FS9 to FSX

[Mace 1,924]

>Further studies based on Reggie's find>>If the entrance taxiway is 90 degrees to the runway the new>spec for a holdshort node is 300 ft from the side of a>runway.>>All of this changes based on many factors if the entrance>taxiway is at a angle to the runway. Now the holdshort can be>moved further away.>Did you find that the size of the aircraft had any effect on this?Last night I observed a 752 hold short at KDFW on the west two parallels; it calmly waited for the departing MD8x's and 738's, and then proceeded to cross as if nothing was out-of-sorts.This was at a hold short that exceeds the old limit. The taxiways enter at 45 degree angles or so.More study on my part is needed, one aircraft observed is not enough.RhettAMD 3700+ (@2585 mhz), eVGA 7800GT 256 (Guru3D 93.71), ASUS A8N-E, PC Power 510 SLI, 2gb Corsair XMS 3-3-3-8 (1T), WD 150 gig 10000rpm Raptor, WD 250gig 7200rpm SATA2, Seagate 120gb 5400 rpm external HD, CoolerMaster Praetorian

[jvile 1]

>>Did you find that the size of the aircraft had any effect on this?>I have not studied size aircraft yet. Reggie is still working out that maze.>>Last night I observed a 752 hold short at >KDFW on the west two parallels; it calmly >waited for the departing MD8x's and 738's, >and then proceeded to cross as if nothing >was out-of-sorts.>That has nothing to do with a holdshort node but who has owership of the runway.For departing planes the owership occurs at state Takeoff 1. Any plane that needs to cross the runway will be told to hold. This may occur in many different places along a taxiway. The work around is to stack overlay or diamond the taxiway where it crosses the runway so ATC is fooled into thinking the taxiway is not crossing a runway and no hold command is issued (see my KMIA or KMSP).For Arrival planes the owership of a runway occurs at the FAF. Every plane that needs to cross the active runway is given a hold command by ATC unless we fool the taxiway network.Each runway has a entrance hold short node at each end which ATC sends the departure plane to. These hold shorts nodes differ from the ones that are in place for any plane that exits the runway after landing. Many times I will move the exit runway holdshort node to the paralleling taxiway which maybe 1000 ft from the side of the runway texture. When the plane exits the runway it continues to taxi to the first hold short node it finds and then stops to change states and get from ATC instuctions for what taxiway network it will use to the parking spot.The width of the runway texture is very important for ATC. Many delete the runway texture or decrease the width to try and make the runway invisible. If the runway texture width is decreased to less then the main gear contact points or made invisible ATC does not know where the arrival plane is when it lands. You will hear ATC tell the user or the AI to contact ground immediatly after touchdown and not wait until the main gear contact points have cleared the runway texture. The runway texture also has the embedded touchdown point for the arrival. Many 3rd party AI fight the touchdown point because the FDE designer wants flair. Some AI Planes FDE's are tweak so bad the AI goes around time after time because of too much flair and overshoots the invisible touchdown point in the runway texture. I say it is in the runway texture but it is also a rho calculation from the FAF to the runway texture invisible point of touchdown. The Traffictoolbox.dll will capture the touchdown point of the runway if you have zoom set correctly but the draw to touchdown only exist for about one second so you have to watch quickly.The ideal is set the FAF so the .dll gives the AI a 3 degree slope angle to the touchdown point in the runway texture. If you move the FAF back to 10 miles from touchdown the .dll calculates a new rho and the FPM descent is lessened on the approach given the FDE is engineered properly and does not fight the slope angle. The hardfloor hardcode fixed altitude at the FAF is very important if no ILS and ILS approach code exist. Many AI Planes are seen to roll to the runway because the sinkrate of the AI when gear deploys falls through the hardfloor and the AI cannot recover back to the hardfloor.I probably typed more then you wanted to know.

[Mace 1,924]

>>>>Last night I observed a 752 hold short at >>KDFW on the west two parallels; it calmly >>waited for the departing MD8x's and 738's, >>and then proceeded to cross as if nothing >>was out-of-sorts.>>>>That has nothing to do with a holdshort node but who has>owership of the runway.>Yes but doesn't the hold short distance still apply?It was everyone's (former) understanding that if this hold short is more than 225 feet from the rwy, the AI aircraft that is holding short could get stuck there, and disappear after the time-out period elapsed, irregardless of who has ownership over the rwy at any given time.This 752 should have, by all rights, been stuck there, even after the departing aircraft had passed by. Yet it did not get stuck.This dovetails with what you and Reggie were talking about--that the long-established hold-short radius seems to be different in FSX.Why can't Microsoft publish a white paper on this internal .dll info with all of this data? It would save a lot of effort!>>I probably typed more then you wanted to know.> No you did not, thanks for that information. Some of it I knew already and had put into practice but some was new and I will squirrel it away in the database I have.RhettAMD 3700+ (@2585 mhz), eVGA 7800GT 256 (Guru3D 93.71), ASUS A8N-E, PC Power 510 SLI, 2gb Corsair XMS 3-3-3-8 (1T), WD 150 gig 10000rpm Raptor, WD 250gig 7200rpm SATA2, Seagate 120gb 5400 rpm external HD, CoolerMaster Praetorian

[jvile 1]

>>>>Last night I observed a 752 hold short at >>KDFW on the west two parallels; it calmly >>waited for the departing MD8x's and 738's, >>and then proceeded to cross as if nothing >>was out-of-sorts.>>>I am assuming a B752 held at a crossing intersection somewhere mid point of a runway at KDFW and waited until the runway was clear until proceeding to the Gate. If that is true thenThe B752 held at the active because ATC ground told it to and not because there was a hold short node. Once the last plane departed and was told to contact departure then the runway was released and ATC ground will tell the B752 to continue taxing across the runway. That is not where the problem comes from when talking about a AI getting stuck (see below).My studies show that a hold short node is a automatic stopping point for AI entering a runway for takeoff or exiting a runway. ATC Ground does not tell a taxing/departing Plane to 'stop' and contact Tower when it reaches the very end hold short for the runway. ATC Tower does not tell the arrival plane that has taxied off the active to 'stop' when it reaches the holdshort and contact ground. The AI Plane knows when it reaches the hold short and stops. ATC only says contact ground on arrival and for departure the AI once at the hold short contacts tower. The Hold short node is seen as a automatic stopping point for departing and arriving airplanes and not for AI that are taxing from one point to another. It is ATC Ground that stops and starts plane movement if any conflict between AI to AI/User/ground support autogen vehicles is seen as a possible interference.When listening to the Ground Freq it is ATC that tells the AI to stop when the ownership of the runway belongs to the departure or arriving plane. If the AI stops within the hold short spec radius that is coincidental. You can change the holdshort nodes to normal nodes (not the end taxiway to runway node) as a test and ATC Ground will still tell a AI plane to stop and not allow a crossing if the Active is owned by another plane. There are many airports/taxiways where as ATC will stop a AI plane that is taxing to the gate (which has to cross the active) long before it reaches the runway holdshort. The opposite is true at very busy Ground ATC activity where the AI crossing the runway is told to stop by ATC too late. The AI is then seen as a stop plane halfway across the runway until the departing plane releases ownership (KMIA) then Ground tells the stop AI to continue. Because KMIA 8L/27R, 8R/27L runways are so close together I fixed that problem with my FS9 and FSX KMIA using the diamonds. Stuck AirplaneThis was a problem in FS9 but could also be a problem in FSX (Reggie's studies) based on size aircraft compounded by the new holdshort distance code.When we were designing AFCAD2 with Lee it was Tom Gibson if memory serves me right that studied the stuck behavior that only occured at the entrance of the runway for takeoff. We agreed to add a line entry in the AFCAD2 documentation that says>>>>> QuoteAnother problem can occur when two or more aircraft line up at a hold-short node for departure, the aircraft at the front of the line may get clearance and proceed to take off, but the aircraft behind him may become stuck. This problem is more likely to occur with smaller aircraft. This can be prevented by placing a normal (blue) node or an ILS hold-short node just behind the hold short node. Some experimenting has shown this second node should be no more that 70 feet (21.3 m) behind the hold-short node to work with all sizes of aircraft. As a rule of thumb, just place the nodes so they touch or overlap slightly.>>>>> QuoteThis was a problem in FS9 at KATL runway 8R and KLAS when I applied my crosswind technique to runway 01L from the 07's. The additional normal node behind the hold short node solved the stuck AI issue for those airport runways. There is another problem that causes stuck AI Planes and that is when the airport designer uses a FSX Utility that destroys the taxiway segmentation. We at ADE developed a Utility that not only keeps segmentation in place but allows the airport designer to add additional segmented taxiways. If a AI Airplane has a problem and gets stuck somewhere along its assigned taxiway network route to and from a runway we add additional segments. This also allows ADE to increase the .70 AI throttle value (trafficScalar) up to its max limit of 1.00. The AI thottle value was hidden in FS9 but ACES exposed it in FSX. It's up to the Flightplan Designer to know how the throttle value impacts taxi/stuck AI Planes when they compile a FP with the FSX trafficDatabaseBuilder compiler. Just one of the reasons we stayed away from the FS9 trafficDatabaseBuilder compiler an used Lee's TTools compiler. The stock FSX KBHM has this AI stuck problem along both sides of the 06/24 runway that have the parallel taxiways. I segmented each section of the taxiways with ADE. No more stuck AI to and from the runway along each paralleling taxiway.

[Mace 1,924]

Indeed the 752 at KDFW was holding due to ATC commands, and you are correct in assuming it was mid-runway. I now see that this is a different animal than the AI getting stuck that you are referring to.It is also different than the other "stuck AI" issue, which is the one related to ground service vehicles in FSX.For FS11, I still want Microsoft to release a White Paper (or in the SDK) that gives us all of this information without us having to do all of this research. :)RhettAMD 3700+ (@2585 mhz), eVGA 7800GT 256 (Guru3D 93.71), ASUS A8N-E, PC Power 510 SLI, 2gb Corsair XMS 3-3-3-8 (1T), WD 150 gig 10000rpm Raptor, WD 250gig 7200rpm SATA2, Seagate 120gb 5400 rpm external HD, CoolerMaster Praetorian