whenever there was a Concorde departure from Heathrow, subsonic jets recorded a higher or equal noise level at the relevant fixed monitoring sites on 2 days out of 3.

The technology to produce quieter supersonic aircraft exists today but we won’t see really big investment in the industry until the outright ban on supersonic aircraft is lifted. As Dourado and Hammond write:

If the original ban was an overreaction, today it’s an outright absurdity—and remains in place due more to regulatory inertia and the FAA’s deeply precautionary culture than a sober accounting of costs and benefits.

I suspect that we will eventually lift the ban and get quieter and faster supersonic aircraft. But when we do so don’t make the mistake of thinking that it was wise to wait. As I pointed out in my earlier piece on Uber of the Sky, technological development is endogenous. If you ban supersonic aircraft, the money, experience and learning by doing needed to develop quieter supersonic aircraft won’t exist. A ban will make technological developments in the industry much slower and dependent upon exogeneous progress in other industries.

When we ban a new technology we have to think not just about the costs and benefits of a ban today but about the costs and benefits on the entire glide path of the technology.

1 John Schilling June 13, 2016 at 7:35 am

The FAA study you cite was done in 1977. And it was done at Heathrow, where the Concorde would have been flying well below the speed of sound.

Airliners of that era, many of which are still in service elsewhere in the world, have been essentially barred from most North American and European airports on noise grounds. If the Concorde was “only modestly louder” than a 1970s airliner even in subsonic flight, then it would be grounded today without any specific ban on supersonic transport, We now insist on airplanes that are 10-20 dB quieter than airliners of the 1970s.

And maybe that’s because we’re a bunch of wimps who can’t handle the Sound of Freedom like Real Manly Men could in ages of yore, but come on: Noise pollution is as pure an externality as you can get, the sort of thing the most hardcore libertarian agrees that there needs to be some sort of rule about, and the democratic process in the US and Europe seems to be indicating that the rule is going to be fairly restrictive.

2 Lord Action June 13, 2016 at 9:53 am


Nice summary.

3 JWatts June 13, 2016 at 11:59 am

” If the Concorde was “only modestly louder” than a 1970s airliner even in subsonic flight, then it would be grounded today without any specific ban on supersonic transport,”

Then logically you should agree with Alex’s point. Why place a general ban against supersonic transit when the issue in contention is the noise? The existing noise regulations provide effective regulation. The rest seems superfluous.

4 cowboydroid June 13, 2016 at 1:35 pm

You’re bringing reason to a gunfight. You’ll probably lose.

5 Jay June 13, 2016 at 1:38 pm

Agreed, my conclusion would be to drop the (somewhat) arbitrary supersonic part which can’t be innovated away and keep the noise restriction which can given the incentive to.

6 mulp June 13, 2016 at 2:13 pm

Oil and coal companies fund environmental opposition to wind farms based on bird kills even though their waste ponds and spills kill more birds than wind farms do. Nuclear plant operators are attacking nat gas power generation based on carbon emissions even though the way they operate the nuke plants (95% rated power 95% of the time) mandates the use of fossil plants to follow the loads which they want to be their decades old coal plants – using subsidies provided by Congress or States.

It’s all competition. The US government cancelled subsidies for a US SST so US Air craft makers and air carriers did not want the competition.

Aircraft noise was already a hot issue, so FUD on noise was a great tactic to block competition.

Aircraft Noise Abatement Act (1968) [Pub.L. 90-411]
Authorized the FAA to prescribe standards for the measurement of aircraft noise and to establish regulations to abate noise. This Act was modified by the Noise Control Act of 1972, in which the Congress required the FAA to consult with the EPA in prescribing standards and regulations.

Noise Control Act (1972) [Pub.L. 92-574, sec. 1]
This act amended the Federal Aviation Act to involve the U.S. Environmental Protection Agency in the regulation of airport noise. “The Congress declares that it is the policy of the United States to promote an environment for all Americans free from noise that jeopardizes their health or welfare.” The Act was passed because Congress was dissatisfied with FAA progress in noise abatement. Under the Act the FAA is required to hold public hearings on aircraft noise regulations proposed by the EPA but is not required to adopt the regulations.

Airport and Airway Development Act Amendments (1976) [Pub.L. 94-353]
Amends Airport and Airway Development Act of 1970 to include authority to grant funds for land acquisition for noise abatement programs. It also increased the federal governmenet’s matching share of airport development projects for large airports from 50% to 75%.

Quiet Communities Act (1978) [Pub.L. 95-609]
This act provides for coordination of federal research and activities in noise control, amending portions of the Noise Control Act of 1972. The Act was intended to speed up FAA response to noise regulations proposed by the EPA and requires the FAA to provide the public with a detailed analysis of EPA proposals. It also authorized FAA funds for development of noise abatement plans around airports. Eligible projects included construction of barriers and acoustical shielding, sound-proofing of buildings, and acquisition of land and air easements to achieve compatibility with noise standards.

Aviation Safety and Noise Abatement Act (1979) [Pub.L. 96-193]
Title I of this Act gives the FAA authority to issue regulations on “air noise compatibility planning” and to make funds available for airport projects contained in an approved noise compatibility program. These regulations have been published by the FAA in 14 Code of Federal Regulations Part 150. The Act also required the Secretary of Transportation to establish federal standards for measuring and assessing noise impacts on residences near airports.

Concorde was not ready for commercial flight operations until 1976, so the airport noise issue far preceeded Concorde becoming a reality.

I’ve been following noise issues at airports at Logan and Manchester airports in New England for four decades because it has been such a persistent legal, property, environmental issues in the news. And I was familiar with the issue in a Chicago for a decade or so where O’Hara was built way way way outside of town to avoid the complaints about such things as noise, only to have everything crowd in around it leading to complaints as it expanded as planned.

But it wasn’t noise that killed Concorde or environmentalists, but conservatives who oppose massive government spending to get things like Concorde built. Conservatives blame environmentalists for their killing of nuclear because conservatives opposed the massive subsidies, or much higher prices, of nuclear power.

Conservatives want very low labor costs and very high profits and low prices, and when that isn’t possible, it’s those wacko environmentalists or civil rights leftists to blame.

7 Bill June 13, 2016 at 7:40 am

Re: “I suspect that we will eventually lift the ban and get quieter and faster supersonic aircraft.”

I suspect that you will not be able to overcome the laws of physics when an aircraft exceeds supersonic speeds.

I’m holding out for the tele transponder that deconstructs your physical body and sends it electronically through the airwaves to another planet without creating a thunderclap.

8 dan1111 June 13, 2016 at 8:03 am

There is actually ongoing research into this area, with some success already:


9 dan1111 June 13, 2016 at 8:04 am

Errrr…quieter sonic booms, I mean–not teleporters.

10 Bill June 13, 2016 at 8:56 am

Same difference.

11 Pshrnk June 13, 2016 at 1:38 pm

I’m waiting for the Houston to Seattle hyperloop.

12 mulp June 13, 2016 at 2:22 pm

“I suspect that you will not be able to overcome the laws of physics when an aircraft exceeds supersonic speeds.”

It is the laws of economic and human rights that make supersonic aircraft impossible.

Until conservatives agree to be slaves and work themselves to death designing and building such aircraft, the Wall Street rent seeking on the huge funding of the labor costs required to build supersonic aircraft to the point of being able to build 200 per year and sell them at a cost per passenger on par with a Dreamliner, the odds are higher for Wall Street funding 20,000 miles of hyperloop across the US.

13 The Engineer June 13, 2016 at 7:42 am

Growing up on the south shore of Long Island, every once in a while when the atmospheric conditions were right, you could hear the Concord taking off from JFK, and it sounded like the end of the world. But it was infrequent.

But that was takeoff with afterburners, not supersonic flight causing that noise. Not the same thing.

I’ve never personally heard a sonic boom.

I would guess that supersonic flight will never be available to the general public because it uses way too much fuel. But I bet there is a market for supersonic private jets for the Trumps of the world.

14 bellisaurius June 13, 2016 at 8:24 am

And, at any rate, the lower lying fruit for time savings is probably on the security gate/entry stuff.

15 Alex from G June 13, 2016 at 9:50 am

Since people are the the risk factor here, anesthetizing passengers for a given timeframe would be of great help. Also, flight experience would dramatically improve for passengers. No more airplane food jokes. And handing the flight attendants tranquilizer guns would also improve their job satisfaction as well. It’d be win-win.

16 bellisaurius June 13, 2016 at 10:43 am

Here at Dada Airlines, we like to let you fly high. Really High…

17 Daniel Weber June 13, 2016 at 8:55 am

But that was takeoff with afterburners, not supersonic flight causing that noise. Not the same thing.

I felt bait-and-switched when the discussion changed from noise concerns when traveling super-sonic to noise concerns at take-off.

18 Mark Thorson June 13, 2016 at 9:45 am

I’ve heard lots of them. They were a regular occurrence here in SIlicon Valley when I was a kid. You actually feel them more than hear them. It’s like a very short, sharp earthquake. The last one I felt was in the early 1970’s, probably around 1972. That was a weird one — my family was sure it was an earthquake, but later the news reported it was a B-1 breaking the sound barrier 70 miles off the coast. I was surprised it could produce such a large boom at that distance.

19 floyd June 13, 2016 at 10:13 am

The B-1 wasn’t flying in 1972.

20 albatross June 13, 2016 at 12:41 pm

So, apparently the boom made when breaking the light barrier is even more impressive than the one made when breaking the sound barrier.

21 Mark Thorson June 13, 2016 at 12:51 pm

“Around 1972” would encompass its first flight (according to Wikipedia) in 1974. Heck, I might have heard it in 1975.

22 Steve Sailer June 13, 2016 at 6:37 pm

In the San Fernando Valley, near Lockheed, sonic booms were a regular occurrence in the 1960s. After awhile they were restricted to up near Edwards AFB and Area 51.

In general, the military isn’t all that excited about supersonic flight anymore. The F-104 (variously known as the Widowmaker and the Coffin Nail) flew twice the speed of sound six decades ago. The Shooting Star’s maximum speed was considerably faster than the maximum speed of the latest F-35.

23 Mondfledermaus June 13, 2016 at 11:17 am

When I lived in Orlando I did get to hear the Space Shuttle on the way back, Kennedy Space Center was about 60 miles away, and it was loud, and the walls shook quite a bit. It was a waking up experience.

24 Five Daarstens June 13, 2016 at 1:46 pm

My family is from South Brooklyn and I would hear them on occasion, IMHO they were twice as loud as a normal jet, and that would be non-supersonic.

25 j r June 14, 2016 at 2:40 am

I grew up right across the bay from JFK and I remember that noise well, much louder than the normal jets.

26 dan1111 June 13, 2016 at 7:55 am

The post’s discussion of the evidence about supersonic aircraft noise is fundamentally flawed.

The implication that the FAA ban was not evidence-based is incorrect. In fact, there was extensive testing to study people’s experience of sonic booms (https://en.wikipedia.org/wiki/Oklahoma_City_sonic_boom_tests), as well as experience from the operation of military aircraft.

And as John Schilling notes, the Heathrow tests were at subsonic speed.

27 Steve Sailer June 13, 2016 at 6:31 pm

Right, take off and landing noise is a completely different problem than sonic booms.

My father worked at Lockheed, which prototyped the L-2000 supersonic airliner in the 1960s, but was rejected by the government in favor of Boeing’s more complicated design, which was canceled in 1971.


Sonic booms were a major problem.

My opinion as a 7 year old was that the people being woken up by sonic booms should just suck it up and gut it out for the glory of technological progress and the future, but more mature people had different ideas, and thus SSTs were only allowed to go supersonic over the ocean.

Perhaps technological advancements can somehow muffle the sonic booms?

The other problem with SSTs was they were envisioned in a pre-1973 environment of super cheap fuel, and thus the Concorde turned out to be a luxury niche product with very expensive tickets.

28 John Schilling June 14, 2016 at 12:14 am

“Right, take off and landing noise is a completely different problem than sonic booms.”

Not completely different, insofar as the type of engine you need to meet modern noise standards is largely unsuitable for supersonic flight, and vice versa. High-bypass turbofans are quiet, efficient, and produce more drag than thrust by the time you get to Mach 2.

29 Michael Savage June 13, 2016 at 7:56 am

I agree with this: “we have to think not just about the costs and benefits of a ban today but about the costs and benefits on the entire glide path of the technology”. But it’s strikes me as the opposite of Alex’s recent argument against historic building preservation laws, where he wanted it all to be about costs and benefits today, and thought we should ignore the ‘glide path’ that would see historic centres demolished in most major cities.

The question of when and how to factor in the ‘glide path’ is a question of taste, and of politics. It’s not just a technical question.

30 Adam June 13, 2016 at 8:00 am

This is fun magical thinking. As if Boeing is just leaving money on the table by acquiescing to regulation, rather than facing real physical and economic constraints.

By all means, lift the ban. We still won’t see supersonic commercial air traffic.

31 dan1111 June 13, 2016 at 8:12 am

It’s pretty clear that Boeing wanted the ban, because they didn’t have a viable competitor to the Concorde.

While that isn’t the situation any more, Boeing still might think that the ban serves their interests: they are a dominant player in the conventional airline market, but it’s an open question who would “win” in a competition to develop new supersonic aircraft. Rapid change threatens to upset the industry. So they could rationally continue to support the ban, even if they think supersonic air travel is viable.

32 Lord Action June 13, 2016 at 9:56 am

Also +1.

It’s not like Boeing is in the business of radically remaking the industry. It is quite happy with industry just how it is now.

33 John June 13, 2016 at 10:15 am

It’s pretty clear that Boeing wanted the ban, because they didn’t have a viable competitor to the Concorde.

Sure they did, the 747. Which, as you may know, is 16x more fuel efficient than Concorde. 16…

34 dan1111 June 13, 2016 at 10:33 am

I don’t think it was obvious at the time that supersonic travel was unviable due to fuel costs. Arguably Boeing feared a future where supersonic aircraft take over the market, and they were left behind.

Also, according to Wikipedia the 747-400 is a bit more than 4x more fuel efficient than the Concorde, not 16X. And this itself was a model with improved fuel efficiency that came out a decade after the Concorde. I don’t know how the earlier 747s compared, as I can’t find a reference. https://en.wikipedia.org/wiki/Fuel_economy_in_aircraft

35 lost_satellite June 13, 2016 at 11:26 am

Maybe on a per-passenger basis? Can’t be bothered to research, but in my head that makes sense.

36 Axa June 13, 2016 at 12:20 pm

The 16 multiple may not be just. I think it’s considering the fuel efficiency of 2nd generation engines and today’s traffic & pricing where occupancy rate for long flights is near 100%. The Concorde was fast, but never full.

37 John June 13, 2016 at 12:23 pm

It looks like you’re right. I’m certain I read 16x somewhere but maybe they were mistaken.

While carrying a full load, Concorde achieved 15.8 passenger miles per gallon of fuel, while the Boeing 707 reached 33.3 pm/g, the Boeing 747 46.4 pm/g, and the McDonnell Douglas DC-10 53.6 pm/g.

By comparison a 787-9 does 99 pm/g.

38 David H. June 13, 2016 at 8:02 am

You can tell yourself this story if you’re really such a “regulation kills all good things” hedgehog, but the real story is that supersonic planes use a whole lot more fuel per passenger, can’t carry many people, are an expensive nightmare to maintain, and weren’t profitable even before the oil shocks. The noise regulation just accelerated the economically inevitable.

39 John June 13, 2016 at 10:20 am

and weren’t profitable even before the oil shocks.

That’s actually not true. Initially the Concorde was hemorrhaging money for BA. As a result, the CEO tasked one of his executives to either find a way to make money or shut Concorde down. Trying to get a handle on ticket prices, he did a survey of passengers asking them how they felt about ticket prices. The responses came back with, “I have no idea how much a ticket costs – my secretary takes care of that.” He then asked how much they thought a ticket costs. They responded with a number that was twice as high as BA was charging. So, they doubled prices and Concorde starting minting money for BA.

40 dan1111 June 13, 2016 at 10:48 am

Higher fuel costs are probably somewhat intractable (though I’m sure there is plenty of potential for improvement).

The other problems you mention could be addressed by further developing the technology.

Maintenance issues/costs and lack of profitability are also symptomatic of a small fleet, which was related to the limited market caused by the ban.

41 albatross June 13, 2016 at 12:43 pm

If they are inherently uneconomical, it’s hard to see why we need a ban on them.

42 JWatts June 13, 2016 at 1:42 pm


43 Brian June 13, 2016 at 8:07 am

I’ve been hiking out in the mountains within 100km of open desert where the Top Gun training program is run. Sometimes the pilots break the rules out there and you get the full sonic boom effect while jets race across the sky at insane pace.

It’s like the end of the world. Loud and shocking the wave of noise from those tiny planes is far more disruptive than anything at a commercial airport. You don’t want that running over populated land.

But there is a lot of demand on Hong Kong-LAX and Tokyo-SFO routes. You could sell hundreds of jets to cross that ocean in five hours if you could make them. And there’s no noise rule. So maybe making them is nowhere near as simple as Alex suggests.

44 Lord Action June 13, 2016 at 9:58 am

In fairness, a lot of people’s experience with booms comes from military overflights at low altitude, which is not what you’d get with civilian airliners at 40k feet. So the comparison may not be enlightening.

45 The Engineer June 13, 2016 at 11:24 am

The Concorde cruised at 60k feet!

46 Lord Action June 13, 2016 at 11:30 am

Exactly. How relevant is fighter jet overflight at 1200 feet?

I don’t know what altitude some future supersonic business jet would fly at over land, but I’m pretty sure it’s not 1200 feet.

47 Jonny5 June 13, 2016 at 11:46 am

The Concorde was loud at sea level.

48 Lord Action June 13, 2016 at 11:53 am

Maybe I’m being unclear. The booming characteristics on low-level military flight is not relevant. Brian was suggesting it was. I just don’t think that’s the case.

Very few people participating in this conversation have ever heard a Concorde overflight. Modern supersonic transport aircraft would likely have different booming characteristics. Whether it’s possible to do a modern supersonic transport aircraft with acceptable noise characteristics, well I don’t really know. I don’t think Alex is right that we can just ignore it. This strikes me as about the perfect case for some sort of regulation.

49 albatross June 13, 2016 at 12:47 pm

Sure, we need regulation of noise, which is a pretty classic externality. But it seems dumb to ban supersonic passenger travel, rather than just regulating the actual noise level measured on the ground. If the physics of the situation forbid supersonic air travel that passes the noise rules, then so be it. And on the other hand, if someone can find a way to do supersonic air travel that doesn’t violate the noise restrictions, then that’s fine, too.

50 prior_test2 June 13, 2016 at 1:59 pm

‘Very few people participating in this conversation have ever heard a Concorde overflight.’

I have, multiple times, living near one of the two American airports where the Concorde flew regular passenger service. And it was, by a large margin, the loudest commercial aircraft I have ever experienced. Nonetheless, a truly impressive aircraft to see fly overhead, particularly as when it missed an approach, there was no question what was causing the house to shake, making it worth looking out to see it at low altitude.

51 Console June 14, 2016 at 12:04 am

The shockwave is worse at altitude because it covers a bigger area. At 40,000 feet, the sonic boom cone is 40 miles in diameter. Same principle behind detonating a nuclear weapon at altitude rather than ground level.

52 rayward June 13, 2016 at 8:09 am

Concorde was withdrawn from service not because it created too much noise but because it created too little profit (as compared to the profits from first class fares on subsonic aircraft). I suspect that Tabarrok has become enamored with the Google business model: if Google can produce driverless cars, why can’t Google (or some other tech company) produce and operate an efficient, safe, profitable supersonic aircraft. What Tabarrok (and many others) forgets is that Google (like many so-called tech companies) isn’t a tech company so much as an advertising platform, generating (very large) profits by selling advertising. The driverless car will allow Google to close the deal by delivering the customer to her destination to buy the product or service advertised on Google. The car itself is just part of the platform. Granted, if Google could figure out how to make a supersonic aircraft part of its advertising platform, they’d do it. Since they haven’t, I suspect they can’t.

53 dan1111 June 13, 2016 at 10:35 am

This is a weird take on driverless cars.

If driverless cars support Google’s core business, it’s more likely by generating free publicity, as well as reinforcing the perception that they are a cutting edge tech company.

54 Lord Action June 13, 2016 at 11:15 am

I’ve heard it argued that they want the location data.

55 Darin June 13, 2016 at 8:35 am

The continued ban might also partially be a result of the influence of aircraft manufacturers, i.e. Boeing. If they felt that they could make a mint with supersonic jets, they would no doubt have pushed for deregulation. If instead however they believe that they and Airbus would have about the same ability to produce the same quality supersonic jets, then the regulation may be a means for them to avoid competition. If the ban was lifted, they might both have to make large investments in technology development without seeing a commensurate increase in profit margins.

56 Sam June 13, 2016 at 8:51 am

This. It’s something of an open secret that the 1973 ban happened because Boeing withdrew their effort and didn’t want domestic competition.

Moreover, the Concorde was designed without a market test, and so always had financial problems. If supersonic were legalized we’d likely see smaller business class jets fill the niche, 40 seaters vs 100 seaters. A smaller regional specialty airline is not what Boeing wants to build for, although they may get drawn into it, as the startups mentioned in the article are making a real push for international SST. Wait to see how elite opinion changes once it’s faster to fly from SFO to Beijing as it is from SFO to JFK.

57 Mike June 13, 2016 at 8:36 am

Growing up in southern New Mexico and west Texas I heard plenty of sonic booms. Even as a military aviation-obsessed kid I only found them cool for about the first week. After that I flinched every time I heard one.

If they can eliminate that, more power to them, otherwise, NFW.

58 anon June 13, 2016 at 8:38 am

With appropriate carbon fuel tax?

59 Lord Action June 13, 2016 at 10:00 am

Fuel is a pretty small fraction of the price of air travel. Supersonic travel is less efficient, but not markedly so. Even if you doubled the fuel costs, it wouldn’t matter much to the business class set.

60 prior_test2 June 13, 2016 at 11:29 am

Strangely, no airline or pasenger airliner manufacturer agrees with you.

61 Lord Action June 13, 2016 at 11:32 am

Do you really think Gulfstream is seriously concerned about their fuel consumption per passenger mile? Care to hazard a guess at how it compares to 747 numbers?

Seriously, where could you have possibly come up with that idea?

62 prior_test2 June 13, 2016 at 1:53 pm

‘Do you really think Gulfstream is seriously concerned about their fuel consumption per passenger mile?’

No. But do you seriously think that Gulfstream is an airline or a passenger airliner manufacturer? (Emphasis on ‘airliner,’ not ‘passenger,’ admittedly.)

That Gulfstream might be interested in selling aircraft capable of supersonic flight is certainly a possibillity – and that such a (likely small) market is not all that price sensitive is likely true.

The Concorde was a prestige object operated by two state owned airlines for much of its operational life – and no one has ever seriously suggested that it made a profit for either airline, much less that its production was profitable.

63 prior_test2 June 13, 2016 at 2:01 pm

About profit – apparently, Wikipedia says the Concorde did operate at a profit near the end of its life. Fair enough – I was under the impression that it never made a profit, but that is apparently incorrect.

64 Richard Gadsden June 14, 2016 at 12:30 pm

Concorde, after BA was privatised, made a profit because it could charge an enormous premium on fares – precisely because it was a prestige project.

People would pay through the nose to say they had flown on Concorde. That only worked because there were very few such flights, and that meant there weren’t enough planes to amortise the design costs.

And then 9/11 happened, followed by the Air France accident, followed by the recognition that these were now going to be really expensive to maintain.

65 TMC June 13, 2016 at 11:43 am


6.1% of the example flight cost.

66 mkt42 June 13, 2016 at 2:13 pm

Their default example is Newark to DC, a very short flight, with an assumed round-trip ticket price of $671, an absurdly high price.

Try entering more realistic numbers, e.g. LAX to DC, with a round-trip airfare of $500 (you’ll have to change the airplane to a 737-800 or the like). Now fuel costs are 41% of the air fare.

67 NPW June 13, 2016 at 2:39 pm

On average, fuel costs are the single highest cost for aviation. Basic research will confirm this.

68 Axa June 13, 2016 at 8:44 am

As mentioned by other people people, airliners make 20 dB less than 40 years before. I remember the noise of a B-727 landing. You could be in the airport restaurant and you knew when it landed. Today, airliners still make noise but if you are in the middle of a conversation you don’t notice aircraft taking-off or landing. So, it’s not good to compare a modern B-737 with the Concorde.

Also, airline investors are more excited for 4% in fuel savings than supersonic travel. http://edition.cnn.com/2016/02/02/aviation/easyjet-hybrid-plane-hydrogen-fuel-cell/

Supersonic travel was just another curious Cold War competition. More than regulation, it’s harder today to convince taxpayers to fund development if they don’t have the incentive of “The Russians are doing it first”.

69 Richard Gadsden June 14, 2016 at 12:37 pm

If supersonic is coming back, it’s coming back as business jets – Gulfstream-sized planes.

No-one is going to do scheduled flights with post-9/11 security levels, as you just don’t gain enough time by flying faster.

NetJets would buy a bunch to break into a higher-level market (people who own their own subsonic will want to time-share a supersonic) and there are quite a few corporations and super-rich individuals – probably a market of a couple of hundred, which would actually cover the development costs, which is why there are a bunch of companies trying to get there.

Oh, and the NFL would buy them for games in England.

70 Benny Lava June 13, 2016 at 8:59 am

Great to see another pile of crap post from Alex. Frame it kids. This is why economics is not a hard science. As others have pointed out the problem with supersonic flight is the sonic boom. And none of the exerpts mention it.

71 anon June 13, 2016 at 9:10 am

Maybe we should say this one explicitly too:

“The high Mach number supersonic bomber and its commercial transport version represent a challenge not only to designers but to fuel suppliers. Opinions differ on the relative importance of speed, structure and power plant but most designers are agreed that, compared to today’s jet aircraft, the supersonic jet is far more fuel dependent in terms of both quality and cost. Fuel represents about 50% of gross take-off weight and accounts for over 50% of direct operating costs in the supersonic transport. The higher fuel consumption of supersonic jet engines means that the SST consumes more fuel to move the same traffic over a given route than the subsonic jet. As a consequence, a significantly greater demand for jet fuel will exist if some portion of world traffic moves supersonically rather than by conventional aircraft. Economic analysis indicates that fuel costs significantly greater than current fuel might wipe out the incentive for airlines to acquire a SST instead of a subsonic jet.”


72 anon June 13, 2016 at 9:28 am

BTW, that was a 1961 paper that worried about “fuel costs significantly greater than current.”

73 Albigensian June 13, 2016 at 10:06 am

Concorde was actually reasonably fuel-efficient when in supersonic cruise, but horribly inefficient when taking off and landing.

That big delta wing worked pretty well at Mach 2.0 but had enormous drag when operating at the high angle of attack necessary to provide enough lift at Mach 0.5 and below.

And those turbojets were also reasonably efficient at Mach 2.0, but both noisy and inefficient for subsonic flight.

Thus Concorde used a huge amount of fuel at the beginning and end of the flight. And poor fuel economy not only has a cost penalty but limits range. Yet surely it is on longer non-stop flights where supersonic travel would have the most value?

The basic engineering challenge is that what works well for supersonic cruise works badly (when it can be made to work at all) in the deep subsonic range, and possible solutions (variable-geometry wings, fanjets used only for subsonic flight) are complex and costly to implement.

Thus development costs (which are already enormous for large subsonic jets, even though this is a mature technology) can be expected to be very large indeed. To cover those costs, either expected unit sales must be very high or the unit price must be very high and, how much of a market is there for premium long-distance air travel and at what price premium?

Finally, given the economic and technical challenges inherent in supersonic transports, perhaps eventually technology will just leapfrog to hypersonic travel (> Mach 5.0) for those really long flights?

74 prior_test2 June 13, 2016 at 10:54 am

‘The basic engineering challenge is that what works well for supersonic cruise works badly (when it can be made to work at all) in the deep subsonic range, and possible solutions (variable-geometry wings, fanjets used only for subsonic flight) are complex and costly to implement.’

Well, the droopy noise worked out OK.

75 prior_test2 June 13, 2016 at 11:17 am

Well, ‘droopy nose.’

Though the droop did involve noise, in a certain abstract sense – the nose needed to be a different position for landing/take off due to the high angle of attack impeding a pilot’s sight, compared to a position of aerodynamic efficiency in actual flight.

76 Lord Action June 13, 2016 at 11:21 am

I was under the impression the droopy nose was one of the worst things about the aircraft, because of weight and complexity. Apparently the engines, and more specifically the engine control systems, were a real bear to maintain as well.

Both of those problems would be substantially lessened today – for example, we’d rely on cameras and other sensors and never build a droopy nose again, even if we still had to land at such an angle. And modern digital controls would not be the major R&D project the Olympus engine’s system was.

Albigensian is certainly right that the compromise between Mach 2.0 and Mach 0.2 is hard to achieve. I doubt, though, that trying to compromise between Mach 5.0 and Mach 0.2 makes things any easier.

77 prior_test2 June 13, 2016 at 1:47 pm

‘I was under the impression the droopy nose was one of the worst things about the aircraft, because of weight and complexity.’

Well, without that compromise, the plane itself would have essentially not been possible for a pilot to land safely. Whether that makes the nose a good or bad compromise depends on one’s perspective of whether the Concorde should have been built and used in passenger service at all.

The Concorde was many things, including being a regularly scheduled supersonic passenger jet. It was never practical, though.

78 Benjamin Cole June 13, 2016 at 9:16 am

Egads. Has anyone noticed fuel costs as a jet approaches Mach 1?
Even private jets are subsonic…

79 Brett June 13, 2016 at 9:46 am

That’s why I think they’ll be pretty niche stuff even if they’re legalized. The fuel costs of flying supersonic aircraft are huge compared to subsonic passenger planes, and we apparently don’t even fly subsonic passenger planes as fast as we used to because of the fuel expenditure.

80 Cliff June 13, 2016 at 9:47 am


81 Albigensian June 13, 2016 at 10:14 am

Well, yes, you surely don’t want to spend much time anywhere near Mach 1.0. If you’re going supersonic you want to transition through the transonic region as quickly as possible. Which takes plenty of power and therefore is usually done with afterburners, despite the fuel penalty of just throwing fuel out there and igniting it.

82 prior_test2 June 13, 2016 at 10:56 am

‘despite the fuel penalty of just throwing fuel out there and igniting it’

Well, that is pretty much the definition of a scramjet, though the process should involve self-ignition. (Yes, I know, first you have to get the scramjet moving fast enough….)

83 Lord Action June 13, 2016 at 11:25 am


A scramjet is a ramjet in which the gas flow internal to the engine never drops below the speed of sound. Ramjets slow the incoming air down (which heats it up and provides the limit on their operating air speed), burns fuel in it to heat it up further, and then expands it out the back through a nozzle. Scramjets aim to do the same kind of thing, but with less slowing of the incoming air, and hence less heating, and hence the ability to operate at higher speeds.

Albigensian is describing an afterburner, which is a completely different thing.

84 prior_test2 June 13, 2016 at 1:43 pm

Consider it stretching a point too far, then. An afterburner, a ramjet, and a scramjet (leaving aside the question of the speed required for operation) all involve nothing more and nothing less than torching off raw fuel to produce thrust.

As noted here – ‘An afterburner (or a reheat) is a component present on some jet engines, mostly military supersonic aircraft. Its purpose is to provide an increase in thrust, usually for supersonic flight, takeoff and for combat situations. Afterburning is achieved by injecting additional fuel into the jet pipe downstream of (i.e. after) the turbine. The advantage of afterburning is significantly increased thrust; the disadvantage is its very high fuel consumption and inefficiency, though this is often regarded as acceptable for the short periods during which it is usually used.’ https://en.wikipedia.org/wiki/Afterburner

Sc/ramjets merely dispense with the turbine while essentially doing the same thing, with much greater efficiency – that is, fuel is (self-)ignited directly to produce thrust.

85 Cambias June 13, 2016 at 9:35 am

Wasn’t there also some ginned-up concern about supersonic planes destroying the ozone layer?

86 Axa June 13, 2016 at 9:55 am


The impact of high altitude aircraft on the ozone layer in the stratosphere http://link.springer.com/article/10.1007%2FBF00696810

Supersonic aircraft exhaust measured in-flight for first time http://www.publicaffairs.noaa.gov/pr95/oct95/noaa95-65.html

But, I’m an optimist. I think Alex uses the blog as a test ground before talking to a wider and less forgiving audience.

87 Mark Thorson June 13, 2016 at 9:59 am

There was that, but the bigger concern was with — get ready for it — global cooling. To fly supersonic, you also have to fly very high. The fear was that ice crystals forming in the contrails of supersonic aircraft at high altitude would increase the Earth’s reflectivity (albedo), which might risk triggering another ice age.

88 dan1111 June 13, 2016 at 10:50 am

Did people really think that? It seems crazy, as jet contrails would surely cover a miniscule portion of the earth’s surface.

89 Careless June 13, 2016 at 8:17 pm

In the aftermath of 9/11 canceling so many flights, researchers found that the contrails of existing air traffic had a small but measurable effect on temperature (maybe .1 degrees. it’s been 15 years, memory is a bit hazy.

90 prior_test2 June 13, 2016 at 10:57 am

In 1975 or so? Nope.

91 prior_test2 June 13, 2016 at 10:01 am

In 1975 or so? Nope.

92 carlolspln June 13, 2016 at 9:53 am

“When we ban a new technology we have to think not just about the costs and benefits of a ban today but about the costs and benefits on the entire glide path of the technology”

Mr. Tabarork, your naivety is touching. Since all transformative technologies have changed society in ways never envisioned/planned by their creators, you have just articulated an empirical impossibility [“..costs & benefits on the entire glide path of technology”]. *

* eg, the telephone, which Alexander Graham Bell envisioned as a one way channel for broadcasting opera performances – but which penetrated explosively because of its two way communication capability

93 Axolotl Jones June 13, 2016 at 10:04 am

Its always dispiriting when economists ignore economics. There is no insolvable engineering problem in building supersonic transports: that was possible 50 years ago. There were three: the stillborn Boeing 2707, the Soviet Tu-144, and the Anglo-French Concorde. the 2707 was cancelled in 1971 when Congress declined to vote further funding (i.e. subsidies). There were 114 orders for the 2707 when it was cancelled, However, at the same time, there were 74 orders for the Concorde, of all of which were cancelled, save the 12 purchased by government-owned British Airways and Air France. The Tu-144 was only in service briefly. Three of the fourteen Tu-144s were lost in accidents, which probably contributed to the Soviet decision to withdraw it from passenger service after only 55 flights. It is likely that if the US Government had stayed the course, that the 2707 program would eventually have bankrupted some combination of Boeing and the airline purchasers.

The fundamental economic problem with supersonic transports:

–Supersonic cruise only generates appreciable time savings over long distances: 3,000 miles is probably the absolute minimum, but transatlantic and especially transpacific routes (8,000 miles+) generate the big passenger value.
–Supersonic cruise drinks fuel. That is not only costly itself, but requires a big aircraft to carry enough fuel carry a payload over a long distance. You end up (always) with a big, fuel gulping airplane and a relatively small payload.
–Friction raises skin temperatures on supersonic aircraft to a degree that aluminum or composites cannot be used for the skin or other exposed elements. So, a big chunk of the weight of a supersonic aircraft is in expensive, hard-to-make titanium or other exotic materials.
–All aircraft are weight critical and sensitive to details of aerodynamics, but supersonic aircraft are particularly weight critical, acutely sensitive to aerodynamics, and at risk from aerodynamic heating. All this implies intensive design and prolonged testing, which equals high development costs .
–Generally, when the airlines or manufacturers estimate the development costs, figure out how to spread those costs across a prospective fleet of aircraft, work out the size of the market and the average revenue per passenger required, they need a really large fleet to amortize the development costs, but that the ticket prices required define a really small market. And there, for 50 years, the matter has rested, waiting for some Government prepared to ante up billions in development costs.
–BA and Air France were able to give reasonable load factors for a few aircraft, and hence were able to eke out an operating profit, but the British and French governments essentially ate the development costs for Concorde. It was not an economic success, and I doubt that either airline ever wished they had more Concordes.
–It is possible that there is a market for a money-is-no-object supersonic business jet for the super-rich, comparable to the super-yacht business. However, development costs vs. market size continue to be a problem. How many billion-dollar supersonic business jets can one reasonably expect to sell?

94 Steve Sailer June 13, 2016 at 6:49 pm

Lockheed had a 3x the speed of sound jet flying way back in 1962, the YF-12 / SR-71. It was incredibly awesome, but also incredibly expensive to fly and maintain.

Interestingly, the SR-71’s lower tech / lower speed predecessor spy plane, the famous U-2, is still flying for the military as the TR-1.

Supersonic speeds turned out to be more or less of a dead end for most practical uses. Subsonic planes and satellites turned out to be economical, supersonic airplanes not so much.

95 Peter B. Giblett June 13, 2016 at 10:16 am

I think you are mis-stating the reason for the ban. I lived in the Heathrow flight path and do agree that Concorde landing and take-off was not particularly loud compared to other aircraft. The issue however relates not to take off/landing but to in-flight noise associated with the sonic boom that was known to shatter windows on the ground more than 30,000 ft below.

96 ad June 13, 2016 at 1:37 pm

How close did you live to the flight path? I lived in Colnbrook, and the difference between Concorde and anything else was the difference between “loud background noise” and “cannot hear the TV”.

97 prior_test2 June 13, 2016 at 2:10 pm

In the lowest Concorde experiences I’ve had, the difference between a normal mid-70s airliner at 1000 feet and the Concorde was the complete conviction that the Concorde must have caused damage that needed to be checked – cracked house windows, ruined glassware, things falling off shelves, etc.

(Yes, a couple of those missed approaches included the Concorde flying over with its landing gear still down – these occasions were definitely not typical, of course,)

98 Unanimous June 13, 2016 at 8:53 pm

And I lived in Teddington for 3 years as a child. When Concord flew over school everyone had to sit there waiting for 30 seconds while it went over. Out of class you could not continue a conversation with someone next to you. Nor was it practical to turn up the telly. You could still continue all these things when a 727 flew over, even though they would be considered unacceptably loud by modern standards. This wasn’t sonic booms, it was just a stupidly loud plane.

99 Jon June 13, 2016 at 10:50 am

When I lived near Orlando one morning I was awaken by a large boom that rattled everything. It sounded like an explosion. I later learned that was my first experience with the space shuttle’s sonic boom.

Perhaps Alex does not no about this problem, otherwise he would not have raised the level of takeoff and landing noise.

Interestingly no other countries have been interested in allowing sonic booms from routine flights over their territory.

100 Jon June 13, 2016 at 10:51 am

When I lived near Orlando one morning I was awaken by a large boom that rattled everything. It sounded like an explosion. I later learned that was my first experience with the space shuttle’s sonic boom.

Perhaps Alex does not know about this problem, otherwise he would not have raised the level of takeoff and landing noise.

Interestingly no other countries have been interested in allowing sonic booms from routine flights over their territory.

101 Turkey Vulture June 13, 2016 at 10:54 am

Here again, I suspect Alex is thinking he would avoid the negative externalities of supersonic flight (described by many commenters above), while potentially enjoying the benefits of faster air travel (or getting to fly really fast in a cool jet).

102 Urso June 13, 2016 at 12:35 pm

Look, there’s nothing stopping you from negotiating with United Air to change their flight path farther away from your house. Coase and all that.

103 prior_test2 June 13, 2016 at 11:11 am

To add to the personal recollections – I was actually at one of the Fairfax County Board of Supervisor meetings concerning the Concorde in the mid-70s (I’m an actual Eagle Scout – getting some merit badge concerninc civicy required attendance at a local political hearing, and easily 5 uniformed members of Troop 15444 were at that meeting). The Concorde reps (mainly from both airlines) had a lot of cool material to pass out, but the county supervisors seemed a lot more interested in the actual noise levels of the Concorde landing/taking off at Dulles.

Yes, I have experienced the Concorde as a regularly scheduled airliner – watching it come in and turn to land at Dulles was regular event for years, after all, easily seen from near Fairfax City. The DC area (Dulles in particularl) has always had its share of interesting aircraft to see, but the Concorde was distinctly elegant compared to most aircraft, both civil and military, in a 2001 A Space Odyssey fashion.

And yes, I have also experienced the Concorde at low attitude, both at home and school, after missing a landing at Dulles. It is apparent that Prof. Tabarrok did not grow up in Northern Virginia, and clearly has no actual personal experience of what it is like to experience the Concorde at something like a 1000 feet altitude. Maybe he should have, before writing such mockery worthy text.

104 prior_test2 June 13, 2016 at 11:18 am

Man, the day of typos – ‘civics,’ a term likely not used that often anymore.

105 Brian Slesinsky June 13, 2016 at 11:25 am
106 ibaien June 13, 2016 at 11:39 am

all commenters here seem to be missing a key point. a libertarian like our august co-host would simply suggest that if you don’t like living under a supersonic flight path, you could just move to North Dakota. eventually the market will shake itself out and the urban poor can suffer the constant din, which they probably deserve for not having the wherewithal to also move somewhere nicer.

107 albatross June 13, 2016 at 12:54 pm

You know, Alex is quite capable of being wrong all on his own, without strawmanning him.

108 prior_test2 June 13, 2016 at 1:35 pm

Hilariously wrong, in this case.

109 mulp June 13, 2016 at 3:53 pm

Alex is just attacking a strawman.

I’m not sure there was ever a “ban” on supersonic commercial flights. There was never approval for supersonic commercial flight, which would require unique flight corridors for supersonic flight. Concorde flew above commercial flight corridors which are limited to under 40,000 to handle cabin pressure loss.

While the FAA does not have regulatory authority over military aircraft, they do not fly supersonic over land below 30,000 feet outside training areas, and even then, they do not fly at true supersonic speeds, only at ~700 mph, cruise speed, which due to temperature boundary never reaches the ground.

But in any case, the FAA in 2008 issued a press release stating the following:

“Policy Statement:
“The Federal Aviation Administration (FAA) is committed to aviation’s long-
standing efforts to achieve increasingly effective noise abatement at its source. We
anticipate that any future Notice of Proposed Rulemaking issued by the FAA affecting
the noise operating rules would propose that any future supersonic airplane produce no
greater noise impact on a community than a subsonic airplane. Subsonic noise limits
are prescribed in 14 CFR Part 36. The latest noise limit in Part 36 is Stage 4, which
applies to the development of future supersonic airplanes operating at subsonic speeds. ”
Noise standards for supersonic operation will be developed as the unique operational
flight characteristics of supersonic designs become known and the noise impacts of
supersonic flight are shown to be acceptable.”

The Federal government, by law passed by Congress, can not measure noise, or anything else, without a formal determination and rule making on the method of measuring noise, which requires public input, public comment on draft rules, and response to all public comments, before the rule is published yet again in the Federal register as tentatively final, as many such rules are challenged in court and often prohibited from taking effect by injunction.

And if the FAA were proposing supersonic flights over Trump or Koch or Romney properties, they would certainly be behind lawsuits blocking the FAA allowing such flights over their property. Starting with objections to the method of measuring noise of supersonic flight.

110 Tylerh June 13, 2016 at 4:49 pm

We don’t have supersonic transports because the laws of physics disfavor them.

The Air Force can have any bomber or transport it wants — and all the ones it wants (C- 135, C-17 Globemaster, B-2, Long Range Strike Bomber) are sub-sonic.

The key formula is 1/2 mv^2 (” one-half em vee squared.” ) I can explain if anyone cares.

The consequence is any super-sonic bomber or transport will have less range and be more expensive to operate than the equivalent sub-sonic airplane.

Physics, not politics, are the reason we don’t have supersonic transport

111 Joël June 13, 2016 at 5:45 pm

Is this that simple? I mean, does the kinetic energy of the plane
at cruise speed really represents a large part of the total energy used in the flight?
After the plane has achieved its normal speed, it is also important to maintain that speed against air friction during the total duration of the flight. You seem to suggest that this part is negligible. I am not sure that’s correct.

112 tylerh June 14, 2016 at 2:53 pm

Yes, it is this simple. Von Karman worked this out in 30’s ( or may be earlier).

Here’s the physcis problem: you have to push the air molecules out of the way fast enough to let your plane through. The faster you go, the faster you have to move those molecules out of the way.

To move that mass of air out of the way of the airplane, you must impart kinetic energy KE to that mass n:

KE = (1/2) * m * v^2

where v is the velocity of your plane. Where does that kinetic energy come come? ultimately, your fuel tanks.

So if you want to move the same plane the same distance at twice the speed you will need to carry four times as much fuel.

A 747 is happy at 500 mph. If you want your 747 to travel at Mach 2 — roughly 1500 mp – you’ll need 8 times as much fuel.

And here’s the key problem: an airplane must get aloft with all the fuel is will need for the entire flight

The desire to go Mach 2 instead of Mach 0.7 increases the take-off weight of the fuel by a factor of 8.

This is no small matter. A fully loaded 747 takes off with over 300,000 pounds of fuel. To cruise at Mach 2 will require another _two_million_pounds_ of fuel. However, the maximum cargo capacity of a 747 maxes out at less than 400,000 pounds. Tripling the speed simply isn’t possible. If you do want to fly that fast, you have to accept that you vastly less range.

The physics is that simple.

p.s. Notice that I assumed a frictionless airplane. The speed/ range trade off is actually worse than this. potentially much worse, depending on design choices.

How fast? the speed of your plane.

So, to go distance D, you must ove

113 Steve Sailer June 13, 2016 at 7:03 pm

My dad spent much of the 1960s trying to get the supersonic F-104 fighter to not kill so many West German pilots.

The original idea behind supersonic flight was to have an incredibly high performance interceptor to get up and shoot down high altitude Soviet bombers before they nuked Seattle. In the Fifties, the F-104 could get from sea level to 39,000 feet in 99.9 seconds.

But it was originally intended as what my father called a “kamikaze interceptor” — absolute maximum performance getting up to bomber altitude; and then if the pilot managed to turn it around and if the landing strip hadn’t been nuked so he could land it, well that was a plus. But if he ran out of fuel after knocking down a Soviet nuclear bomber, well, that was still Mission Accomplished and his widow would get a decent pension.

Not surprisingly, Air Force pilots didn’t much want to fly this World War III warplane on a routine basis, so they handed it to the Air National Guard, who didn’t much like it either. Then the Lockheed executives came up with idea of selling it to NATO allies as an all purpose low level fighter-bomber. So my dad, a low level engineer, spent many depressing years trying to retrofit fixes onto this bat out of hell to keep less-skilled European pilots from killing themselves so much in it.

In general, militaries around the world have had experience with supersonic planes and aren’t all that eager for more.

114 Justin June 16, 2016 at 6:09 am

“In general, militaries around the world have had experience with supersonic planes and aren’t all that eager for more.”

I’m not smart on the F104, but every fighter in the US inventory is supersonic capable and routinely flies supersonic. There is nothing inherently more dangerous, anymore, about supersonic flight. The F-104’s problems were probably more a function of generally poor design and not it’s supersonic capability per se. Fighter jets of all stripes killed bunches of pilots in the 50s or 60s.

115 Shane M June 13, 2016 at 8:09 pm

More bang for the buck in optimizing going through security, and boarding/deplaning/baggage claim.

116 Ricardo June 14, 2016 at 2:09 am

There seem to be four issues with supersonic aircraft: they can be very loud during takeoff and landing, the sonic boom as they fly overhead can be disturbing, their fuel costs are extremely high and none have the safety record of modern Boeing or Airbus passenger jets. Other than that, they are great.

117 Will June 14, 2016 at 7:49 pm

This post needs some more research. There absolutely was evidence that sonic booms were going to a major issue- the Oklahoma City sonic boom tests are relatively famous and probably would have turned up with a bit of googling. Anyway, the major issues for supersonic flight (besides sonic booms) are fuel cost and lack of passengers. The business model was basically dead before the ban, lifting it isn’t going to change that. Do you think the large aerospace companies don’t have lobbyists? If they thought there was money to made, they’d be making it.

118 Justin June 16, 2016 at 6:06 am

“Whenever there was a Concorde departure from Heathrow, subsonic jets recorded a higher or equal noise level at the relevant fixed monitoring sites on 2 days out of 3.”

But what does this have to do with the price of butter? The increased noise doesn’t come from normal sub-sonic flight, it comes once you are above the sound barrier (the “sonic boom”). This almost will never occur until you are at a high altitude (think which won’t typically occur to at a high altitude). When fighter pilots, including me, accidently go over Mach 1 over land there are noise complaints from a very wide area. There are consistently reports of windows rattling and occasionally broken windows. I personally have never witnessed that, but that is what people report.

Not an argument for or against supersonic flight, just pointing out that measuring noise level at takeoff or landing is pointless.

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