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Tail wind

I once faced off against Paul Williams of Reading University in a radio debate. He came across as a pretty rational kind of guy and we had a nice exchange of emails afterwards. But I have to say that his most recent paper is one of those ones that make you despair with their sheer futility. Here's the BBC take on it.

Flights from the UK to the US could take longer due to the changes in the climate, according to a new study.

Global warming is likely to speed up the jet stream, say researchers, and slow down aeroplanes heading for the US.

While eastbound flights from the US will be quicker, roundtrip journeys will "significantly lengthen".

It's published in Environmental Research Letters, which is usually not a good sign. The authors apparently fed "synthetic atmospheric wind fields generated from climate model simulations into a routing algorithm of the type used operationally by flight planners" and deduced that westbound transatlantic flights were going to take longer while eastbound flights will be faster. But, almost inevitably, the losses are expected to outweight the gains.

I wonder what evidence there is that GCMs can predict, or even hindcast, changes in wind speeds in a warming world? 

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Reader Comments (109)

@Mike Post Feb 10, 2016 at 11:33 AM |

Was on one of those flying Dino's from JFK to LHR and the BA Captain confirmed about half hour knocked off due to JS...circa 1982.

Less booze as a result?

Feb 10, 2016 at 2:15 PM | Unregistered CommenterEx-expat Colin

With a difference in +/- 30 minutes on a transatlantic flight, will there be any improvement in the quality of airline food? Or the time taken to dump luggage on the carousel?

These are the real issues that make a difference. Who gives a flying fig for phantasy physics?

Feb 10, 2016 at 2:44 PM | Unregistered Commentergolf charlie

If this happened, the losses would outweigh(t?) the gains. Say jetstream produces 350 knot tailwind east bound. 350 knot airliner would then have groundspeed of 700 knots and make trip in say 4 1/2 hours. Conversely the return would take a very long time indeed, very long.

Feb 10, 2016 at 2:49 PM | Registered Commenterjferguson

AFAIK jet streams are fairly shallow - they do not have much vertical extent. Therefore in a headwind altitude can be changed to avoid the flow, and likewise to take advantage of a tailwind.

Feb 10, 2016 at 2:50 PM | Unregistered CommenterJohn Constable


No wonder the al beeboids went mental - "globull warbling will affect your hols!"

A anyone can see, in recent days the Jet stream has swung south and there is building a continental blocking anticyclone across the Russo-Europe, this means cold what it means for pilots and air-miles is charting slightly different flight paths et bloody cetera and doyaknowwhat - dem been doin' dat for since dey started flying cross da pond.

Pressure shift situations, Jet Stream, Coriolis force-axial spin, temp gradients - it's all in the mix and not a lot to do with mankind CO₂............ to make claims "we are effecting the Jet stream" is fundamentally flawed as it is specious nonsense - actually.

Williams - execrable expostulation - sit in the corner you dunce.

Feb 10, 2016 at 2:56 PM | Unregistered CommenterAthelstan.

TerryS quoted and where's physics: "> Probably that they're based on some pretty fundamental laws of physics.

It's also a pretty fundamental law of physics that when the surface heats up from an ice-age to an interglacial, that the ground will heat up. It's also a pretty fundamental law that the earth will then expand. And it's thus pretty fundamental that we will see a modulation of plate tectonics as a result of the repeated cycle into and out of the ice-ages.

Now show me a single academic who has ever referred to what I call that "Caterpillar effect"
For diagram see: I see no Caterpillar by Josh

There's even recently been concrete evidence this is happening from repeated variations in rock types at the mid oceanic ridges.

What this tells us is that academia is highly selective about what "fundamental physics" it decides to promote.

Feb 10, 2016 at 3:09 PM | Unregistered Commentermike Haseler

Ex Pat Colin

Indeed. My son and wife arrived back from JFK on Monday something like 50 minutes early thanks to the Jetstream.

Of course, a little O/T, a third runway at LHR would cut holding delays and could have a significant impact on flight times and fuel used.

Feb 10, 2016 at 3:12 PM | Unregistered CommenterMike Post

As usual, you have to look into history to see real records...

5 hr 1 min JFK-PWK

And one that got away 5 hr 4 min JFK-PWK might have been under 5 hr if ATC had let them make a direct approach.

Feb 10, 2016 at 3:13 PM | Unregistered CommenterIt doesn't add up...

This was on the news at one on the beeb today, as the newscaster finished the item, someone in the background burst out laughing.
It was probably unrelated, but it made me smile. Maybe their are some people with common sense at the beeb

Feb 10, 2016 at 3:28 PM | Unregistered CommenterEternalOptimist

1. AFAIK, East-West and West-East routings have always been deliberately different so as to minimise headwind flying west and to maximise tailwind flying east. So what is to stop the same policy being applied in future? Eg flying to Japan , Jetstream is flown East-bound and a Great Circle route is flown West-bound. I will check with my Bass player, who is a 747 Captain, although other pilots here can comment I am sure.

2. AFAIK the effect of AGW is expected to differentially warm the poles more than the equator. This will reduce temperature gradient between the two areas and the obvious conclusion is therefore that actual wind energy will go down, not up (same for extreme weather). Lindzen is on record at the HoC hearings pointing out this simple and obvious fact from fundamental physics.

Wiki sums this up quite succinctly:

Jet streams are caused by a combination of a planet's rotation on its axis and atmospheric heating (by solar radiation and, on some planets other than Earth, internal heat). Jet streams form near boundaries of adjacent air masses with significant differences in temperature, such as the polar region and the warmer air towards the equator.

Note the importance of the rotation of the planet.

3.AFAIK there is no tropospheric "hotspot" detected which would actually be the fingerprint of AGW.

4. AFAIK no amount of "Fundamental Physics" will help you model a dual coupled chaotic climate system on a rotating sphere using the Navier-Stokes equations. Anyone who wants to argue the "Fundamental Physics" of that, I suggest they take it up with Rob Brown at Duke...

Feb 10, 2016 at 3:32 PM | Registered Commenterthinkingscientist

Addendum to my post above, in the same Jetstream article on Wiki:

Climate scientists have hypothesized that the jet stream will gradually weaken as a result of global warming. Trends such as Arctic sea ice decline, reduced snow cover, evapotranspiration patterns, and other weather anomalies are expected to make the Arctic heat up faster than other parts of the globe. This in turn reduces the temperature gradient that drives jet stream winds, causing the jet stream to become weaker and more variable in its course.

Presumably if Connoll(e)y didn't approve of this explanation, as representative of the High Priests of CAGW, his edit pawmarks would be all over the page. They are not. But maybe the page is about to be changed by a High Priest of CAGW, to bring it in line with the BBC news story?

Or maybe "climate scientists" have no predictive skills whatsoever and one lot think the Jetstream will weaken and the next minute another lot claim it will get stronger. And either scenario always makes things worse. At least the current Jetstream/climate change statement at Wiki is consistent with fundamental physics.

Feb 10, 2016 at 3:43 PM | Registered Commenterthinkingscientist

Mike Post (11:33 am) -
6:35 flying westbound? Is that a typo, or were the winds reversed that day?

Feb 10, 2016 at 3:43 PM | Registered CommenterHaroldW


Re your point 1, you are quite correct but thanks to the need to keep the huge amount of traffic safely separated, the track system makes sure that nobody gets the ideal route on any particular day. The imagined global warming effect on flight times will be just that, imaginary.

Feb 10, 2016 at 3:46 PM | Unregistered CommenterMike Post

I file this under: possible, but who cares, is it worth spending valuable research money on?

Feb 10, 2016 at 12:01 PM | Unregistered CommenterTheBigYinJames

Call me cynical, but I think it's probably just that air traffic-control is one of the few occupations left where 'climate scientists' haven't made some claim to expertise, and where they also see a potential source of untapped funding. They are drilling hard.

Feb 10, 2016 at 3:53 PM | Unregistered Commentermichael hart

Harold W

Well spotted! I was on the wrong line in my logbook. The outbound on the BA117 on 22 June was 7.23. The inbound on the BA 112 was 6.35. My apologies. My records are all archived!

Feb 10, 2016 at 3:57 PM | Unregistered CommenterMike Post

This sounded familiar to me. Karnauskas et al. discussed this effect in a Nature Climate Change paper ("Coupling between air travel and climate") 6 months ago, for Pacific routes (Hawaii-LA/San Francisco/Seattle). [Non-paywalled version here.] They noted a seasonal variation of about 10 minutes in observed round-trip time due to winds, strongly correlated to ENSO and Arctic Oscillation (AO).

Take-away line: "On average, round-trip flights along these paths will get about 1 minute longer by 2090." Forgive me if I don't get worked up about this, even assuming that the GCM predictions have skill in this area.

Feb 10, 2016 at 4:09 PM | Registered CommenterHaroldW

A paper was published last year which looked at thousands of actual air flight times over the Pacific over 20 years.

"Their analysis also determined that the difference in flight times between eastbound and westbound flights on any given route didn’t cancel each other out; rather there was a residual. In other words, when an eastbound flight became 10 minutes shorter, the corresponding westbound flight became 11 minutes longer.

According to Karnauskas, it took some “obsessive drilling into the data to find that residual, and at face value it seems very minor.” The net additional flying time for a pair of eastbound and westbound flights between, for example, Honolulu and LA is only a couple minutes for every 10 mph speedup of the prevailing wind.But, he says, “the wind really fluctuates by about 40 mph, so multiply those couple of minutes by each flight per day, by each carrier, by each route, and that residual adds up quickly. We're talking millions of dollars in changes in fuel costs.”

The graphs shown in the link don't suggest any trend over the 20 years, but do show a distinct correlation with El Nino events. (I've not located the original paper, just this article about it).

Oops - crossposted about the same paper as HaroldW!

Feb 10, 2016 at 4:10 PM | Registered CommenterRuth Dixon

"Their analysis also determined that the difference in flight times between eastbound and westbound flights on any given route didn’t cancel each other out; rather there was a residual. In other words, when an eastbound flight became 10 minutes shorter, the corresponding westbound flight became 11 minutes longer."

Can they really be so stupid?

If the headwind in one direction is equal to the tailwind in the other direction, while the airspeed remains constant, then the arithmetic mean travel time (A + B) / 2 will of course not be constant.

What, however, WILL be constant is the harmonic mean 2 / (1/A + 1/B).

This was known by Pythagoras.

Feb 10, 2016 at 4:29 PM | Unregistered CommenterBruce Hoult

Climatology is the only science I know where cause and effect are routinely transposed.

Feb 10, 2016 at 4:43 PM | Unregistered CommenterAlan Poirier

The subsonic transatlantic flight record to the UK appears to be 5 hr 1 min JFK-PWK

Feb 10, 2016 at 4:45 PM | Unregistered CommenterIt doesn't add up...

So global warming will speed up the jet stream?
That must be why the jet stream in summer is so much faster... right? Of course it isn't:

Feb 10, 2016 at 4:54 PM | Unregistered CommenterTomRude

Posts about fastest commercial subsonic transatlantic flight times seem to be disappearing. Five hours one minute to beat in a VC10 JFK to Prestwick in 1979.

Feb 10, 2016 at 4:55 PM | Unregistered CommenterIt doesn't add up...

Bruce Hoult - good spot! Of course, its the slowness that averages arithmetically, not the velocity (or speed). As any good geophysicist knows!

Feb 10, 2016 at 4:58 PM | Registered Commenterthinkingscientist

Here is the University of Reading Press release.

Notice that there is no mention of the fact that the predicted lengthening of the round trip is 1 minute. But there is the completely false claim that
"The net result is that roundtrip journeys will significantly lengthen."

Not for the first time, we see that the responsibility for the misleading media story lies with the climate scientist and his university media team, not the media. this is both gobsmacking and worrying.

Of course, if we had any half-decent investigative journalists, they could have dug a bit deeper and asked some awkward questions.

Feb 10, 2016 at 5:12 PM | Registered CommenterPaul Matthews

If it is published in Environmental Research Letters, it is an indication of irrelevance, inaccuracy and inability to do anything useful.

How is ERL actually funded?

Feb 10, 2016 at 5:19 PM | Unregistered Commentergolf charlie

After all these comments I just have to relate a bad joke that my friend, a 747 pilot notorious for bad jokes, told me about 30 years ago...

Two widows, who'd never flown before, decided to visit Hawaii. Over the Pacific in a 747, the pilot announced that he had to shut down one engine, that there was no danger, but they'd be 30 minutes late.
A little later, he shut down another engine, and said they'd be an hour late.
Then he shut down a third engine and said they'd be 2 hours late.
One lady finally said to the other, "Heavens, if we lose the last engine we'll be up here forever!"

Feb 10, 2016 at 5:31 PM | Unregistered CommenterDave Bob

"The wrong kind of jet stream." --michael hart

But it's a robust wrong kind of jet stream.

"Do they not think there is any chance that airlines might alter the flightpaths in response to the strength, direction etc of the jetstream?" --agn

If you intend to fly from, say, London to New York, the shortest flightpath is primarily East to West. To pirouette around the jetstream, means making the flightpath longer. The only alteration in flightpath that will reduce #/hr fuel consumption is to turn around and fly West to East, by way of, say, China. They will then proceed to shoot you down, making the entire exercise even sillier than it already is.

I do not think "significantly lengthen" means what they think it means. They are, after all, talking about a 78 second increase on a 12+hour round trip (less than 0.2%) by means of a doubling of CO2 (which will occur more than 50 years hence).

It also appears to me that their models only accounted for wind speed, not any AGW-driven change in temperature or air density at the assumed flight level. Those two factors are probably quite small, but then, so is the author's reported total effect.

Not that it matters, though, when placed against improvements in aircraft routing, aircraft fuel efficiency and passenger load factor. These directly affect fuel per passenger-mile, and have both shown steady improvement over time.

PLF alone has improved from ~55% to ~80% in the last 50 years. Even small incremental improvements going forward would clearly outstrip the effect of their result. I see no reason to think routing and fuel efficiency won't also increase.

Feb 10, 2016 at 5:41 PM | Unregistered Commenterkch

78 seconds on a return flight across the Atlantic? Too stupid for words. I'd like to throw these people out of said aircraft at 38,000 feet over said Atlantic. Lighter aircraft would travel faster and hence re-gain the lost time. Double bonus.

Feb 10, 2016 at 6:09 PM | Unregistered CommenterCheshireRed

As we have probably had this effect very strongly from about 1950-2016 what does the data from all these flights say has happened already. We have to remember that due to the logarithmic nature of AGW we have probably seen the major effects already.

Feb 10, 2016 at 6:13 PM | Unregistered CommenterRob Burton

@ Rob Burton, capital thinking! What does the data say? I'm sure there's a detectable signal due to increased jet stream winds. The only problem is how to remove the effects of those parameters described by kch a few posts above. Surely we can filter out those effects by applying a weighted regression for route travel time against global temperature. Because this is clearly a well established relationship, fundamental physics really, we will screen out routes that don't have a positive correlation of increasing travel time with temperature. Let's face it though, sometimes the world works in ways that we simply don't understand, so we should allow for negative correlations as well as positive ones. We shouldn't confuse academia though, so we needn't mention that in our high impact publication.

Gin up a graph with a lot of curves, highlight modern temperature in red (using momentum filters of course) and Bob's yer uncle!

Feb 10, 2016 at 6:40 PM | Unregistered CommenterEarle

To confabulate laws of physics with the modeling program results is to demonstrate an amazing degree of ignorance, especially from someone who claims to be a teacher.
And since the models have been proven to be useless for regional or long range forecasts, the amount of ignorance ATTP seems to rely on is awe inspiring.

Feb 10, 2016 at 7:23 PM | Unregistered Commenterhunter

Mike Post (3:57 PM) -
Thanks for the clarification. That makes more sense!

Ruth Dixon -
Funny we should end up posting within a minute of each other!

Earle, Rob Burton -
The Karnauskas et al. paper mentioned earlier in comments did not identify a significant trend, per Ruth Dixon's comment. I suspect that a trend, if present, would only be detectable over a relatively long period of time. Even the predictions for c.2100 are for a mere 1 minute change in average round-trip time, for a round trip of ~10 hours, with a seasonal variation of ~10 minutes plus random variation (whose size I can't recall, or wasn't stated). The problem with detection of a trend over a long period is that the mix of aircraft models change (among other things), and I suspect that these other effects are as large as (or larger than) any climate change effect.

Feb 10, 2016 at 7:37 PM | Registered CommenterHaroldW

"And since the models have been proven to be useless for regional or long range forecasts, the amount of ignorance ATTP seems to rely on is awe inspiring."


When naif's play at politics and in an attempt to justify and legitimize all their half baked climate prognostications. Predictions of future climate, based on nothing but a totally false premise, invoking work done by scientivist bodgers whose use of and through poorly understood science. Next, with their unsound, computer models GCMs which are not fit for purpose, and preposterously backing it all up via appallingly amateurish statistical method .

It's not so much "awe inspiring" more, it evokes a mocking scorn.

For Godssakes, some of them (Ms. Bryony Worthington, Chris Huhne, Miliband, Benn, Ed Potato brain) have held the levers of power, small wonder is it not that - thanks to the insanity of that unilateral industrial suicide pact - the Climate Change Act 2008...... Here in the UK, what remains of our industrial and manufacturing base is being blasted to kingdom come, the economy is going down the tubes at a rate of knots not even the Chinese can match. Plus, don't be fooled by another funny money housing bubble and equity boom Osbornionomics, the economy is in Zombie land and has been since Bliar came to power back in 1997 and prudence MacMental "end to boom and bust" yep - he put an end to boom alright.

Mind you, another recession and this time it will be bad, it has to happen, the western world needs to wean itself of welfarism, green boondoggles, fiat money and yet unregulated reserve banking and corporate greed ref Goldman Sachs, hedge fund feeding frenzies.

It will be: Back to basics.

Feb 10, 2016 at 8:10 PM | Unregistered CommenterAthelstan.

Mike Haseler: "You have got to be kidding! Is that what counts as news in the BBC?"

Answer - yes. Meanwhile, things like the IME report about impending blackouts thanks to replacing reliable and efficient generating technology with unreliable and inefficient "renewables" didn't get a mention. I stand to be corrected, but I couldn't find it on the BBC website, nor did I see it on any news programme.

I used to be a big fan of the BBC. Now it's so chock full of propaganda and censorship it makes me despair.

Feb 10, 2016 at 8:29 PM | Unregistered CommenterMark Hodgson

Eternal Optimist: "Maybe there are some people with common sense at the beeb".

I can see why you're called Eternal Optimist ;-)

Feb 10, 2016 at 8:36 PM | Unregistered CommenterMark Hodgson

Athelstan at 8.10pm - well said. And thanks for making me smile ."Prudence McMental" - inspired!

Feb 10, 2016 at 8:46 PM | Unregistered CommenterMark Hodgson

Consequently, the mean round-trip journey time lengthens by 1 min 18 s

This is just so many angels dancing on the head of a pin. I heard a guy check in with London on his approach from the west the other day. He was told to 'slow down to minimum safe speed and expect a 10 minute delay'. He was lucky, it could have been a much bigger delay.

Why are we paying people to study nonsense like this? Who are the idiots that are totally unaware that runway capacity is the major problem in the UK?

Feb 10, 2016 at 9:40 PM | Unregistered CommenterBilly Liar

Mark Hodgson

The IME report was widely broadcast - see
But does not appear to have been reported on the BBC News website so far as I can see.

Feb 10, 2016 at 9:42 PM | Unregistered CommenterMike Post

Why is everything I read about anthropogenic CO2 bad. When CO2 brought us out of Snowball Earth and the earth warmed it was all good. At some point it all started to be bad. When was that tipping point and why?

So as warm air rises in equatorial regions and cooler air moves in at a lower level from the temperate areas, the risen warm air moves north and as it cools it also moves closer to the earth's axis of rotation. Good old conservation of angular momentum means that as its distance from earth's axis decreases then like a ballerina pulling in her arms this air speeds up to conserve angular momentum. Now if CO2 causes this air to move further north so it will undoubtedly get closer to the earth's axis of rotation and so rotate even faster. But CO2 is meant to warm the poles more quickly than the Tropics and it's also supposed to create a tropospheric hotspot (which nobody has detected yet).

So with the jetstream moving further north its overall path around the earth will tend to shorten ie there won't be so much airspace containing the jetstream. That must mean that more flights can avoid the jetstream if they wish.

Cold air will be kept further north and there should be fewer cold winters in temperate latitudes.

I seem to be generating good news, this can't be right, overload, overload. Aaagh!!

Feb 10, 2016 at 10:26 PM | Unregistered Commenterson of mulder

I thought that the polar regions were supposed to be warming faster than the rest of the world (Cowtan & Way). This reduces the net temperature gradient between polar air and tropical air which slows the Jet Stream ! Groan.

Feb 10, 2016 at 10:30 PM | Unregistered CommenterClive Best

Of course, the really important factors on journey length have much more to do with aircraft design in response to economic factors and technology. The VC10 (and even the Boeing 707) had a rather faster cruising speed than most of today's aircraft because fuel was cheap when it was designed and built. Modern airframes have mainly been designed for derated cruise speeds at greatly enhanced fuel efficiency. Important for longer haul journeys is the longer range of modern aircraft - eliminating refuelling stops, a by-product of higher fuel efficiency, which continues to improve as engine design, aerodynamic design, use of weight saving components (which in turn reduce the weight of fuel required), and improved load factors all make progress.

Aircraft routing to avoid war zones has increased journey times, as has ATC restriction and congestion on busy routes. Some of these factors are addressed by improving navigation technology.

One factor that has greatly lengthened journeys is increased check-in times associated with extra security theatre.

Perhaps the authors should have considered what really matters to journey lengths.

Feb 11, 2016 at 12:06 AM | Unregistered CommenterIt doesn't add up...

I see that no-one in the good old incompetent Beeb bothered to ask anyone who knows about aviation for an opinion. That is less than surprising.

Of course credentials and expertise are not everything, but my job is to teach pilots a broad range of subjects for the hardest flight-crew ground exams around, for the EASA (European Aviation Safety Agency) Airline Transport Pilot's Licence. I have several years of commercial flight experience, and friends in many airlines around the world. So I know aviation.

This just does not pass the smell test.

"...aircraft will collectively be airborne for an extra 2000 h each year..."

This is insane, even ignoring the contradiction of the words "collectively" and "each", which suggests that the writer of the article and the reviewers have not the slightest idea what they are even trying to say. Are they saying collectively they will be airborne 2000 hours more, or that each aircraft will? The first is unbelievably trivial, the second unbelievably large.

World average is about 6 or 7 crews per aircraft, suggesting about an extra 300 hours for each crew per year. Even being really conservative and assuming half that (if transatlantic aircraft happen to be busier and have more crews) that is ... bizarre. To put it in perspective the legal maximum flight time for any crew member in most countries is 900 hours per year, and most medium and long-haul crews will fly 6 or 700, although some will fly 900. Are they really suggesting an increase of 1/6 to 1/3 in flight times? 2 to 4 hours on a New York - London flight, 3-6 on a Florida to London?

Another way of looking at it is that 2000 hours is nearly 40 hours a week - more than a working year for a 9 to 5 job taking holiday into account - or almost 5.5 hours a day. This is where even knowlessmen should have started to baulk at the figures.

That is nuts even for current aircraft, but the new generation (such as the 787) are more efficient at higher speeds, so the effect will be smaller (both beneficial tailwinds and the penalties for headwinds).

Actually, having just slotted in the last paragraph but one I am giving up. This is just too obviously flawed to be taken seriously.

Feb 11, 2016 at 12:34 AM | Unregistered CommenterDoubting Rich

When pondering the implications of this study, it is useful to reflect that one the signs of bad science is when large claims are made about extremely marginal results.

Feb 11, 2016 at 12:43 AM | Unregistered Commenterhunter

Eternal Optimist: "Maybe there are some people with common sense at the beeb".

If so, porcine aerobatics are on the horizon.

It's worse than I expected. I have now read further. I see "...a predicted round-trip journey-time increase of 1 min 35 s...". For 2000 hours a year. Implying around 75000 round trips per annum, or 200 per day.

Even if they meant 2000 minutes a day that is insane, as it would mean more than 3 round trips per aircraft per day. They do one. The North-Atlantic Track Structure only allows for trips Europe to N America in the day, N America to Europe overnight for most aircraft.

At 1 min 35 s that is 577 minutes a year if there is no maintenance (which there must be; it is legally required). That is less than 10 hours per annum. Taking a 767 burning about 5000 kg per hour in a high-speed cruise (less at low speed) that is under 50,000 kg a year. At a specific gravity of 0.79, typical for Jet A1 it's 16,700 US gallons (author did not specify US or Imperial, it's about 14,000 Imp gal). So his 7.2 million gallons implies about 5000 aircraft crossing the pond each way every day, which is too high but not by a factor of 200 as the erroneous figure from which he appears to derive the 7.2 million gallons figure is. A lot of aircraft do cross.

"7.2 million gallons of jet fuel at a cost of US$ 22 million"

This suggests that Jet A1 is about $1.25 a litre. It is hard to find specific prices for Jet A1 but currently club members at Fenland pay about $1.09 at the bowser (or rather £0.75) for Jet A1 (as of Dec 2015).

I suspect British Airways pays somewhat less. I cannot imagine they have paid $1.25 for some time.

So his errors are not consistent. From reading this, using only figures that could be obtained from a brief internet search I can show that it is impossible to trace the figures this fool has come up with in his abstract and relate them to the real world.

Feb 11, 2016 at 1:09 AM | Unregistered CommenterDoubting Rich

Doubting Rich -
I read "...aircraft will collectively be airborne for an extra 2000 h each year..." as claiming that total flight time, for all transatlantic routes over a 1-year period, will increase by 2000 hours. [By 2100? I'd have to re-read.] They give 600 crossings per day, or 300 round trips per day. Multiplied by 1 min 18 seconds longer per round trip, multiplied again by 365 days per year, one gets around 2000 hours per year.

Take a small fractional increase (a little less than 0.2%), multiply it by a big base, and you can get a non-negligible change. It's why aircraft engineers work so hard to increase fuel efficiency.

Feb 11, 2016 at 1:55 AM | Registered CommenterHaroldW

@ smith-Smith, Ministry of Silly Flightpaths

'If so, porcine aerobatics are on the horizon.'

Well if pigs could fly, I recommend Harrabin for squadron leader

Feb 11, 2016 at 1:56 AM | Unregistered CommenterEternalOptimist

Quite correct mathematically however.
If covering the same distance the optimum time at any speed is the same speed each way.
If you slow down by x and increase the other leg by x the total time taken will always lengthen.

Feb 11, 2016 at 2:45 AM | Unregistered Commenterangech

This is like when your dad tells you that he walked uphill both ways to & from school, in the blazing heat and blinding snow at the same time!

Feb 11, 2016 at 6:03 AM | Unregistered CommenterDean_from_Ohio

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