Airbus: We should fly like geese to save fuel and CO2

By Bjorn Fehrm

November 19, 2019, ©. Leeham News: Airbus presented a real innovative idea yesterday at the Dubai Air Show to reduce the environmental footprint of civil air transport. In the future we should fly like geese, it saves both fuel and CO2 emissions.

The airframer is starting a program to explore how the geese reduce their energy consumption while flying long distances. They fly in each other’s up-wash. This is to date the most innovative idea in the airframer’s quest to reduce air transport’s environmental footprint. Is it the most unrealistic? Perhaps not.

Figure 1. An A350 follows an A380, flying like the geese to gain from the upwash of the A380. Source: Airbus.

Fello’fly is flying like the geese

Airbus has started a demonstrator program it calls fello’fly. It says:

Airbus’ fello’fly project aims to demonstrate the technical, operational and commercial viability of two aircraft flying together for long-haul flights. Through fello’fly, a follower aircraft will retrieve the energy lost by the wake of a leader aircraft, by flying in the smooth updraft of air it creates. This provides lift to the follower aircraft allowing it to decrease engine thrust and therefore reduce fuel consumption in the range of 5-10% per trip.”

The principle of using the bird ahead’s upwash is shown in figure 2.

Figure 2. The follower bird flies in an upwash from the leading bird. Source: Airbus.

It this realistic? At least as realistic as the inflated expectations around electric and hybrid aircraft fixing the environmental problems of air transport. To gain 10% in fuel burn using these principles will take huge investments in research and development and the results are not guaranteed before we pass the next decade. For the “flying astern” Airbus expects a faster return:

“Airbus is due to commence flight tests with two of its A350 aircraft in 2020. Given the high potential for a positive environmental impact for the industry, Airbus is targeting an ambitious timeline for a controlled Entry-Into-Service (EIS), which is expected before the middle of the next decade.”

Fello’fly problems?

There are many problems involved but also advantages. Let’s start with the advantages:

  • Fello’fly will require investments in enhanced autopilot and modified anti-collision/ADS-B equipment to automate the merging/splitting of aircraft and the fly-astern and make this safely. And Air Traffic Control (ATC) routines need to be set up. But this is limited investments compared to the investment we need to gain 5-10% fuel burn by updating aircraft/engines or the investments in electrical/hybrid aircraft.
  • It will reduce the congestion in the ATC system, for instance when passing the Oceans. Today’s NATS tracks over the Atlantic are getting crowded. In the military, aircraft are handled in two-ship or lager units to alleviate ATC congestion. This can be used for civil flight as well, at least for the cruise segment.

The problem areas:

  • There is an obvious safety aspect with aircraft flying close together. Military aircraft have been flying like this for 100 years. So, it’s nothing new. In the military, it’s done manually but we have the means to automate it in a safe way with today’s civil airliner technology. Every airliner already has the TCAS (Traffic Alert and Collision Avoidance System) and will have ADS-B. This gives the basis for an aircraft merging and place-holding system together with the Autopilot.
  • Aircraft need to coordinate their flights. It can seem like a major obstacle. The question is: it this really needed? Below is a screenshot from the UK’s NATS which shows the traffic over Europe yesterday. At altitude, all aircraft are flying on air traffic highways, after each other. Over the Ocean’s it’s even more pronounced, the aircraft fly in tracks, bunched up after one-another. It’s not inconceivable we can have an automatic merging of adjacent aircraft to fly part of the way as a two-ship, to then split again before the final part of the flight.

Figure 3. The air traffic over Europe yesterday as recorded by UK’s NATS. Source: NATS.

The fello’fly idea can seem far-out. For promising a gain of 5-10% in fuel consumption, and by it CO2 emission, and a reduction in air traffic congestion it’s worth a thorough vetting.

58 Comments on “Airbus: We should fly like geese to save fuel and CO2

  1. Thing about geese, they take turns at flying point. That’s because it’s the one behind that benefits, not the one in front, so that would mean some agreed sharing of the benefit.

    And geese are generally going from the same origin to the same destination, airliners are not, and if they did do that one or both of them would have to go out of their way, diminishing savings.. Wouldn’t it be better to do what geese can’t and have more passengers in a single aircraft than two small aircraft following one another. This would probably mean flying to hubs.

    Mandating the use of turbo-props on stage lengths under 300 miles, and then pushing that distance out every five or ten years or so would be a better way to reduce emissions.

    We’re at an historic opportunity for that, all the fifty seaters, jet and turbo-props, need replacement soon and if 737/A320/E-jets were thrown off the routes where they are most inefficient it would create a hole in the market for 100+ turbo-props. Also, it’s those turbo-props that would most likely be designated the first variants to use hydrogen and/or fuel cells when that technology is ready because the power requirements are lower.

    It would take vision and teamwork between big economic blocks to do it, the EU, US, China. A very big ask. But none of those countries is making a 100+ seat turbo-prop right now and all of them could. I think the market would be rather large.

    • Fauey just said next single isle will be ZE, I’m guessing he means fuel cells, EIS abt 2035. I’ve argued before that BA are between a rock and a hard place as the timeframe will stop them recouping their investment.

      • When all is said and done it will win up 1.5% direct saving and cost 15% to implement.

        As usual the US ala NASA is there, done that, has boxes of research T shirts – Airbus is just making a big song and dance over stuff done by others already, big whoop.

        I am amazed it takes an amateur non aviation professional to tell everyone its 18 wingspans.

        Does this group not follow aviation at all and just parachute in occasionally?

        Took me 30 seconds on a search string.

        • Airbus is using LIDAR to measure the exact position of vortices and has automated much of the process.

  2. Will this be the future of civil aviation in thirty years or so?

    Pilotless planes of different sizes will flock together over the earth great oceans to reach their destinations in the most efficient way possible.

    Also, there is only one important aircraft manufacturer left, it´s name might be Boeinbus or something like this, and there are only three aircraft models available: small, medium and large.

    But maybe the majority of the population in western countries isn´t flying anymore, because of environmental concerns and genderlike uncertainties.

  3. I think it’s a really cool idea, and one for integrated planning into future transoceanic flying… Where aircraft fly in a ‘swarm’ by constantly talking to each other on relative position, direction, routing etc.

    I for one would never get into a self-driving car unless and until they too collaborate and communicate their relative relationship to each other and their surroundings, so action and reaction can be taken collaboratively and therefore safely… Like a very advanced TCAS system. Doing this in the air would actually be safer as there is more room to manoeuvre. O would be inclined to save this kind of swarm-flying to transoceanic flying though. Look at flightradar Transatlantic ‘swarms’ over to the US from Europe in the afternoon, and the reverse in the evening and night… This and these patterns are the ideal use-case for swarm-flying.

  4. Whith ADS-B In and software to keep positions with TCAS IV routines to climb/sink when in problems it is possible in a 10 year certification span. Airlines in EU flying to the big cities in the US could coordinate their T-O times to meet up over NATS area and get their position in the Vee. Just take the Star Alliance aircraft leaving Europe for SFO having the same optimal cruising speed would then team up. The Sky Team Airlines could do the same of adjusting T-O times and mandate ADS-B In.

    • That’s a lot of acronyms, I had to look up all of them. There is TCAS IV ”Traffic collision avoidance system“ which is a sort of aircraft to aircraft interrogator transponder that returns crude bearing, distance, heading speed information and ADS-B. ADS-B is a system in which electronic equipment onboard an aircraft automatically broadcasts the precise location of the aircraft via a digital data link.
      The data can be used by other aircraft and air traffic control to show the aircraft’s position and altitude on display screens without the need for radar. The system involves an aircraft with ADS-B determining its position using GPS. A suitable transmitter then broadcasts that position at rapid intervals, along with identity, altitude, velocity and other data. Dedicated ADS-B grounds stations receive the broadcasts and relay the information to air traffic control for precise tracking of the aircraft. Automatic – Requires no pilot input or external interrogation. – Depends on accurate position and velocity data from the aircraft’s navigation system (eg. GPS).
      Surveillance – Provides aircraft position, altitude, velocity, and other surveillance data to facilities that require the information.
      Broadcast – Information is continually broadcast for monitoring by appropriately equipped ground stations or aircraft.

      The other acronyms are more befuddling. Are both TCAS IV and ADSB accurate enough?

      ADS-B data is broadcast every half-second on a 1090MHz, digital data link.
      Broadcasts may include:
      Flight Identification (flight number callsign or call sign)
      ICAO 24-bit Aircraft Address (globally unique airframe code)
      Position (latitude/longitude)
      Position integrity/accuracy (GPS horizontal protection limit)
      Barometric and Geometric Altitudes
      Vertical Rate (rate of climb/descent)
      Track Angle and Ground Speed (velocity)
      Emergency indication (when emergency code selected)
      Special position identification (when IDENT selected)

      The other acronyms are more befuddling. Are both TCAS IV and ADSB accurate enough?

      • You also have the possibility to have one of the Aircrafts to transmit a GPS position error signal used by receivers nearby to correct their 3D position. This is normally used to have GPS receivers in the vincinity of a ground based station get a much better GPS position accuracy. For a flying Vee-Group “Division” they only need relative accuracy to each other. In such Close formations and with GPS accuracy normally dropping close to the Earth poles laser position communication will probably be mandated as the Aircrafts will also have LIDAR’s to verify the vortex positions to ride at the optimal vortex top position. Aircrafts crossing or getting into jetstreams or crossing traffic remaining vorticies can effect the position and strength of the wingtip vorticies and additional information might be requird in ADS-B In/out

  5. Seems ironic to spend the effort to keep aircraft out of one another’s wakes at take-off and landing and then try to get them into a flight version of NASCAR drafting. And it seems counter to the concept of Direct Flight or whatever the idea to get away from fixed corridors happens to be called. Still, I suppose if one has invested in the hub concept it makes sense to promote this idea.

    • The trouble with that is that dispensing fuel mid flight is far away the most expensive kerosene on the planet. Better to fill up with fuel at ground prices and use it to go all the distance, or even better have a stop over to save money . This is what long distance cargo flights do at an airport on their Great circle route, where possible. ( helps crew flying time and rest periods- even trains work like that so each crew takes it so far and then returns home).
      Military flies this way where possible for larger transport planes, smaller fighters etc just dont have long legs and need in flight refuelings

      • For large Commercial Aircraft lots of mainenance cost is cycle driven, like enginges and landing gears. Staying at optimal Cruise altitude even with a Heavy fuel load is pretty effective. One way to save on fuel would be ground assisted T-O’s allowing the aicraft to Take off at climb Power instead of T-O Power especially at hot days, -10kg/sec * 120sec is 1.2 ton less fuel, Engines hot section parts would like this very much. I cannot claim I have a certifiable solution but in theory together with EASA/FAA it is doable.

        • You bring this ‘catapult launch’ thing up all the time. Has no merit at all and never will. Yet the obvious flaws elude you ?
          As for Takeoff power , thats one of the things modern planes cockpit systems are capable of reducing with the T-O weight, runway length and temperatures etc. Its mostly done for maintenance reasons as max T-O power is a big driver of engine TBO.

          • The one who lives will see… There are TO Power reduction techniques like “Assumed Temperature Take-Off” and others as you input Tamb, runway length, TO Weight… Still the benefit of reduced thrust at T-O for the biggest and most expensive Engines are huge. RR calcultes that the T7000 will benefit alot from its lower max thust compared to the T1000-TEN.

      • The kerosene you burn at the end of a long flight is also pretty expensive. It has been transported 1000’s miles by air. On some long haul routes the refuelling fuel may only have been flown 500-1000 miles.

        Beyond that the aircraft themselves could have a lower MTOW with the savings that implies.

        It may still be an unrealistic concept but I would not dismiss it out of hand.

        • The fuel on a tanker for a midpoint refueling has travelled as well, plus the effect of empty weight of the plane that carries it.
          A single system is far better from an economic point of view, and yes cheaper airfares are there for people who dont mind one stopover, not really that many as Icelandairs traffic numbers can attest.

  6. It’s an interesting idea, but even if you can iron out the technical kinks, seems like it would be a niche opportunity. Would the lead aircraft induce turbulence on the following aircraft?

    Mandate the use of non-fossil derived kerosene at steadily increasing levels over a couple decades. You’d expect the non-fossil fuel economics to improve steadily once there’s a guaranteed market for it. After many decades, solar panels have gotten to the point that they’re economic. We may or may not get to that point with non-fossil kerosene, but burning the fossil stuff is killing us, so if we end up paying a premium, that’s what we’ll have to do.

    • There is no climate crisis, the world is not ending, we have more than 12 years to ac but I understand that people have anxiety over it. Aviation is 12% of transport emissions, 2% of global missions. Airlines spend 3x more on fuel than they do on new aircraft. There is no need to mandate anything because the price signals are already there. Any actions should be to assuage concerns of the public. I’m happy for airlines to plant trees and do some reafforestation but its better to spend the money elsewhere where it will be far more effective. Synthetic Hydrocarbons are a quite plausible idea. The amount of energy required to extract 1KG of CO2 from the atmosphere is down below 0.25kWHr/KG (Kerosene has 11kWHr/Kg) and this CO2 can be reacted with hydrogen over catalysts to make fuels. Its as efficient as making cryogenic hydrogen (more like 70% efficient) Unfortunately some of the same people that are as alarmed over AGW also stopped the roll out of Generation IV and V reactors (Bill Gates is putting money into it). The price of Green electricity is very high. If a Litre of kerosene has 8.5KWHr of energy it would require about 12KWHr to make fuel on top of that add about 30% for the equipment. Synthetic hydrocarbons will cost as much as petrol from the bowser so your avgas will cost about $250/barrel. The good news is it can be made anywhere and transported. I would say maybe use it for 2% of a flights fuel.

  7. This has been talked about for years. At least I’ve read ‘blue sky’ articles discussing it at least back last decade, probably last century.

    It also seems an odd idea to be highlighting given that “route free airspace” is just becoming a reality and surely has greater potential for reduced consumption through more direct, aircraft specific routes for long haul while in at least their home EU market Commission policy aims to switch air travel to rail travel for journeys under 1000km.

    But, perhaps on certain high density routes it may be worth looking at.

  8. What kind of proximity are we talking about here?
    ( nothing mentioned in the text .. )

  9. As far as reducing carbon emissions it doesn’t seem worthwhile to spend much time trying to get a 10% reduction when total air traffic has historically grown by 3.6% on average and was over 6%. So while this might be valuable in the short term for airlines it really doesn’t address the underlying problem.

    The airline industry is going to need a paradigm shift, if we are not going to go back to sailing ships across Atlantic and Pacific.

    I do remember the plans for Hydrogen powered planes during the 1972 energy crisis for instance. That seems the easiest way to retain almost all current technology.

    • That is quite a bit further apart than I would have derived from “how the birds do it”. i.e. flying in close (~~same magnitude as bird size ) formation.

      Any ideas around how much energy birds are able to leech from their upstream “wingbird” ?

    • The Airtransport Industry is willing to kill for small single percent improvements.

      Think again if 10% will really be “shrugged away” without further thought.

    • Aircraft and Engine manufacturers happily spend almost $1bn per % fuel reduction as you reduce Aircraft operating cost and increase range. So 10% is huge.

  10. I’m hearing a certain A380 is going to be converted to fly an engine on hydrogen so it’s coming around full circle. Maybe the saviour of the plane with large tanks and zero emissions and no need for the flock…………..

    • The 1990 there were proposals to build. Do 328 Jet with large cryogenic hydrogen tanks outboard of the engines. Hydrogen for the same amount of energy is 3 x the volume of jet fuel but 1/3rd its weight. An A300 with a cryogenic hydrogen tank running the length of the aircrafts top was also proposed. It wouldn’t be a big problem to build the cryogenic hydrogen infrastructure at key airports. I favour synthetic hydrocarbons.

  11. Sailing ships!:

    Save 100% CO and 100% efficient, Greta travels that way.

    sigh: of course is they are slow and don’t stick to schedules well and all those sea sick passengers.

    • Sail ships aren’t slow ( with enough wind. The Flying P Liners from the beginning of the 20th century used to do ~18kn).
      What made them uncompetitive are the scheduling uncertainties.

      • Even at a sustained 18 knots we’re talking a week to cross the Atlantic. And how often could they sustain that speed? As you pointed out, their scheduling uncertainties make them uncompetitive vs steam. Of course even steam/oil powered ships with their predictable schedules were themselves unable to compete with aircraft.
        So a return to the nineteenth century mode of transoceanic travel would be a rather significant reset indeed. And a 21st century wind ship is still going to need power for onboard functions. Lighting, cooking, climate control, and waste treatment. Can’t just dump it overboard untreated any longer and the ship is going to have several hundred people generating bodily waste over that week or more. Doesn’t seem likely they could store it until landfall to be treated ashore.

      • It wasn’t speed which killed them, it was navigability in places like Suez+high labour costs

        • Uh guys, you know the wind blows in different directions?

          Slow is an integration of stuffed for progress as its turned the wrong way and all that zig zagging and if lucky run off shore when things go South?

          • Effectively they weather routed, what people don’t realize is ships still weather route, you can burn a hell of a lot of fuel, loose days and suffer loads of weather damage trying to fight mother nature. It’s just like aircraft in that respect, except they don’t have deck cargo to smash.

          • They weather routed where they could, many place and times no choice.

            Ships now route modify not weather route.

            You can only go so far off track and then you accept the least worst option.

      • The poor Germans were still using Wind Jammers until the 1950s to carry guano super phosphate from South America.
        Nevertheless it’s not worth it. An 8000 TEU ship (8000 containers) will burn 150 tons of bunker oil per day at 21 knots. So the 3000 nautical miles across the Atlantic will burn 900 tons which is about 115kg per container. Drop the speed to 18 knots and the fuel burn drops to 100 tons/day but journey time goes up 15%.

        • Regular sailings from Aus until WW2 destroyed the fleet, bombed or 6 years rotting in port.

  12. I’ve thought about this a little more; say a Lufthansa A320 and an Emirates A380 take-off at the same time on similar track for Munich and Dubai respectively. It may be alone that the A320 could make FL390 but the A380 at that weight could only make FL350 (I’m guessing, these are not real figures). There could be a two-fold benefit available to the A380 if the A320 took the lead and enabled the A380 to ascend to the higher altitude and to benefit from the updraft from the wing vortex of the A320. It would reap the benefit in climb and cruise of both lower thrust and a higher initial cruise altitude. When the A320 descended the A380 might be at a weight suitable for FL390 and continue on its way, perhaps pairing up with another aircraft on the way.
    I can’t see it the other way round, the A320 following the A380 because the A320 might well do better (and go faster) flying to a higher altitude by itself.
    It might be a really useful technique for ultra long-range flights – London to Sydney for instance.

  13. Tax the fuel to the same degree as other forms of transport and the gains will come,make them care. Obvious improvements are, stop tankering fuel and pointlessly transporting bottles of duty-free whisky.
    Any government thinking about this should read o’leary’s comments about the lack of the MAXs fuel economy making some routes unviable, so about 15 % would be a good starting point.

    • I think you’re wrong on that buddy. There are usually two “taxes” applied to fuel. First is a GST or Goods & Services Tax (or VAT). This is the general tax that is applied to a good or service at the time of purchase by the final consumer. It is put into consolidated revenue to be misused as the Government sees fit. GST doesn’t apply to commercial jet fuel because GST is applied to the ticket price and therefore as always is to be paid by the final consumer. The ticket sale prices therefore incorporates the cost of the fuel plus the value added by the airline. You don’t tax your inputs.

      The other “tax” is Excise is which applied to particular goods at the time of production completion, in this case at the oil refinery. Petrol Excise is meant to compensate for the costs of roads and infrastructure such as bridges. Aircraft don’t use roads and bridges (which cause hideous environmental destruction.) so the excise is much reduced for Jet fuel. Airlines pay airport fees and passenger fees to pay for the airport use so excise isn’t needed to support the Airport and its operations. Incidentally the road in front of your house costs $1 per square meter per year to install and maintain and is covered by the rates you pay to the local country or council. Arterials roads are easily paid for by excise. Farmers don’t pay excise on their diesel because their tractors don’t (seldom) use roads and bridges and you don’t want expensive food. They are usually given license to buy special low excise diesel with a dye that will stain the engine so it that may only be used in tractors, generators and harvesters, if you get caught using it in your car town car you will pay a fine. If I go to a remote mine site in Western Australia, say an Iron Ore mine, you will find vast amounts of diesel used for the mining vehicles such as tucks and excavators which often weigh upwards of 700 tons as well as in generating power in gas turbines and diesels for running the minerals processing plant. Those mine sites will pay excise in many case but they are given a rebate at the end of the year. They don’t use public roads. You don’t tax your inputs, ever. Its the same everywhere. Incidentally you shouldn’t pay excise for the fuel to fly to that mine site instead of driving on the dirt or poor quality road.

      My studied opinion: there is no climate crisis, its hype, the world is greener and there is more forest now since 100 years ago. The oceans haven’t risen. cO2 increase may even have increased plant growth. The temperature increase of 1.8F are only as measured from the 60’s and are disappear if one counts the heat waves of the 1930s and 40s.

      Aviation emissions are 12% of transport emissions but only 2% of global emissions and airlines spend 3x more on fuel than they do on purchasing aircraft. The incentive to cut fuel consumption are already there and they are very strong. Taxing fuel would destroy the industry and since the industry is achieving fuel burn reductions of 0.7%/year (7% decade) just in the engines it is not called for. It will probably destroy the airliner business and reduce the rate of progress.

      Rail is a hideous form of transport. It separates local communities and most rail journeys must begin and end with a car. Instead walking 500m you drive 3km to cross a rail bridge to get to the other side. Rail destroys vast swathes of land, a 30m wide strip of land, denuded of trees and vegetation that impedes animals and people from crossing. The rail, fencing, ballast, earth works, bridges take enormous sums of energy to build and maintain. It’s instance. The maintenance activates, all the people working on it.

      It’s my observation that people with a left kind of mindset don’t tend to think of taxes as something that must be applied rationally only profits or as a excise fee on use of community resources and never on inputs or investments. Its a capricious of social manipulation. If you are a academic, politician of the left or bureaucrat tax revenues increase your power by sucking resources from the economy and the workers of industry to you. Taxes to some people means “free stuff”. A crisis like Anthropogenic Climate Change is like all crisis to be cherished and exploited to promote the change you want. EG carbon credit trading if you are a certain bank.

      • William, your considered analysis of the effects of rail is tad overblown
        ‘ Rail destroys vast swathes of land, a 30m wide strip of land, denuded of trees and vegetation that impedes animals and people from crossing….The rail, fencing, ballast, earth works, bridges take enormous sums of energy to build and maintain. ” That describes roads too, but ignores commuter rails capacity compared to say a 4 lane motorway.
        The rail lines coming into Newcastle NSW the worlds biggest coal export port with around 150 mill tons per year on around 60 coal trains per day up to 1.5km long each. Mostly 2 tracks with 3 in some places and where there is 4 , two are exclusive for coal.
        The Paris Lyon TGV high speed rail line, double track is 400km but only uses half the land area of Paris CDG airport. The capacity is 240 trains per day , many double decker ( called OuiGo, mimicking budget LCC with online only fares and outer suburbs stations) with new upgrades allowing 14 per hour each way at peak times. They too like airlines are wanting higher capacity on routes

      • “My studied opinion: there is no climate crisis,.:”

        ( actually waiting for some professionals bringing a Straitjacket).

  14. I tell you, this is a fascinating concept. That would be a sight to see on a clear day on the ground, or up at 38,000 feet.

  15. You really haven’t studied very hard, have you? Air travel isn’t actually that bad per mile (assuming that you are crammed in efficiently and aren’t taking too much crap with you) the problem is the amount of miles that it makes it easy to do cheaply.
    A lorry pays far more tax on its fuel than an aircraft.

    • About 2.3liters/100km (about 100mpg) in the most efficient single aisles. So if you are going 1000km it is better to fly than drive unless there are 2-3 people in the car.

      ** Now of course a bus is a totally different proposition. A filled greyhound will beat them both probably by an order of magnitude.

      ** But of course if one is concerned about carbon output the really answer is not to travel 1000’s of km in the first place.

      ** This leaves out the the carbon cost of maintaining the roads/rails or aviation infrastructure.

  16. ROFL

    Wouldn’t that take incredibly precise positioning to avoid rolling and turbulence, complete with instant anticipation signal from the lead airplane when it hits unexpected turbulence?

    IMO it’s another pandering exercise to keep politicians away from interfering with great advances for human life.

    (The scam that humans can ruin earth’s global climate.)

  17. I wonder if this could make urban mobility solutions long distance ones? Instead of a flying Uber to the airport, it could join a stream of Ubers before dropping to its final destination. By 2050?? it might be the way to go for a 1000km trip.

    • The urban mobility problem has been solved. Visit London, or other large dense cities with subways.

      “A developed country is not a place where the poor have cars. It’s where the rich use public transportation” – Gustavo Petro

  18. I like Petro, wish he’d won the last election.
    Unfortunately Bogota was recently rated 3rd last amongst the major cities for public transport, not Petro’s fault. My intention with this post was to suggest that current to develope urban mobility flights might one day use the ‘like geese’ concept for longer distances.

  19. All the things we have to come up with to confuse the environmentalists, while producing / flying more and more aircraft, 75% for fun..

  20. And are they talking about still well behind the lead aircraft, whereas refueling and military formations are close?

    BTW, note that Canada Geese switch leads to avoid overtiring the lead. Mebbe the lead airplane could get PetroPoints datalinked to it from followers to pay for the fuel benefit it is not getting. :-o)

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