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My story takes place on an Earth-like, inhabited world that is far larger than Earth, has roughly 110% of Earth's gravity, and has unusually high (and generally unexplained) EM emissions permeating its atmosphere sufficient to disrupt radio transmissions beyond a few miles.

Humans from earth have begun to settle the planet, primarily big corporations seeking to exploit the planet's rare natural resources. Wheeled transportation between settlements isn't very practical due to the great distances between settlements.

My story revolves around high speed ground-based transports, so I'm looking for plausible reasons or obstacles that would help explain why traditional jet/rocket/prop-based air travel is not practical.

Important notes:

  • Atmospheric pressure at the surface is roughly similar to Earth's (another problem I'm still working on), but with a higher ratio of nitrogen to oxygen. Mean Climate, radiation levels, etc. are also comparable. Much of the time, humans can survive outdoors on the planet just fine using rebreathers, although both the daily and seasonal temperature variance tends to be a bit more extreme than Earth, and the days are shorter.

  • The first settlements on the planet were exploratory, inhabited originally by scientists and supporting bureaucracy & infrastructure. These early settlers discovered trace quantities of a previously unknown compound with certain highly valuable properties. This gave rise to multiple competing private interests investing heavily in tracking down concentrations of the stuff large enough to make harvesting it worthwhile, despite the distance between said deposits and other environmental challenges. Many such clusters have been found but tend to be very far apart (and a single corp tends to claim a large area whenever a cluster is discovered in hopes of finding more).

  • The ground-based transports actually levitate in a manner similar to a hovercraft, but using a hypothetical thrust technology (which is dependent upon the same resource everyone's hot for in the first place). This gives them enough lift to easily clear obstacles like rocks and shrubbery, and even water -- and taller obstacles, too, for short periods -- but not enough to actually fly. A variety of more conventional engines are used to provide directional thrust.

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    $\begingroup$ You can have high levels of dust, and with some handwaving keep it higher off the ground. This would make high speed air travel problematic, if not unfeasible. $\endgroup$
    – Alexander
    Sep 21, 2017 at 18:45
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    $\begingroup$ If wheeled transports aren’t practical and rocket/jet/prop propelled vehicles are excluded what sort of high speed ground transport are you considering? $\endgroup$
    – Slarty
    Sep 21, 2017 at 18:52
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    $\begingroup$ I'm rather with @Slarty on this, actually; why is distance between the settlements a major problem? Why is fast travel between settlements even necessary? If you are a corporation sending people there to do mining operations (even if only by operating machinery), it'd make much more sense to mostly stay in one area, then move on to the next one -- not commuting back and forth. If you can tell us the motivations for these people to have high speed ground-based transport in the first place, we might be able to give you better answers as to why air travel wouldn't work. $\endgroup$
    – user
    Sep 21, 2017 at 19:07
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    $\begingroup$ @Slarty OP said rocket travel is not practical, not that it isn't possible. Rocket travel is hugely expensive in terms of energy; it's something you'll reasonably want to avoid unless there really is no other way. $\endgroup$
    – user
    Sep 21, 2017 at 19:41
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    $\begingroup$ One word: Pterodactylus. $\endgroup$
    – kikirex
    Sep 22, 2017 at 11:18

20 Answers 20

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I'm looking for plausible reasons or obstacles that would help explain why traditional jet/rocket/prop-based air travel is not practical

Killer pigeons.

Well, not exactly your ordinary columba livia domestica, but pigeon-analogues nonetheless. They live almost everywhere, breed like crazy, and luckily, unlike their Earth cousins, dislike the noise and smells of human cities and keep to the brush, fields, and undergrowth.

They're mostly harmless, except that they have this reflex - perhaps evolved to deal with very large predators, now understandably extinct - to swarm and attack whatever flies and is sufficiently larger than them.

They will roost on an airship and tear it to pieces in a killing frenzy, they'll overload the most powerful armored drone, and they will kill themselves smashing against a landing shuttle at the highest speed they can attain. And they will foul all kinds of enclosed or non-enclosed propeller with their pseudo-feathers and down and blood, choke jet engines with their bodies, and nine times out of ten they'll even succeed in killing anyone that succeeded in ejecting unless they reach the ground quickly enough to make the attack stop.

In the country, boys will dare one another to fly kites, to watch clouds of shrieking berserkers tear them to pieces.

Poisoning the pseudo-pigeons is impossible without covering the planet with poison; gengineered pathogens risk destabilizing the whole ecosystem; introducing predators is hopeless because they'd be swarmed under; the best that can be done is flying at night, losing one plane in ten, which is totally unaffordable, or using armored, slow airships, which are even more uneconomical; or using orbital shuttles that take off at high acceleration using ground-based lasers, and perform combat-drop landings; which is the most expensive option of them all, even if it is done to land tech, outworld supplies, and personnel since it is, after all, the only way.

Once an experimental project aiming to teach them not to chase fliers, using hundreds of large rocket-propelled cut-out shapes, floundered against the hard fact that the alien pigeons were just too stupid to learn, and attacked the thousandth fake plane with the same reckless abandon of the first, Earthmen decided to leave the alien skies alone.

So, railway it is.

Can't live with them, can't profit without them

Albeit dubbed pigeons because of size and general shape, our critters aren't really pigeons; to be sure, they're not Terran birds either. They don't behave like ones, nor do they reproduce the same way. The passenger pigeon was adapted to its environment, but vulnerable to anthropization. The main vulnerability was the existence of nesting colonies. Disrupt the colony, extinguish the species. Our critters are solitary and r-strategists, more like insects than birds, and have managed to monopolize the air; the ecosystem has adapted so that they are the only long-range pollinator species, the main source of protein-analogues for a host of scavenging organisms that also improve the soil (okay, worms), and several arboreal species have co-evolved so that their seeds are now only viable after passing from a pseudo-pigeon's digestive tract (presumably quite far from the parent organism). In short, not only would removing the crazy psycho-pigeons be exceedingly difficult, it will involve a long-term ecological nightmare.

Which we can't afford because it turns out that the precious compound found in the soil is in all likelihood a breakdown product of some kind of complex polyterpene associated with some of those plants' pseudo-bark. The exact chemical makeup and synthesizing pathway not having been successfully investigated yet, much less reproduced artificially (and nothing guarantees it won't be horribly expensive anyway), the various interests on the planet simply do not dare meddling too much with the ecosystem.

What they can do (and do) is harvest reasonable quantities of pseudo-bark from promising copses, and send them by rail to the processing plants.

Railways are deployed by track-laying robots and are reusable, light and sturdy enough to go practically everywhere. It would be possible to prepare covered, protected airstrips where a computer-controlled plane would enter at high speed and leave at high speed, but it would cost much more and not be as flexible as rails. The impossibility of long-range communications with planes (and of using radars) also reduces their appeal. What would really be useful is helicopters, but those are out of the question: they'd need to fly slowly and from, or to, pigeon-rich woods, exactly the thing one shouldn't do.

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    $\begingroup$ Actually, this idea has promise. Like, crazy amounts of promise. You've put me onto something here, @LSemi. $\endgroup$
    – Brian Lacy
    Sep 22, 2017 at 2:48
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    $\begingroup$ At one zapper per pigeon, this is still pretty expensive. If you're set out to genocide killer pigeons (but xenoornithologists will hate your guts in that case), there are better options - such as men with guns. $\endgroup$
    – John Dvorak
    Sep 22, 2017 at 9:49
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    $\begingroup$ Potential workaround to this: Decoy planes, low cost unmanned drones which are launched around the take off and landing sites to distract the killer pigeons while aircraft take off/climb to a high enough altitude for the pigeons to not notice them and again when descending/landing. Could be that the drones are expensive enough that it's only economical to launch them when sending ships into orbit/beyond for supply runs. $\endgroup$
    – RobbG
    Sep 22, 2017 at 10:48
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    $\begingroup$ I'm considering using a much-expanded version of this to solve my problem. No killer pigeons (sorry @LSemi!), but it gave me the idea that the skies on my planet are rather like the oceans on earth -- teeming with a grand variety of ultra-light, highly buoyant, permanently airborne critters. Some hostile, potentially (flying sharks, anyone!? j/k), but most simply going about their business until they get sucked into a jet engine or prop. No good for the critters, and no good for aircraft, either. $\endgroup$
    – Brian Lacy
    Sep 22, 2017 at 15:18
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    $\begingroup$ On that planet, guano is likely to be an important resource for agriculture (to be transported on railways and ships, needless to say). $\endgroup$
    – fralau
    Sep 24, 2017 at 8:34
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Unpredictable weather with lots of microbursts, wind shear, tornados, and other unfavorable winds.

Wind shear is one of the most dangerous things for an aircraft. Thankfully they are generally rare, on Earth. If flying isn't a question of if there will be a wind shear, but how many there will be, flying wouldn't be something that you'd want to do.

Very low temperatures and ice clouds to cause constant wing icing.

Airplanes have wing deicers, but at some point the icing can be so bad that they can't compensate.

Treacherous terrain, which would make emergency landings impossible.

You don't want to fly if any attempt at emergency landing is going to be fatal. High mountains and other dangerous terrain would be a big problem if it covers the entire surface, especially if the weather or other things make emergency landing a higher probability.

Combine this with unpredictable weather and it gets real iffy. No one wants to be slammed into a mountain by a downdraft or fly into a cloud that's full of rocks.

Huge flocks of birds or other flying creatures that would foul engines.

If there are flying creatures that are either accidentally or purposefully suicidal, then flying would be basically impossible.

Extreme heat.

Heat can ground an aircraft just as easily as cold.

Fuel shortage.

Flying can take a long of energy, and so not having a dependable, clean, fuel source would be a big problem. If the planet has no petroleum, and bio fuels aren't being produced fast enough, then that would make flying difficult.

High solar and atmospheric radiation

The higher you go, the more radiation you receive. In the event of a solar flare, there can be a big spike in radiation. If this planet had a very active star then that could become a big problem for any aircraft without shielding, and shielding is very heavy. Whatever causes the atmospheric radiation could also be the source of the heavy EM interference.

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  • $\begingroup$ I was also going to answer fuel. With 110% gravity, flying is going to be very costly and a lot more inefficient than here on earth. You'll need more fuel to go the same distance. Aircraft can only hold so much fuel, even with auxiliary tanks. If you have to carry twice the fuel to go half the distance and that fuel takes up the space paying passengers would sit, it just isn't economical. Since it's mostly corporate activity on the planet and corporations are fixated on the bottom line, simply explain that flying is possible, but not economical and reserved for the direst circumstances. $\endgroup$
    – Steve Mangiameli
    Sep 21, 2017 at 20:04
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    $\begingroup$ @SteveMangiameli "With 110% gravity, flying is going to be very costly and a lot more inefficient than here on earth." Um, no. A 10% difference isn't enough to make the difference between flying being practical and not; other factors, including availability of fuel, however, might (as discussed in this answer). That's the difference between Earth's 9.8 m/s² and this planet's 10.8 m/s²; that's a somewhat noticable difference, but hardly a major change. Do note that OP didn't state 110% greater gravity, which would make for 20.6 m/s² which may very well cause much greater difficulties. $\endgroup$
    – user
    Sep 21, 2017 at 20:45
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    $\begingroup$ Pretty solid answer, except that rugged, mountainous terrain would also be a barrier to ground vehicles. $\endgroup$
    – bgvaughan
    Sep 21, 2017 at 21:17
  • $\begingroup$ @SteveMangiameli With respect to gravity, the behaviour will be the same as flying in a constant 2g turn. It's a few years since I worked in the industry, but I'd guess at fuel use rate not more than 50% higher at 2g - essentially higher lift induced drag, but the rest remains the same. This is the same as the difference in fuel efficiency for long range commercial jets between today and the 1980s - air travel was certainly less commonplace, but it wasn't completely out of range of ordinary people. $\endgroup$
    – Pete Kirkham
    Sep 22, 2017 at 9:46
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    $\begingroup$ @bgvaughan Not necessarily. bulldoze a road or bed for rail, bore a tunnel, whatever, and you only have to do it once. It's a bit of work, but if you were going to put in a new road across the flat prairie you'd have to do it too. You could prepare a few emergency air strips the same way, but you can't guarantee that you'd be close enough to one when you need it, especially if the ground is really mountainous. Combine this with any of the other possibilities and things would get real messy real quick. $\endgroup$
    – AndyD273
    Sep 22, 2017 at 17:19
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The air is about 45% less dense than it is on earth.

Aviators know that it's not the wings that give you lift, it's the air underneath them. With a 45% reduction, it's equivalent to about 6km above sea, or 2/3 of the way up mount Everest. enter image description here This would obviously come at the price of needing to bump up the oxygen content of the air for humans to live, but it's entirely possible.

Some may see a hole here, and that's that the average Jet cruises at 11.89km. To combat this, one could say that it's very unlikely that Jet engines would be even remotely close to being discovered without the good ol' propeller plane first.

The biggest weakness of this explanation is that rockets would be MORE efficient than if the atmosphere was less dense. This is true, and I suppose rocket-based aviation is entirely possible, and not unlikely...

The place i think this explanation stands out is that unlike bad weather and shortages, this is perfectly fine for land vehicles. It's a grim fact, but when people who commit suicide via car exhaust in an enclosed area are found, their cars are empty of gas, meaning that the cars ran long after the people did.

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    $\begingroup$ 2/3 of the way up Everest would pretty much eliminate helicopters and slow-speed airplanes. Jet airplanes would still be possible, but you'd need an absurdly long runway to take off with any reasonable cargo. $\endgroup$
    – Mark
    Sep 21, 2017 at 20:57
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    $\begingroup$ @kikirex not quite. They'd be able to operate; but, like typical dirigibles, they have a maximum altitude they can reach before the pressure difference (due to the lack of air pressure outside) becomes greater than the stress limit of the balloon's cover. In an atmosphere such as this, that maximum altitude will drop extraordinarily. $\endgroup$
    – KareemElashmawy
    Sep 22, 2017 at 15:03
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    $\begingroup$ Aviators know that it's not the wings that give you lift, it's the lower air pressure above them. ;) $\endgroup$
    – Eric Duminil
    Sep 22, 2017 at 18:54
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    $\begingroup$ @kikirex, certainly. At sea level, a cubic meter of hydrogen can lift 1.2 kg. A 45% reduction in pressure will reduce the lifting capacity in proportion. Hydrogen and helium balloons will still be possible, but with a greatly reduced cargo capacity (weather balloons, yes, freight zeppelins, no); hot-air balloons probably won't be able to get off the ground. $\endgroup$
    – Mark
    Sep 22, 2017 at 19:11
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    $\begingroup$ @Thomas things tend to explode with pure oxygen $\endgroup$
    – tuskiomi
    Sep 22, 2017 at 20:16
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Okay, I'm going to take a stab at this, and run the risk of having to delete this answer if it turns out my assumptions are wrong. Given what's in the question thus far, though, I think that an obvious choice would be the fact that...

It's much easier to transport large amounts of material on ground than by air.

Both ventsyv and tuskiomi discuss this in light of atmospheric pressure, but I think there's a bigger issue at play: Having to lift stuff to move it often ends up requiring more energy than just moving the same stuff.

Given that this is about humans colonizing an alien planet, I think it's safe to assume that they have access to most things that we take for granted today. Maybe not ready access, but access no less.

If you can clear out a ground path sufficiently to transport things on the ground, and maybe even build even a rudamentary "highway" system (which does not need to involve paved surfaces; this could be a railroad highway system, for example), then going a few hundred kilometers per hour is certainly practical, especially if the atmosphere is thinner than Earth's (resulting in less drag); and you don't need to spend energy to lift it all the way aloft just to bring it back down again.

There's a reason why lots of Earth transportation is done by land or sea, rather than air, unless speed is of the essence (at which point you accept the higher cost).

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    $\begingroup$ The faster you go, the smoother the roads need to be. At 10 km/h, a rough track carved by a bulldozer is viable; at 300 km/h, an inch-high bump was sufficient to cause a Bugatti Veryon to lose control. $\endgroup$
    – Mark
    Sep 21, 2017 at 21:00
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    $\begingroup$ @Mark True for cars/trucks but can be avoided with rails or hovercraft-like technology. $\endgroup$
    – Till
    Sep 22, 2017 at 8:42
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    $\begingroup$ @Mark True enough as stated, but I wasn't thinking only of paved roads, as Till noted. And of course that circles back to the question of why one would need to go that fast in the first place. $\endgroup$
    – user
    Sep 22, 2017 at 11:54
  • $\begingroup$ It sounds like the way to move stuff over land, then, is with high-speed trains. Possibly of the maglev variety depending on other requirements... or it might not matter. Which is pretty much what the US did when it had to move large quantities of resources between two oceans before technology advanced. Additionally, we still prefer to ship things by boat, and typically only air freight things if timing is important. $\endgroup$
    – Ellesedil
    Sep 22, 2017 at 18:01
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    $\begingroup$ @Ellesedil before technology advanced? Most durable goods in most Americans' homes moves by rail. There goes a bunch! The ship-train-truck container business is huge. A big containership can unload 30 trainloads of containers, and off they go. It's often cheaper to ship to L.A. and go rail to NYC than sail the boat clear 'round. $\endgroup$
    – Harper - Reinstate Monica
    Sep 24, 2017 at 21:38
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Frequent volcanic activity effectively grounds all current aircraft.

The volcanoes could be located in specific region (along a tectonic plate boundary, for example) that does not endanger settlements. If the eruptions were frequent enough (ten or so per year) they would produce a semi-permanent smog of high-altitude ash that might be unnoticeable to humans at ground level thousands of miles away (as was the Eyjafjallajökull ash cloud) but which would make air travel impossible.

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    $\begingroup$ Volcanic ash affects jet engines really badly. Other types of engine may be less affected, so it would depend on the type of hardware available. (it is really abrasive though, so really not good to fly though regardless of engine type if you don't want to be replacing your cockpit windows after every flight) $\endgroup$
    – Simba
    Sep 22, 2017 at 12:41
  • $\begingroup$ I was going to post something similar so +1 instead. $\endgroup$
    – Michael Richardson
    Sep 22, 2017 at 13:16
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    $\begingroup$ I think Oscar nails it. The 2010 eruptions of Eyjafjallajökull and the 2011 eruption of Grímsvötn shut down much of the air travel in Western Europe. The dust absolutely destroys jet engines. A few ongoing eruptions could shut down air travel on Earth as well. volcanoes.usgs.gov/volcanic_ash/… $\endgroup$
    – gwally
    Sep 22, 2017 at 20:22
  • $\begingroup$ Here are some choice quotes from the captain Speedbird 9 which flew through a cloud of volcanic ash from the eruption of Mount Galunggung. "Ladies and gentlemen, this is your captain speaking. We have a small problem. All four engines have stopped. We are doing our damnedest to get them going again. I trust you are not in too much distress" They managed to restart three and landed but the landing was "a bit like negotiating one's way up a badger's arse." $\endgroup$
    – chx
    Sep 22, 2017 at 22:04
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No fossil fuels

Fuel availability is a big deal.

If the planet doesn't have a good supply of fossil fuels, then everything you do on the planet will need to use other fuel sources. Solar, nuclear, whatever.

All of these technologies will strongly penalise air travel.

Electric cars (and trucks) are a perfectly sensible solution and even today can be built with sufficient range to cross a continent.

Electric aircraft, on the other hand are not generally a workable solution. Giving them sufficient batteries to fly for a useful distance simply adds too much weight. You might get short range quadcopters powered with batteries, but you won't get long range airliners.

Hardware has to be shipped from Earth

Another idea is to realise that this colony is still in its infancy. Sure they're building up their infrastructure, but they don't have the resources or local expertise yet to build aircraft factory so if they wanted to fly, they would have to transport the aircraft from Earth.

That's simply not practical. Transporting bulky items between planets is expensive. They'll ship the hardware that they really need, but aircraft would not be seen as a necessity. Land vehicles are smaller and easier to transport when kickstarting the colony, they're easier to maintain in those early days, and they're also easier to build locally once you start building local manufacturing capabilities.

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    $\begingroup$ Two perfect points. $\endgroup$
    – Cem Kalyoncu
    Sep 23, 2017 at 14:32
  • $\begingroup$ Good points, but nuclear aircraft are more practical than you might expect. Both the US and USSR designed and tested them during the Cold War, but they were never needed... on Earth, at least. If your colonists have fusion power, it's even more practical. See en.wikipedia.org/wiki/Nuclear-powered_aircraft $\endgroup$
    – fluffysheap
    Sep 24, 2017 at 7:10
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    $\begingroup$ @fluffysheap - I'd tend to rule out nuclear aircraft on grounds of safety; one accident and you're looking at a very difficult cleanup. $\endgroup$
    – Simba
    Sep 25, 2017 at 7:53
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A very plausible explanation is that the atmospheric pressure is very low thus providing very little lift. This is compounded by the higher gravity. To counter that your airplane needs to have bigger wings (which means heavier) and fly faster. At some point the whole thing becomes impractical.

Another explanation is to have atmosphere with high level of ash. Ash can damage the engines thus making flying very dangerous.

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  • $\begingroup$ In order to have a sufficiently high partial pressure of oxygen at the surface, particularly with a high ratio of nitrogen to oxygen, there must be something close to normal Earth pressure at the surface. Given that we have a very large planet with 1.1g surface gravity the gravitational gradient will be lower than on Earth and so the pressure gradient will also be lower. I don't think low air pressure can work. $\endgroup$
    – Alchymist
    Sep 22, 2017 at 22:07
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The most obvious answer I can think of is an out of control satellite air defense system that shoots down any moving object above a certain height.

The military installed the system but something went wrong and now it doesn't differentiate between friend and foe and shoots down everything above X metres above the ground. They haven't fixed the system because nobody can get into space anymore and the satellites are hardened against being shot down.

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  • $\begingroup$ I love that that's the most obvious thing you can think of. So hurricanes and volcanoes are way more outlandish?... $\endgroup$
    – Oscar Bravo
    Sep 22, 2017 at 9:37
  • $\begingroup$ @OscarBravo Indeed, it's a good relatively obvious answer for a newly colonized world somewhere in space. Planes fly through hurricanes today, and you wouldn't want to live next to a volcano so wouldn't need to fly through them anyway. $\endgroup$
    – Xen2050
    Sep 22, 2017 at 12:14
  • $\begingroup$ @Xen2050. Lots of people live close to volcanoes. $\endgroup$
    – TRiG
    Sep 22, 2017 at 16:39
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    $\begingroup$ This setting was used in Woken Furies Harlan's World is surrounded by "orbitals" that were created by "Martians". The Harlan's World orbitals are programmed to destroy any object of sufficient technological level flying above ~400 meters altitude and do so with high-energy beam weapons known as "Angelfire". $\endgroup$
    – chx
    Sep 22, 2017 at 22:11
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A lot of suggestions here, apologies, I didn't read them all so if this is redundant just delete it.

I'm a big aviation buff, so I think I have a simple, easily implemented (not distracting) answer. It's actually quite simple: Make it so that visibility is never longer than half a mile.

In real life you need, at very least, a mile for what's termed "Visual Meteorlogical Conditions". Those are the conditions that are required to fly without the aid of navigation equipment. There are a lot of reasons for this, but I won't go into it here. Just read the article I linked and you'll understand ;).

Further, since the planet you describe can only allow radio signals to go a mile or two, there's really no way for aircraft to navigate without seeing outside the plane. All modern navigation equipment is radio based in some form, high EM would make that highly unreliable.

The only backup to that system would be to navigate by the stars, but, if the atmosphere only allows for a half mile of visibility..... You can't see those either.

Granted, there are probably ways to get around this (I mean, back in the old days people flew long routes by looking for bon fires to guide them.) But I think it's a sufficiently large problem that rail transport would be considered significantly cheaper by most transportation authorities.

On top of that, most transportation consumers (who generally fear flying to begin with) would probably be pretty scared of flying in a plane being guided by, basically, bright lights... It would drive down revenues enough that I think sticking with trains would be where the economy went all on it's own.

So, yeah, I'd say this is the simplest and most realistic way to go about it.

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  • $\begingroup$ Aircraft have for many years had inertial navigation units which allow them to know their position within a mile or so without any external input at all. Not all aircraft have them of course, but they aren't needed as much on Earth. While you do have to give them a position update every so often (perhaps once an hour), an inexpensive radio beacon placed along the intended flight path could provide that update. Visual flight rules are more about keeping inexperienced pilots from crashing into each other or getting disoriented than about navigation. $\endgroup$
    – fluffysheap
    Sep 24, 2017 at 7:16
  • $\begingroup$ @fluffysheap They do have inertial navigation systems, but they are not accurate enough to guide an aircraft all the way to the end of a runway. INS will probably get you within a few miles, but it won't get you down to ILS mins (not every time), which is essentially what you would need if you had variable visibility around a half mile. You may have a point about the radio beacons, I suppose I had figured they had EM interference to a point where it wasn't really reliable at any distance. $\endgroup$
    – Jae Carr
    Sep 25, 2017 at 3:44
  • $\begingroup$ You don't need the INS to guide you to the runway, just to within a mile or two of the airport. Then you can use radio for the actual approach. $\endgroup$
    – fluffysheap
    Sep 25, 2017 at 6:53
  • $\begingroup$ @fluffysheap - I reference this for the third time then: you can't use ILS because radios do not work reliably, and visibility is less than half a mile. Could INS work on occasion? Sure. But I don't think it would work often enough to be considered safe (especially since it can't be calibrated against other systems as it is in real life). Remember, I'm not trying to claim air travel would be impossible, just that it would be sufficiently difficult that the economy would favor trains to a high degree. $\endgroup$
    – Jae Carr
    Sep 25, 2017 at 13:44
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Here are some possibilities:

  1. Perhaps really bad weather. If there aren't any tall mountains (which would get in the way of ground transport) then the winds would whip around the planet faster. This would make for more chaotic weather. Yes, technology could compensate for that but people usually go for the lowest cost solution.
  2. Also, if the communities were all relatively close to each other, it might not be worth the time and fuel needed to lift an aircraft off the ground.
  3. The inhabitants are rich. Rushing is for the poor. Taking their time to get somewhere in style shows/improves their status.
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Generally, modes of transportation are determined by economics first and foremost. If you are transporting thousands of tons of rare mineral elements to the space elevator, shipping it via unit train makes far more sense on a cost basis than any other form of transport. High value items with limited shelf lives need air freight, like 747's flying cut flowers from Columbia to markets in the United States. Just in time manufacturing also needs fast and reliable transport, one of the weirdest examples I ever came across is Mercedes Benz using air freight to ship transmissions to an assembly plant in Tennessee. (note, I may have got the manufacturer wrong, but it is defiantly shipping transmissions from Europe to America).

Now the OP wants high speed surface transportation, so we need to look at the conditions which wold make this more feasible. There are long distances to cover, high gravity and potentially difficult atmospheric conditions. The planet is settled because of mining, and we are also told there is some sort of EM effect which makes long range communications difficult.

So, the priority is carrying large heavy loads of freight, which suggest a railway and unit trains. High speeds might be indicated because the throughput to profitably support an extraterrestrial mine needs to be very high. If weather and EM effects are an issue, then an enclosed line is needed.

Vacuum trains have been proposed for centuries, and a long evacuated tube provides the means for high speed transport to and from the space elevator. As a bonus, people can use the same tubes for high speed rail to and from the mines to the elevator (A large service industry hub would develop there, including all the things miners would like including saloons, entertainment establishments of all kinds, casinos, stores etc.). The EM effects can be bypassed by running conduits along the tubes carrying fibre optic cables, phone lines and even waveguides for radio.

So everything gets wrapped up through the application of economics. The need to deliver large quantities of mineral ore drives everything else. There might be aircraft and other forms of transport, but they will be largely niche elements for special purposes. The only other major form of transportation which might be feasible is rocket powered landers dropping in straight from orbit and returning to space to deliver critical high priority cargo.

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There is something about the makeup of the one of the outer layers of the planet core (or at least something a few miles down) that is providing a dampening effect for the EM radiation, but it doesn't extend that far out from that layer. More than about 1km up from sea level or local equivalent said EM radiation causes sudden and drastic and usually explosively exciting and terminal or near terminal equipment malfunctions, sparking between various bits of metal like a jacobs ladder, etc. Maybe even the actual EM causing issues with earth-norm physiology - sudden muscle spasms, etc. which could include heart, diaphragm, etc.

Sure it could be shielded against just like the landing craft from the exploratory ships, but that would require a size that would require drive technology won't work well near gravitational forces, in an atmosphere (up and down only, no real lateral movement), in that particular atmosphere, logistically effective and supportable, whatever.

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One partial answer not mentioned above is a lack of atmospheric oxygen. If aircraft need to carry oxidizer as well as fuel, flying becomes more inefficient. This would also bias toward high speed rail which I think is what you want, since they would be powered electrically from external sources.

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  • $\begingroup$ I did consider this option, but this doesn't rule out propeller-based air travel, which can still be made very fast. $\endgroup$
    – Brian Lacy
    Sep 21, 2017 at 22:00
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    $\begingroup$ That is why I said it was a partial answer. Combustion fuel still has a higher energy per unit weight then modern batteries (though the gap is closing and might be considered closed in your future timeline). So a battery powered plane would need to deal with less range for the same weight. This combined with limiting factors caused by factors mentioned in other answers might make it impractical. $\endgroup$
    – Lex
    Sep 22, 2017 at 4:53
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People are inventive, someone will find a way to fly in whatever world you might propose that is similar to Earth.

You already mentioned that large corporations seek to exploit the planet for its resources. That means they are not a unified government seeking to populate the planet as an extension of its territory.

Make these corporations competitive, and possibly following a loose code in how to conduct business on underdeveloped worlds. Or they bow to a government which gives them freedom so long as they do not monopolize the planet.

Since communication is difficult on the planet it opens opportunities for people to do things that violate the code. It's also quite possible that these corporations have their own military to protect their assets. Or in some cases to seize illegally obtained assets from their competitors.

Perhaps all flight transportation is easily monitored from space and must be claimed or it will be seized and distributed by the competitors hence the need for discretion when handling more then is allowed by the code.

This also does not rule out smaller competitors who are also allowed to do business on the planet by the same code.

Bottom line, I think people are your best bet for limiting air travel.

I personally liked the predator idea, although not pigeons. Maybe something that's related to the EM emissions and the valuable resource the corporations want. Just like how the worms in Dune were the reason for a whole planet to be a desert yet habitable and have a resource that eventually defines who rules an empire.

Good luck!

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Alternatively, all of your inhabitants could be clautrophobic or otherwise unable to sit comfortably in the relatively cool, dry space of an airline cabin.

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I'll just trow some ideas: If gravity is stronger, that could cause atmosphere to be less thicker, or more charged, and on a bigger planet there are much bigger mountains due the larger movement of larger tectonic plates, so top parts of the mountains usually sticking out from atmosphere, so flying above them requires more expensive technology, than digging a tunnel trough them and vehicles been primary made for transporting big amount of "natural resources", which is easier by ground.

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    $\begingroup$ We have discussed this several times in different questions on the site, but here goes again: Atmospheric pressure and surface gravity are not closely related; other factors dominate. For examples from our own solar system, try Venus (surface atmospheric pressure ~92 atm, gravity 0.904 g), Earth (1 atm, 1.0 g), Mars (0.006 atm, 0.38 g) and Titan (1.45 atm, 0.14 g). $\endgroup$
    – user
    Sep 22, 2017 at 11:52
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The big corporations exploring the rare natural resources of this planet releases the previous inhabitants' malfunctioning and randomly reconfiguring aerial matrices of metal (and flesh) cutting laser beams that are not visible to the naked eye under any lighting. In addition, they awaken and release the remaining indestructible fiercely territorial flying swarms of huge killing creatures with excellent vision and other senses including at top flying speeds and at rest. The sky becomes a war zone of random cutting lasers and the vicious swarms. Even the big corporations' protective aerial high-speed tube system travel (like Elon Musk's concept*) shielding them from terrible weather conditions and their various aircrafts cannot escape destruction from the cutting lasers and swarms. They must travel by ground. Hope this help you.

*See https://www.thestar.com/news/world/2013/08/12/highspeed_tube_travel_concept_unveiled_by_billionaire_entrepreneur_elon_musk.html

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There are all sort potential legal difficulties with air flight on Earth- what happens if a crime happens on a plane owned by Spain, heading from England to distant Russia passing over France. It is only because countries are relatively relaxed about jurisdiction that it is not a big problem. Land Transport is a lot simpler- the country you pass over has jurisdiction. Just make your mega-corporations real awkward about these legal issues on air travel then no one will ever fly the relatively tiny corporations that want to supply air travel will be stiffed.

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Trans-dimensional vortices that open randomly and suck in anything within range; once inside the craft is left do slowly die from entropy, and escape is impossible for a lone craft.

Or if that's too much- then how bout:

Orbital weapons platforms left behind by an ancient alien race; they shoot down anything that gets too high.

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  • $\begingroup$ If either of those are the case, then how did they get to land on the planet in the first place (and every time since)? $\endgroup$
    – Mithrandir24601
    Sep 25, 2017 at 11:01
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Radiation exposure.

The earth is quite well shielded by a magnetosphere, that means we don't get a hard radiation bombardment from the sun.

That's one of the biggest problems with space travel - you need to carry shielding.

So imagine a world where there's no magnetosphere, or the one that there is is much weaker/closer in to the ground. (None at all would mean lots of radiation shielding everywhere, and would make the planet inhospitable to life).

Thus - ground travel is common, because there's more "shelter" from the solar wind, and airborne travel is a radiation hazard - more shielding needed to be 'safe' and thus adding significantly to payloads. Something that's not nearly as much of an issue if you're ground based.

This fits in with your EM emissions too. And for bonus points, gives you a perpetual Aurora.

What would happen if earth lost its magnetic field and could it be caused by humans?

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