Inebriated ATC or Design Flaw?

[jvile]

BK

You are probably correct in your logic thinking since one was going to the Gate. In some cases you have to look further down the line and see what ATC is doing that caused one to hold (arrival) at that point on the taxiway.

It may have nothing to do with the plane taxing to the hold short in the opposite direction but then again it could be that ATC wants your arrival over on the parallel taxiway the outbound is using.

Only when the outbound arrived at the holdshort did ATC release the arrival for a continuation toward parking. It is the blind leading the blind and ATC does not always know the position of each planes movement until it crosses a node or changes to a different taxiway designator.

This type technology goes back to the days of real world ATC where they did not always know where a plane was until the plane reports its position from a manual mike (voice). Thats when ATC would update the shrimp boat strip. ATC movement on ground in FSX is a true closed loop and updates the loop based on the plane passing over something (node) or onto something (new taxiway link) or up to something (a hold short node)

Because your taxiway is not a segmented taxiway (I am assuming) then ATC can't release the arrival for further movement until the departure plane is at a place ATC knows where it is.


KMIA

I set the L taxiway so when AI Planes land on 8L the diamonds across 8R do not penalize and hold up the arrival plane.

Plane lands on 8L/26R and gets it parking spot assigned. At that point the plane thinks the taxiway is a clear taxiway all the way to the GATE at least when crossing the runways so I don't see a hold put on them over there. The hold is normally put on them once they cross over 8R/26L which is the departure runway. Some AI have to hold until a taxiway or Gtae parking is cleard out before they continue.

 

[rfields]

When you are tracking AI aircraft - always have the TrafficToolBox Explorer and Map available.

They give you a lot of information about the specific aircraft being tracked and what FS plans for the next step(s).

 

[Bob Keeshan]

Because your taxiway is not a segmented taxiway (I am assuming) then ATC can't release the arrival for further movement until the departure plane is at a place ATC knows where it is.

Jim,

If I understand you correctly, I should add additional nodes to the parallel taxiway so ATC will know where aircraft are on the taxiway and not issue hold short instructions? I'll give it a try tonight and see how it goes.

Thanks.

BK

 

[Lupo]

segmentation

Hi Bob

What I believe Jim is referring to is a method to further divide a longer taxi run so that there is a separation of tasks if you have an aircraft at both ends of the run. What you do is make several taxi names of say "A" and then group sections of the taxiway into each index. So in effect you have three or four sections within the total run, each with multiple segments. This way FS has more flexibility in moving the traffic. Though as Reggie alludes to earlier in this post I'm not certain that our segmentation behaves like FS native runs.

Hope this helps

 

[jvile]

What I believe Jim is referring to is a method to further divide a longer taxi run so that there is a separation of tasks if you have an aircraft at both ends of the run.

Thanks Lupo

That is what I am refering to.

We feel for the most part that segmented still work but no Utility could ever do it. All my segmented in the past was coded by hand in XML.

The PRO Version should have segemented features which will probably confuse a lot that never realized what the did.

Good to hear from you

 

[Bob Keeshan]

Thanks Lupo

That is what I am refering to.

We feel for the most part that segmented still work but no Utility could ever do it. All my segmented in the past was coded by hand in XML.

Jim,

Do you have an example of how you did this? Did you use it on KMIA?

 

[jvile]

Open a stock KJFK airport with ADE

Top menu select List/taxi designators

Left click on the Name in the list so all taxiway letters sort by alpha

Move the large window out of the way and hightlight each letter "A"

Segmented allows one AI plane to continue on a taxiway on the other side of JFK when another AI Plane is taxing a mile away. ATC will not see the 2 planes on the same taxiway like small airports do.

Ray says segmentation can be added to ADE taxiways (duplicate) and Jon confirms he coded it so you can add as many duplicate letters as needed.

I did not know this feature was enabled and doing studies to be sure it is working correctly.

 

[DougMatthews]

For KLAS - one of the INTENSELY frustrating things the Aces team does for some airports is put a special fix code for that airport only into some of the .DLL files.

Rather than fix the system, they make a one-off exception.

Can you please provide an example of one of these one-off exceptions we have baked into the .DLL files? All the scenery passes through my tools and I was not aware that we did this.

-Doug

 

[rfields]

I'll have to retract that as far as KLAS Doug..

However the two localizers assigned to one runway at KSNA in FS2004/ FSX and KASE in FSX - that's coding we haven't been able to make work with SDK standards/ BGLComp.

What I've tested and found is that our four year old understanding of hold short nodes and the distance they need to be from the runway work is wrong.

The distance from the runway varies with aircraft size (I still don't know if it is model radius or wing_span= value in FSX).

 

[DougMatthews]

I'll have to retract that as far as KLAS Doug..

However the two localizers assigned to one runway at KSNA in FS2004/ FSX and KASE in FSX - that's coding we haven't been able to make work with SDK standards/ BGLComp.

I had a look at our XML source for KASE in FSX. The runway 15 element contained two ILS elements, one right after the other. Nothing fancy. Try that and if it does not work start another forum thread and post your XML that does not work.

What I've tested and found is that our four year old understanding of hold short nodes and the distance they need to be from the runway work is wrong.

The distance from the runway varies with aircraft size (I still don't know if it is model radius or wing_span= value in FSX).

What we typically do for taxiways that are not straight off the end of the runway:

distHSFromRwyCenterJunction = ((0.5 * RwyWidth) + TaxiWidth) / sin(meetAngle);

(meetAngle for a 90 degree junction would be 90)

This has nothing to do with aircraft radii or wingspans.

-Doug

 

[jvile]

I had a look at our XML source for KASE in FSX. The runway 15 element contained two ILS elements, one right after the other. Nothing fancy. Try that and if it does not work start another forum thread and post your XML that does not work.

Doug

The ADE Pro Edition Utility handles double Localizers added to the runway end without any problems. I don't think we will need a post on that issue.

 

[rfields]

Doug,

I wasn't clear enough.

We've been under the impression since Sept 2003 that a hold short node has to be within about 225 ft of the runway. Otherwise AI and user aircraft will not be able to contact the tower and ask for takeoff clearance.

We've seen many instances - like RODN Rwyu 9L and Rwy 9R in FS2004 where the hold shot node is less than 225 ft from the blastpad/ overrun - but more than 225 feet from the actual runway.

AI aircraft in FS2004 would not takeoff on these runways at this airport unless the nodes were moved to within about 225 ft of the actual runway. This also occured with user aircraft.

By that "rule", both AI and user aircraft should not be able to takeoff from Rwy 19R at KLAS. When they taxi to the hold short node on Taxiway J - that node is about 162 feet from the runway Taxipath / centerline on the blast pad. That node is about 375 feet from the edge of the runway.

When observing AI traffic, aircraft 15M and larger half wing span value will ask for takeoff clearance from that point. AI aircraft smaller than 15M will sit at the node and time out without asking for takeoff clearance.

With user aircraft - those under 13M in half wing span value do not get the option to request takeoff at the HS node. Some aircraft between 13M and 17M get the option at the HS node, some do not.

Testing a variety of default aircraft - the C-172 has to taxi onto the runway blast pad for about 100 feet from the junction before it has the option to request takeoff.

The default DC-3 - 16M - has to taxi just past the HS node.
The default CRJ - 13M - can request takeoff at the HS node.
The default B744 - 33M - can request takeoff almost 550 ft away from the runway, back on the west side of where Taxiway J changes to Taxiway H as it crosses Taxiway F.

All user aircraft test were done from parking spot N Parking 44 with the spot turned to heading 116.3 so it was a straight taxi out for user aircraft.

How close the HS node has to be to the runway part of a runway with a blast pad/ overrun is a very important item for people interested in AI. There are dozens of airports where the last taxiway joins on the blast pad / overrun.

There are also many situations like the default PADQ where takeoffs are often directed from Rwy 25 - however the default taxi route is "Taxiway F, Runway 7, Taxiway D, Taxiway C, Runway 36, Runway 7"

User aircraft never get the option to ask for takeoff clearance.

AI aircraft stop at the last hold short where C and B meet near the Rwy 18/36 & 11/29 junction.

We have to place a HS node on Rwy 18/36 near it's junction with 7/25 - how close?

 

[DougMatthews]

Doug,

I wasn't clear enough.

We've been under the impression since Sept 2003 that a hold short node has to be within about 225 ft of the runway. Otherwise AI and user aircraft will not be able to contact the tower and ask for takeoff clearance.

We've seen many instances - like RODN Rwyu 9L and Rwy 9R in FS2004 where the hold shot node is less than 225 ft from the blastpad/ overrun - but more than 225 feet from the actual runway.

AI aircraft in FS2004 would not takeoff on these runways at this airport unless the nodes were moved to within about 225 ft of the actual runway. This also occured with user aircraft.

By that "rule", both AI and user aircraft should not be able to takeoff from Rwy 19R at KLAS. When they taxi to the hold short node on Taxiway J - that node is about 162 feet from the runway Taxipath / centerline on the blast pad. That node is about 375 feet from the edge of the runway.

When observing AI traffic, aircraft 15M and larger half wing span value will ask for takeoff clearance from that point. AI aircraft smaller than 15M will sit at the node and time out without asking for takeoff clearance.

With user aircraft - those under 13M in half wing span value do not get the option to request takeoff at the HS node. Some aircraft between 13M and 17M get the option at the HS node, some do not.

Testing a variety of default aircraft - the C-172 has to taxi onto the runway blast pad for about 100 feet from the junction before it has the option to request takeoff.

The default DC-3 - 16M - has to taxi just past the HS node.
The default CRJ - 13M - can request takeoff at the HS node.
The default B744 - 33M - can request takeoff almost 550 ft away from the runway, back on the west side of where Taxiway J changes to Taxiway H as it crosses Taxiway F.

All user aircraft test were done from parking spot N Parking 44 with the spot turned to heading 116.3 so it was a straight taxi out for user aircraft.

How close the HS node has to be to the runway part of a runway with a blast pad/ overrun is a very important item for people interested in AI. There are dozens of airports where the last taxiway joins on the blast pad / overrun.

There are also many situations like the default PADQ where takeoffs are often directed from Rwy 25 - however the default taxi route is "Taxiway F, Runway 7, Taxiway D, Taxiway C, Runway 36, Runway 7"

User aircraft never get the option to ask for takeoff clearance.

AI aircraft stop at the last hold short where C and B meet near the Rwy 18/36 & 11/29 junction.

We have to place a HS node on Rwy 18/36 near it's junction with 7/25 - how close?

Got it. The Dev who owns this area is still on holiday. I'll see if I can get some guidance when he returns.

-Doug

 

[jvile]

Doug

When we study the visuals and apply the rules that we see for the majority of airports then from time to time for no apparent reason the rule is not enforced. We are talking about the HS node and its purpose at the entrance of a runway.

Reggie has found some airports as stated above that HS distance is not honorded as per our findings over the years. I in turn have also used the term "one off exception" when someone ask, why do I see this when the HS node is suppose to do this?

For every airport we found that does not honor the HS node distance correctly and locks the User/AI at the runway entrance point we also found the opposite to be true.

Daytona Beach, FL. (KDAB) is the opposite of what happens at KLAS. Anytime the user plane taxis along the parallel taxiway N of runway 7L/25R the ATC menu gives the option to contact Tower for takeoff. I agree these are few and far between but in the past when we get a understanding of HS node distance and apply the code rule I then have to say to those that ask,

"well out of 24,000 airports this is a one off exception to the rule".

Thats not always a negative when taxing and getting Tower to clear for takeoff before even getting close to the HS Node. In real world for many years the HS Node issue at Daytona Beach mimics exactly what I would do when departing KDAB. As I taxied the B727-200 down Taxiway N we would contact Tower and get immediate clearence for a no-hold takeoff. As I rounded the corner to runway 7L I was already spooling the engines to 20 percent so the taxi roll became the takeoff roll.

 

[GHD]

IWhat we typically do for taxiways that are not straight off the end of the runway:

distHSFromRwyCenterJunction = ((0.5 * RwyWidth) + TaxiWidth) / sin(meetAngle);

(meetAngle for a 90 degree junction would be 90)

This has nothing to do with aircraft radii or wingspans.

That doesn't really answer the question which was "What is the maximum distance from the runway to a hold-short node such that AI (and/or user aircraft) will be given clearance?"

If the taxiway enters via a blast pad, the angle may be zero in which case your formula breaks down.

George

 

[DougMatthews]

That doesn't really answer the question which was "What is the maximum distance from the runway to a hold-short node such that AI (and/or user aircraft) will be given clearance?"

If the taxiway enters via a blast pad, the angle may be zero in which case your formula breaks down.

George

In the zero angle case that formula does not apply. We try to push them back out of the flight path in those cases. I've mailed the Dev who owns this area requesting guidance on the maximum distance question. Once I hear back I'll post it.

-Doug

 

[DougMatthews]

Doug,

I wasn't clear enough.

We've been under the impression since Sept 2003 that a hold short node has to be within about 225 ft of the runway. Otherwise AI and user aircraft will not be able to contact the tower and ask for takeoff clearance.

We've seen many instances - like RODN Rwyu 9L and Rwy 9R in FS2004 where the hold shot node is less than 225 ft from the blastpad/ overrun - but more than 225 feet from the actual runway.

AI aircraft in FS2004 would not takeoff on these runways at this airport unless the nodes were moved to within about 225 ft of the actual runway. This also occured with user aircraft.

By that "rule", both AI and user aircraft should not be able to takeoff from Rwy 19R at KLAS. When they taxi to the hold short node on Taxiway J - that node is about 162 feet from the runway Taxipath / centerline on the blast pad. That node is about 375 feet from the edge of the runway.

When observing AI traffic, aircraft 15M and larger half wing span value will ask for takeoff clearance from that point. AI aircraft smaller than 15M will sit at the node and time out without asking for takeoff clearance.

With user aircraft - those under 13M in half wing span value do not get the option to request takeoff at the HS node. Some aircraft between 13M and 17M get the option at the HS node, some do not.

Testing a variety of default aircraft - the C-172 has to taxi onto the runway blast pad for about 100 feet from the junction before it has the option to request takeoff.

The default DC-3 - 16M - has to taxi just past the HS node.
The default CRJ - 13M - can request takeoff at the HS node.
The default B744 - 33M - can request takeoff almost 550 ft away from the runway, back on the west side of where Taxiway J changes to Taxiway H as it crosses Taxiway F.

All user aircraft test were done from parking spot N Parking 44 with the spot turned to heading 116.3 so it was a straight taxi out for user aircraft.

How close the HS node has to be to the runway part of a runway with a blast pad/ overrun is a very important item for people interested in AI. There are dozens of airports where the last taxiway joins on the blast pad / overrun.

There are also many situations like the default PADQ where takeoffs are often directed from Rwy 25 - however the default taxi route is "Taxiway F, Runway 7, Taxiway D, Taxiway C, Runway 36, Runway 7"

User aircraft never get the option to ask for takeoff clearance.

AI aircraft stop at the last hold short where C and B meet near the Rwy 18/36 & 11/29 junction.

We have to place a HS node on Rwy 18/36 near it's junction with 7/25 - how close?

So I spoke with the area owner. For FSX, buffer the aircraft bounding radius by 91.44 meters (300 feet). From the aircraft location, if the buffered radius intersects the runway pavement you should be able to request takeoff clearance.

I'm going to file a bug to do something smarter in the future.

-Doug