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Meyerflyer

Taxi speed limited to 32kt?

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Hi,

 

a strange thing I'm seeing for a long long time. Whenever I taxi on a taxiway and accelerate the engines, the Bus starts accelerating too. It speeds up smooth and constantly but suddenly stops getting faster after reaching 32kt. Is this intended? If yes, why?

 

When ATC tells me "high speed taxi approved", I cannot get any faster than 32kt even though I want to. Maybe only if I set way more thrust than normally would be needed to accelerate beyond 32kt. It feels like there is some programmed target taxi speed of 32kt, but why? Does anyone else have this issue?

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What is a "normal" taxi speed for you?

 

In least in my airline anything beyond 30 is prohibited unless backtracking an active runway where you can go up to 50kt.

Anything beyond about 34kt would even trigger an alert sent to the airline for which you can get into serious trouble.

There is no thing like "high speed taxi approved" in real life, that's a VATSIM thingy. For sure it doesn't exist in Europe in real life. You can always go up to 30kt unless there is a legal limit specified on the charts.

ATC may ask you to expedite taxi but even then, in my airline it's not more than 30kt.

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Okay, it's one thing, that it is obviously not allowed to taxi faster than 30kt (which I didn't know until now). But why does the Aerosoft Airbus stop accelerating? I'm sure the real Bus does not brake automatically to stay below 30kt. :D

 

Btw. I know that you normally do not taxi essentially faster than 30kt. But I would expect to be able to taxi faster if I want to.

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6 minutes ago, Meyerflyer said:

Okay, it's one thing, that it is obviously not allowed to taxi faster than 30kt (which I didn't know until now). But why does the Aerosoft Airbus stop accelerating? I'm sure the real Bus does not brake automatically to stay below 30kt. :D

 

Btw. I know that you normally do not taxi essentially faster than 30kt. But I would expect to be able to taxi faster if I want to. 

 

With sufficient thrust you surely can taxi faster. 40% or higher can be quite normal to accelerate to these speeds.

How much thrust do you usually use for taxi?

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Normally not more than 30% N1. I would understand when the acceleration during taxi would get slower and more thrust would be needed to get higher taxi speeds. The thing I disagree is, that the acceleration suddenly stops when reaching 32kt.

 

That seems to be at least a bad line in the code of the Bus. Or does your RL plane stop accelerating when reaching 30kt? :)

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42 minutes ago, Meyerflyer said:

Normally not more than 30% N1. I would understand when the acceleration during taxi would get slower and more thrust would be needed to get higher taxi speeds. The thing I disagree is, that the acceleration suddenly stops when reaching 32kt.

 

Does it work at 40%? With 30% it might not work in the real aircraft either. At least in mine (different aircraft, same engines) 30% would by far not be enough to accelerate beyond 30kt unless you got time to spare... loads of time!
How "suddenly" does it stop? Could you send us a small video to show exactly what  you mean?

Do you notice any abrupt change on the speed trend vector during acceleration for takeoff? This could be an indication there is something generally wrong here.

 

42 minutes ago, Meyerflyer said:

hat seems to be at least a bad line in the code of the Bus. Or does your RL plane stop accelerating when reaching 30kt? :)

 

Believe me, it does. Because we make it stop ;)

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Thank you Emanuel. I will try recording it on my next flight. But that will probably take some time as I'm going to fly to Mallorca next week. (Probably with the aircraft type you're flying in real life ;) )

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I thought there is 20kt limit for taxi on taxiways in all airports unless your plane is military or you are taxiing on runway and Vatsim DOES observe 20kt speed limit for all airports.  Since when they increase to 30kt limit?

 

Regards,

 

Aharon

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40 minutes ago, Aharon said:

I thought there is 20kt limit for taxi on taxiways in all airports unless your plane is military or you are taxiing on runway and Vatsim DOES observe 20kt speed limit for all airports.  Since when they increase to 30kt limit?

 

That's definitely a VATSIM myth.

 

There is no 20kt limit in real life.

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I think 25-30kt is a "normal" taxi speed that most of the airlines use on a straight and obstacle free taxiway.

 

Except for some turkish pilots. I have been in the tower of a bigger german airport 3 or 4 times and I've seen some turkish airlines taxiing at about 5kt. I was confused and asked my air traffic controller friend and he said that these pilots only get paid for flight time. And the taxi time counts as flight time.

 

So what do they do? They take as long as possible to get to the gate after landing to earn more money. ATC even has to reroute other landed traffic behind them to the parallel taxiway in this case so they could take over the turkish planes. Crazy thing and I've seen it many times. :D

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1 hour ago, Meyerflyer said:

I think 25-30kt is a "normal" taxi speed that most of the airlines use on a straight and obstacle free taxiway.

 

Except for some turkish pilots. I have been in the tower of a bigger german airport 3 or 4 times and I've seen some turkish airlines taxiing at about 5kt. I was confused and asked my air traffic controller friend and he said that these pilots only get paid for flight time. And the taxi time counts as flight time.

 

So what do they do? They take as long as possible to get to the gate after landing to earn more money. ATC even has to reroute other landed traffic behind them to the parallel taxiway in this case so they could take over the turkish planes. Crazy thing and I've seen it many times. :D

 

So that's why the Turkish are always taxiing that slow... at once when I had a Turkish in front of myself the captain and me were already wondering and making jokes that we wouldn't even know how to taxi that slowly, even if we wanted... they must have mastered the thrust settings needed for those 90° turns into the gate at 1-2kt ;)

 

This is actually part of the reason why my company pays per scheduled block hour and not per actual.

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Thanks to all for kind answers and for letting me know that 20kt limit for taxi speed is biggest myth

 

Regards,

 

Aharon

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@Emanuel Hagen I recorded a video with Nvidia Shadowplay a few days ago but I was unable to upload it to Youtube without having the quality fully degraded after upload.

 

I was on the taxiway L in EDDF with the A321 IAE and set thrust to about 25-30% N1. The Bus accelerated smoothly by let's say 1kt every 2-3 seconds and stopped immediately at 32kt.

 

I then set N1 to 50% N1 for about 3-4 seconds but the speed never got beyond 32kt.

 

It must be absolutely easy to reproduce for you or one of the AS guys. Could you please check that yourself?

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Ground friction in the sim is properly porked and we will not spend time on this issue at this moment, sorry.

 

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I tested it today. Taxi with more than 32kt is possible. I had set 50%N1.

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Ok. Imho this is not realistically simulated if the accerleration stops at a certain point and can only be overwritten with an unusual amount of thrust. But thanks for testing.

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As said: Ground friction in the sim is properly porked and we will not spend time on this issue at this moment, sorry.

 

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Because we believe this topic has been answered we have closed it. If you have any more questions feel free to open a new topic.

 

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