Topic: Zeppelin won't fly

[zook2]

"Vehicle can't find a way", but the line is defined and the config says control towers are not required (and are not available in 1909 anyway). What's wrong here?

[jamespetts]

The purple colour says that we are missing control towers; are you sure that the configuration setting was set correctly to allow airports without control towers? Note that airships need no runways: they can take off and land from the gates.

[zook2]

allow_airports_without_control_towers = 1

I didn't change anything there.

[jamespetts]

Did you change it before or after you started your saved game; and did you set this in the main simuconf.tab or the pakset simuconf.tab?

[zook2]

I didn't change it at all. Also I didn't know there is a pakset config.

The default value is 1 in the main config and 0 in the pak128ex config. Apparently the latter takes precedence. Can you tell me why there are two sets of config files and how the two affect each other?

[jamespetts]

The latter does indeed take precedence: the multiplicity of configuration files is common to Standard and Experimental. It exists to allow defaults to be set globally that can be overridden in the pakset configuration. In Pak128.Britain-Ex, you can retrospectively change many aspects of the configuration, including the requirement for control towers, using an in-game GUI accessed by pressing the "i" key. Look for the "Experimental" tab.

[zook2]

Try the following: switch off the "allow_airports..." in the GUI, exit the game and set both config parameters to 1. Restart. You'll get purple lines. Could it be that the parameter isn't read properly?

[jamespetts]

Changing the configuration files will have no effect at all on an existing saved game, as these settings are saved with the game. If you are referring to doing this (and it is not clear), then that is the reason that it is not making a difference.

[Octavius]

There are many small airstrips in the world without a control tower. This is safe, as these small airstrips are only used by small planes (and in good wheather, but this isn't simulated in simutrans) and the pilots can maintain separation by just looking out of the window. Indeed, in the early days of aviation control towers didn't exist. Large airports on the other hand always have a control tower, and flying would be dangerous if they hadn't. This is because large planes fly fast and have a large turn radius, so they can't see each other soon enough and have to rely on air traffic control to maintain separation. Maybe it would be a good compromise to only require control towers for fast planes. Or, maybe easier to implement, assuming nobody is going to build a long runway if the airport is not going to be used by fast planes, require a control tower on airports that have a runway longer than, say, 800 meters.

[jamespetts]

It is actually rather difficult for an airport to detect the length of its own runways in this way. But are there any significant examples of airports with significant quantities of commercial air travel that have nothing that passes for a control tower? I can imagine that there might be small airstrips for leisure flight without them, but I doubt that any commercial airports do not have them.

[Sarlock]

Any airport with any reasonable amount of traffic will have a control tower of some sort.  It's generally just small fields that are primarily for light recreational use that are uncontrolled -- usually communication occurs between planes in the area that are using the airspace rather than through a control tower.

[Octavius]

It is actually rather difficult for an airport to detect the length of its own runways in this way. But are there any significant examples of airports with significant quantities of commercial air travel that have nothing that passes for a control tower? I can imagine that there might be small airstrips for leisure flight without them, but I doubt that any commercial airports do not have them.

Not any more (except from some very remote locations that cannot be reached in any other way, maybe for workers in remote mines), but I think they existed in the 1920s or so, the zeppelin age. Not much point in making an airport available when control towers don't exist yet. Right now you can set in your configuration whether you want to be realistically forced to use control towers on modern airports and at the same time ignore the early years of aviation, or completely ignore control towers. Point is, control towers indeed didn't exist in 1909. Would it be possible to require control towers when available? Like in, government says "Now that this new technology is available, let's make it obligatory for public safety"? Although one would need a short transition period.

[jamespetts]

Not any more (except from some very remote locations that cannot be reached in any other way, maybe for workers in remote mines), but I think they existed in the 1920s or so, the zeppelin age.

Is there an historical source for this? One might imagine something vaguely akin to a control tower albeit some way from what we would understand by one to-day.

[Isaac Eiland-Hall]

I did watch a documentary a few days ago about passenger/freight air service in Colombia to remote villages where air was the only way in or out. There were several such villages mentioned in the jungle; in each case, it was a dirt strip with no control.

But this is pretty rare, and the question becomes how much reality vs. simplicity in the simulation.

[Spacethingy]

Perhaps Zeppelin-era control towers could be painted to look like docking towers? That way you satisfy the both the control tower mechanism and the simplicity requirement.

[jamespetts]

Perhaps Zeppelin-era control towers could be painted to look like docking towers? That way you satisfy the both the control tower mechanism and the simplicity requirement.

That's an interesting thought. Would anyone like to produce the graphics for this...?

[Ves]

Cant the lack of a control tower set a delay in runway reservations? An airport without a control tower forces the airplanes to reserve the runway earlier/longer time than if the airport has a control tower. Reflects that in real world, operating (unrealistically today, but more present in earlier days I think) without a control tower would force the planes to operate with bigger margins. Even different levels of towers could be introduced simulating how the technique has evolved to cope with more traffic

[jamespetts]

Is there an historical source for this that would give enough information to calibrate the level of delay reasonably accurately? Also, this would be a lot of work to code for a rather marginal case of very early airports.

(However, on the subject of airports, I am in the process of adding more runway types. The current pakset has grass and asphalt - I have added concrete, but my research has not given me useful information as to the prevalence of other runway types such as gravel, and I should be grateful in particular if anyone knows of any reasonably commonly used runway types in commercial airports that are intermediate between grass and asphalt - i.e., allow aircraft the size of small jets to land but are only durable enough to be a useful surface treatment for a lightly used airport; is a tar MacAdam surface actually common in airport runways?)

[Ves]

I don't know whether there are any historical info that aims for this. Closest would be to ask a person with a pilots license and ask her or him how the procedure would be an evt how the timeline for the procedure would look like. 

[Sarlock]

Landing at Uncontrolled Airports

Given that we are dealing with commercial aircraft, not light private aircraft, we can probably safely assume that our airports are always a controlled airspace.  Uncontrolled aerodromes are common in small rural areas but these do not accept larger commercial aircraft.

Types of runways

You're not going to see the aggregate types very often anymore - and for commercial applications never really saw them much to start with.  Aggregate (gravel, etc) can be sucked in to engines/damage propellers, so they are generally not used except at smaller rural sites or northern areas that cannot easily maintain asphalt/concrete.

For Simutrans purposes it probably doesn't warrant worrying about anything beyond grass and asphalt/concrete.

[jamespetts]

Thank you very much. I added tar MacAdam, too, as an intermediate between grass and asphalt, as there was a big gap between them. That allows me greatly to reduce the weight limit of the grass to make earlier aircraft such as the DC-3 more useful on such airfields in later years.