Questions regarding Taxi and Pushback

[Gerrit Addiks]

Hello fellow Pilots,

First a disclaimer: I am unsure if this sub-forum is even the correct place to ask this question. Am I correct in interpreting "Pilot Talk" as in "Place for Pilots to talk about aviation" and the other sub-forum "Controller Talk" as "Place for Controllers to talk about aviation"? Or is it the other way around: Is "Controller Talk" meant as "Everyone talking about Controlling topics" and "Pilot Talk" meant as "Everyone talking about Piloting topics"? Who talks in what sub-forum about what? It *seems* like there are mostly controllers talking in "Controller Talk", but that might be a wrong impression.

Now to the actual questions, starting with the situation:

A few days ago I was trying to take off from Stuttgart (EDDS), Parking stand 72, facing north. The opposite Parking stand 62 was empty. Active runway was 07.
When I look at the chart with the parking stands, there are two ways I could have taxied to the holding point, either forward over stand 62 and taxiway M, or backward directly onto taxiway N.
The backward way via N would need a pushback, the forward way via M would not need a pushback.
In order to figure out if I needed to prepare (pre-plan) a pushback, I asked the controller "[CALLSIGN], Please advice taxi route, will I taxi via Mike or November?" and the controller responded by directly giving me a taxi clearance via Mike (over empty Stand 62). I was not ready to start taxiying immediately, but I sort of rushed my checklist and started taxi via Mike ASAP.

Is there a way for me to ask the controller which route he will give me without getting a taxi clearance directly?
How much time do I actually have to start taxying? I was under the impression that I was expected to start taxying directly.
What happens if I realize that I will need pushback for the given taxi-route after already having the taxi clearance?
Can I expect that the controller will always give me a taxi route that I am actually able to start following immediately?
What would have happened if there was another aircraft on 62, blocking my way to taxiway Mike? There is a diagonal bar on the chart to stand 71/61, but if I remember correctly there was a light-pole in the way between the stands. (I may misremember the actual number of the stand) Would I have been asked to taxi via November? Would the controller have realized that I would need a pushback that way?

Directly after this situation I was faced with the next challenge: My simulator is X-Plane 11 and I was flying with reduced graphical effects (no HDR) at night, meaning that the taxi-ways were not actually illuminated in the simulator and I had a hard time with A) determining if stand 62 actually was empty or not and B) Making out if I was on the correct taxi-way or if I had taxied the wrong way. I was still somewhere on my way on taxiway Hotel (a long way before the holding point) when the Ground-Controller was telling me out of the blue to contact tower. I told him that I was still taxying and that I was not sure where I was.

Is it normal that ground is already handing me over to the tower long before the holding point?
Could I have turned off real-time weather and time to get some daylight? Or is real-time mandatory on VATSIM? Would it be disrupting if people fly with different wind- or light-settings?

I have since increased my graphic settings in X-Plane (enabled HDR) in order to get some light on the taxi-way. I just hope that this does not reduce my FPS so much that I will get kicked from the network again. I have previously lowered my settings exactly because I was kicked for low FPS beforehand. Sorry, I only got a GTX 1650.

[Andreas Fuchs]

Hi Gerrit and welcome to the gang!

Don't worry too much about what you would post where. "Pilot talk" is absolutely fine for this topic.

13 minutes ago, Gerrit Addiks said:

I sort of rushed my checklist and started taxi via Mike ASAP

Yeah, no need to do this. The ATCO obviously misunderstood your question and you simply should have advised him that you were only requesting information and that you are not ready to taxi yet. No problem at all. A better way to ask would have been "[ATC-Callsign][CALLSIGN], confirm you want us to pushback from stand 72 or can we expect self-maneuvering?" (or something similar). Again: in principle you asked a question and the ATCO misunderstood it as "ready for taxi".

16 minutes ago, Gerrit Addiks said:

Is it normal that ground is already handing me over to the tower long before the holding point?

Yes, depending on the airport layout. In Stuttgart there is nowhere "wrong" that you can go, once you are on taxiway N and past all intersecting taxiways where conflicting traffic could affect your movement. You do not need to call Tower immediately. It is sufficient to contact them only when you are near or at the holding point and when you are ready for departure.

Regarding your issue with not clearly seeing the taxiways, yes, you could have set daylight temporarily. In X-Plane 11 you change the SIM-time with the keys "K" and "L". If you hold down "SHIFT" before and while you press "K" or "L", the time-steps will be bigger and thus the change from night to day quicker.

You can use whatever time/light-conditions in your SIM, it is 100% your choice. The only thing that you HAVE TO have according to realworld conditions is weather data: pressure (QNH), winds and temperature.

I have a GTX1060 and I do not experience any major issues with frames dropping below 20. I suggest you play with the "Number of World Objects" in X-Plane's graphics settings. Shadows and reflections also have a big impact on the speed of your SIM. I rather keep "Visual Effects" in "High (HDR)", if possible.

[Daniel Mckee]

I am not that familiar with EDDS but using X-Plane 11 the aircraft is pointing north(ish) nose first into Stand 72. Surely one would always push back on to November and rarely if ever go across an empty  stand 62 to Mike ???

[Lauri Uusitalo]

On 10/18/2022 at 2:19 PM, Andreas Fuchs said:

I have a GTX1060 and I do not experience any major issues with frames dropping below 20. I suggest you play with the "Number of World Objects" in X-Plane's graphics settings. Shadows and reflections also have a big impact on the speed of your SIM. I rather keep "Visual Effects" in "High (HDR)", if possible.

I think HDR setting does not have any effect on framerates, but I could be of course wrong. But without HDR XP11 is unusable to me at least.

[Andreas Fuchs]

12 hours ago, Lauri Uusitalo said:

I think HDR setting does not have any effect on framerates, but I could be of course wrong. But without HDR XP11 is unusable to me at least.

That is possible, I only shared my general graphics settings that provide me with good frames in Vulcan mode. I am not an expert.

[Andreas Fuchs]

18 hours ago, Daniel Mckee said:

I am not that familiar with EDDS but using X-Plane 11 the aircraft is pointing north(ish) nose first into Stand 72. Surely one would always push back on to November and rarely if ever go across an empty  stand 62 to Mike ???

If ATC instructs you to taxi this way, why not? There are stands that are only defined by ground markings and nothing will obstruct your movement. It differs from airport to airport.

[Tobias Dammers]

On 10/18/2022 at 12:55 PM, Gerrit Addiks said:

Is there a way for me to ask the controller which route he will give me without getting a taxi clearance directly?

You pretty much did it correctly - it's the controller who mistook your request as a taxi clearance request rather than a purely advisory one. But, as Andreas has pointed out, you are not required to accept the taxi clearance and start taxiing ASAP; just call them back and say that you didn't mean to request taxi just yet, and it'll be fine.

On 10/18/2022 at 12:55 PM, Gerrit Addiks said:

How much time do I actually have to start taxying? I was under the impression that I was expected to start taxying directly.

It is expected that when you request a taxi clearance, you are ready to start moving immediately. If for whatever reasons you can't, it's best to call them back and inform them - however, they are also watching you (on their ground radar scope, or through the simulated control tower windows), and if a conflict is about to arise because you started moving too late, it is their responsibility to intervene (usually by calling you or the other aircraft and telling you to hold position / give way).

On 10/18/2022 at 12:55 PM, Gerrit Addiks said:

What happens if I realize that I will need pushback for the given taxi-route after already having the taxi clearance?

You call them up and say something like "unable taxi-out onto N from stand 72, request pushback", or, if you suspect that they actually meant to get you onto M, you could first say "confirm taxi via M", and they will either say "affirm" and you can then request pushback, or they realize their mistake and give you the corrected taxi clearance. And if in doubt, you can always revert to plain English.

On 10/18/2022 at 12:55 PM, Gerrit Addiks said:

Can I expect that the controller will always give me a taxi route that I am actually able to start following immediately?

In principle, yes - once you get your taxi clearance, you are allowed to start moving according to it immediately. However, while they should have a good enough idea of what various aircraft types can and cannot do, the responsibility for this is ultimately with you, the PIC, and if they give you a clearance that you cannot safely follow, then you need to reject it and tell them why. (This goes for all clearances, not just taxi clearances).

On 10/18/2022 at 12:55 PM, Gerrit Addiks said:

What would have happened if there was another aircraft on 62, blocking my way to taxiway Mike? There is a diagonal bar on the chart to stand 71/61, but if I remember correctly there was a light-pole in the way between the stands. (I may misremember the actual number of the stand) Would I have been asked to taxi via November? Would the controller have realized that I would need a pushback that way?

Again, as PIC, you are ultimately responsible for the safety of your flight, so if you're cleared for something you can't do, tell ATC "unable due (reason)", and they will have to figure something out. People make mistakes, this is part of why there are pilots in the cockpit and human controllers in the tower - everyone involved is expected to "apply brain" and speak up when anything looks fishy.

[Andreas Fuchs]

Has Gerrit ever read and acknowledged our replies? 😞

[Gerrit Addiks]

Oh, yes. Sorry for not replying. I have read them all and thank you for the answers.
I just did not feel like I could contribute much more to this topic, so I had nothing more to add.

[Andreas Fuchs]

That's why we have those lovely emoticons at the right bottom corner of each reply. They may give those who cared to reply, a sense of acknowledgement that you have read and understood the information. 😇

[Magnus Meese]

On 10/18/2022 at 12:19 PM, Andreas Fuchs said:

Yes, depending on the airport layout. In Stuttgart there is nowhere "wrong" that you can go, once you are on taxiway N and past all intersecting taxiways where conflicting traffic could affect your movement. You do not need to call Tower immediately. It is sufficient to contact them only when you are near or at the holding point and when you are ready for departure.

This is increasingly common, however I personally find it annoying to not be called when I know ground said "contact", which is an instruction. Almost every workday now I see someone miss an arrival gap or crossing gap just because they didn't call sooner, but from how they then call me it is clear they would have been ready and able. Does it matter in the long run if we're not operating at max capacity? Not really. Does it give me gray hairs? A couple.

[Andreas Fuchs]

Really? It is the pilot's loss if he missed a gap. Nothing that really affects ATC.

[Dustin Rider]

2 hours ago, Andreas Fuchs said:

Really? It is the pilot's loss if he missed a gap. Nothing that really affects ATC.

True, unless the pilot happens to be at the front of a growing line of traffic waiting to cross a runway or holding up a growing line of departures. The flow of the operation gets interrupted and it can knock someone off their stride.

[Andreas Fuchs]

1 hour ago, Dustin Rider said:

True, unless the pilot happens to be at the front of a growing line of traffic waiting to cross a runway or holding up a growing line of departures. The flow of the operation gets interrupted and it can knock someone off their stride.

I knew that this reasoning would come up 🙂 Usually and in many places you have intersections and you can continue using a runway, even if the holding point at full length is occupied.

[Dustin Rider]

Of course! But it does add to the workload of the controllers. What if the aircraft is blocking the most efficient way across a runway? Assigning a departure to an intersection departure now means I may have to advise them how much runway is remaining, solicit the pilot's approval to use that intersection, and wait until they run the new performance numbers (as all VATSIM pilots do, no doubt 😉). Okay, I know I'm going off the deep end here, and the point Magnus makes means a momentary delay in operation, but I had to chime in and say that there is certainly *some* adverse impact to ATC.

From my perspective on the "light" side of the microphone, I've noticed many major US airports prefer pilots monitor the tower frequency as opposed to contact them. On one hand there is less frequency congestion but on the other it doesn't give the controller a heads up as to how quickly a crossing can be accomplished, as Magnus puts it. Where I have really seen the dichotomy of "monitor" versus "contact" play out is at a pair of Class D airports in Colorado: APA and BJC. The former insists all taxiing departure traffic remain on ground control frequency until told to monitor the tower. This results in positive control over the sequence at the end of the runway and helps reduce the workload of the local controller. At the latter airport, there is no point at which ground makes the handoff to tower and only a handful of aircraft actually call the tower when they're ready meaning that the local controller is constantly asking who is next in line at the departure end of the runway in addition to managing all airborne traffic. I got a little carried away, here, but I've always enjoyed geeking out about how, and, more importantly, why operations are conducted the way they are.

[Andreas Fuchs]

Hi Dustin,

in our scenario we talked explicitly about pilots taxiing towards their runway holding points from where they are going to depart. Don't make it overly complicated. If crossing a runway was involved in that scenario, pilots definitely would have to call within a timely manner. Traffic crossing runways does not affect traffic on their way to holding points in most places that I visit. These are special cases. We are trying to keep it general here.

Also, the scenario where TWR does not know who is whom at a holding point is mostly a thing of the past. With the ground radar display that ATC has these days, they can clearly identify all aircraft.

On top of it, the reasoning being performance calculations, does not count in the real world: us professional crew always have intersection data ready for such scenarios. It's part of the departure briefing, we know what we can accept. On VATSIM it does not really make a difference, since 90% of pilots here do not have a clue about takeoff performance calculations.

Conclusion: in the real world we will usually call TWR only when we are ready for departure. Otherwise it will result in even more talking, because in a lot of cases ATC does not listen actively what is being said and calling in right away "will report ready" often results in "runway xx, cleared for takeoff". This in turn makes us call them again to advise that we are not yet ready, resulting in even more talking. What a colossal waste of effort and time. We are busy on the flight deck, running our checklists and briefings. Been there, done that and I hate this inefficiency.

[Magnus Meese]

8 hours ago, Andreas Fuchs said:

Really? It is the pilot's loss if he missed a gap. Nothing that really affects ATC.

We joke that pilots only think about themselves and not the big picture traffic wise. Turns out it's not a joke, fancy that 😉

1 hour ago, Andreas Fuchs said:

If crossing a runway was involved in that scenario, pilots definitely would have to call within a timely manner

Plenty do not.

1 hour ago, Andreas Fuchs said:

With the ground radar display that ATC has these days, they can clearly identify all aircraft.

Some airports, sure. Mine? No. However, we have strips and we know who is who. Knowing who you're talking to is ATC ABC.

1 hour ago, Andreas Fuchs said:

us professional crew always have intersection data ready for such scenarios. It's part of the departure briefing, we know what we can accept.

Plenty do not.

1 hour ago, Andreas Fuchs said:

Conclusion: in the real world we will usually call TWR only when we are ready for departure. Otherwise it will result in even more talking, because in a lot of cases ATC does not listen actively what is being said and calling in right away "will report ready" often results in "runway xx, cleared for takeoff". This in turn makes us call them again to advise that we are not yet ready, resulting in even more talking. What a colossal waste of effort and time. We are busy on the flight deck, running our checklists and briefings. Been there, done that and I hate this inefficiency.

Try "not ready", might help. I desperately want everyone to call me ready / not ready right away. I pick my departure order based on minimum total delay, and I need some info to do it. Also the amount of big name airline crews who taxies to the end and dont' say anything before the ready-to-go airliner behind them has passed all preceding intersections and is now stuck, is maddening. Yes, I will chase you guys up and wrestle from you the information I need, but sometimes other tasks prevents that from being done.

You will find tons of controllers on both sides of the fence, as well as pilots obviously, such is life. I personally just wish more pilots actually treated "contact" as the instruction it is. I'm going to stop ranting now, before someone gets me going on pilots who reads back "monitor" and instantly starts speaking on the new frequency! 😄

Edited November 2, 2022 at 09:44 PM by Magnus Meese

[Andreas Fuchs]

Come and control somewhere in Southern Europe and then you won't care anymore 😄

[Dustin Rider]

21 hours ago, Andreas Fuchs said:

in our scenario we talked explicitly about pilots taxiing towards their runway holding points from where they are going to depart.

Indeed and thank you for clarifying.

21 hours ago, Andreas Fuchs said:

Also, the scenario where TWR does not know who is whom at a holding point is mostly a thing of the past. With the ground radar display that ATC has these days, they can clearly identify all aircraft.

This is more true at the places I visit under Part 121. Nearly all the places I visited under 135 have no ground radar and rely on pilot reports, strips, and looking out the window. On VATSIM, of course, all controllers have ground radar of some kind.

21 hours ago, Andreas Fuchs said:

Conclusion: in the real world we will usually call TWR only when we are ready for departure. Otherwise it will result in even more talking, because in a lot of cases ATC does not listen actively what is being said and calling in right away "will report ready" often results in "runway xx, cleared for takeoff". This in turn makes us call them again to advise that we are not yet ready, resulting in even more talking. What a colossal waste of effort and time. We are busy on the flight deck, running our checklists and briefings. Been there, done that and I hate this inefficiency.

I successfully prevented an unnecessary takeoff clearance by giving the tower a heads up that we needed another minute at the end of the runway. It was simply a matter of reading the frequency and working with an attentive local controller. It seems we've moved onto a discussion on human factors for which there is no simple answer and everyone's results may vary. I have enjoyed this discussion, though.

[Andreas Fuchs]

50 minutes ago, Dustin Rider said:

This is more true at the places I visit under Part 121. Nearly all the places I visited under 135 have no ground radar and rely on pilot reports, strips, and looking out the window. On VATSIM, of course, all controllers have ground radar of some kind.

Yeah, I am operating mostly in Europe and you are either at huge and busy airports that have all those technical helpers available, or small airports where ATC won't have any issues identifying us without a doubt.