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pager94

Stacked holding pattern / FMS Question

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Hi All,When I took my IFR checkride around KPHX (by the way AZ is the worst place to get IFR training, need to go to CA for clouds and IFR conditions) the designated examinaer (DE) introduced me into a stacked holding pattern, commonly used at high density airports (KLAX, KJFK, KORD, etc). Essentially, upon entering a highly stacked holding pattern outside the airport each aircraft stepped down one level in the stack until it was their turn to shoot the approach. Does anyone know if the PMDG 737NG FMS will stimulate this downstepping in the holding pattern automatically or will the hold be consistent but the step wise drop down the stack will be manual via MCP? Anyway, while were all in a stacked holding pattern waiting for final approach clearance for the PMDG 737NG, I thought I would share some shots from my recently aquired A2A Piper Cub. I took her out for some spin testing over the Grand Canyon MegaScenery Style and she handled them perfectly. Does anyone know if the PMDG 737NG will be certified for spins? :( Next a nice power ON steep stall with constant hard rudder, result --> Nice snap roll, OUCH........................... my neck hurts :( Cheers,BillyBob

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I've often wondered this myself. I am from the Atlanta area so whenever I fly into ATL we almost always get put into a hold or get vectored off some random "tangent" for spacing.Best Regards,

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If I understand the question correctly, descents in a holding pattern are done only on instruction from ATC. The pilots, getting a clearance to a lower altitude, would select the new altitude in the MCP and down they go. As the planes on the bottom are steered out of the holding pattern and vectored for the approach, the higher aircraft are stepped down on by one by ATC. On a clear day, the stack of jets makes for an impressive sight for pilots and passengers. Hope your checkride went smoothly.

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If I understand the question correctly, descents in a holding pattern are done only on instruction from ATC. The pilots, getting a clearance to a lower altitude, would select the new altitude in the MCP and down they go. As the planes on the bottom are steered out of the holding pattern and vectored for the approach, the higher aircraft are stepped down on by one by ATC. On a clear day, the stack of jets makes for an impressive sight for pilots and passengers. Hope your checkride went smoothly.
Yes, it went smoothly. I got my IFR rating without going through 1 cloud. LOLBut I was asking if the FMC has the capacity, once IN the hold, to step down via VNAV or will it require a manual descent via MCP / FLCH for each step down?BB

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There's a target altitude in the hold page of the FMC for what I know

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There's a target altitude in the hold page of the FMC for what I know
You still have to put the altitude on the mcp. You would most likely be in LVL CHG or V/S in the hold.JackColwill

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You still have to put the altitude on the mcp. You would most likely be in LVL CHG or V/S in the hold.JackColwill
Yeah, it works like the speed/altitude restriction in a waypoint right? you still need to set the mcp altitude to the hold assigned target altitude or lower (if descending) for the VNAV path to comply.So even if it's not normal, it can be flown in VNAV. correct?

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ATC will assign a level that ensures 1000FT separation between other aircraft in the stack. It's best that you use V/S and select a decent rate (500-800fpm) so that you don't waste the controller's time. It is not safe to hope that VNAV will some how coordinate with other aircraft to prevent a collision.CheersNick Jones

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Yeah, it works like the speed/altitude restriction in a waypoint right? you still need to set the mcp altitude to the hold assigned target altitude or lower (if descending) for the VNAV path to comply.So even if it's not normal, it can be flown in VNAV. correct?
Well not so sure. Since Jack said you have to be in LVL CHG or VS mode, you are not in VNAV mode, so based on that I would say it cannot be flown in VNAV.Maybe someone can helps us further here ? I am curious now...

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I don't think Jack meant that VNAV isn't possible, just that the standard way of doing it at his airline is to use LVL CHG or V/S. Any use of VNAV would be VNAV SPD mode anyway, which is almost identical to LVL CHG basically (just the FMC's calculated speed vs. the pilot's MCP selected speed). I'd think you could edit the altitude on the HOLD page, roll the MCP down to it and engage a VNAV SPD descent, but I could very well be wrong.Good question by the way - I definitely don't know the answer myself...

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Regarding the vertical modes:From an ATC perspective, if we're stacking holds, we have a lot of traffic. If we clear a lower level, expect we're bringing in someone to take your spot. That being said, whatever gets you off of that altitude of the hold and down to the next faster is much preferred.

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Ok... curiosity got the better of us here - one of our tech team members tried this in a Level-D NG sim this morning. You actually cannot do it in VNAV period. Changing the altitude data doesn't create or update a new hold in the FMC. It must be done in LVL CHG or V/S.Case solved. tongue.gif

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Ok... curiosity got the better of us here - one of our tech team members tried this in a Level-D NG sim this morning. You actually cannot do it in VNAV period. Changing the altitude data doesn't create or update a new hold in the FMC. It must be done in LVL CHG or V/S.Case solved. tongue.gif
Thanks Ryan for checking it. That's a surprise to me. Ok, I have no idea of real life operations, but you can do it in the PMDG MD11, so thought that would be the case for the Boeings too. It's been a while since I last flew the 744 but I'll have to try it there

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But would changing the hold altitude in the FMC cause a change in best holding speed?

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But would changing the hold altitude in the FMC cause a change in best holding speed?
For what I know, in the PMDG MD11 it doesn't change the speed. You can add altitude targets (At or Above/ At or Below or exactly at) and the leg time and direction of turn.You can obviously change the speed going to V/S though

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curiosity got the better of us here - one of our tech team members tried this in a Level-D NG sim this morning.
Connections FTW!

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In the 744 I was able to set a speed/altitude restriction for the hold and fly it in VNAV. I'm not disputing anything, just saying

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Booking time in a Level-D sim to answer a forum post for a product that isn't released yet...now THAT'S customer support!

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Booking time in a Level-D sim to answer a forum post for a product that isn't released yet...now THAT'S customer support!
I don't think its called booking when you just casually hop in just any old morning. I think a better name would be lucky!

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Ok... curiosity got the better of us here - one of our tech team members tried this in a Level-D NG sim this morning. You actually cannot do it in VNAV period. Changing the altitude data doesn't create or update a new hold in the FMC. It must be done in LVL CHG or V/S.Case solved. tongue.gif
Short of taking a real one up for a fly about to try it, I think that's probably the best forum query reply anyone could ever hope for :( Al

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Now you can understand the resources available to make this product the best ever for FS!JadkColwill

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any normal developer would have had a quick look in the manual/specs to see what would happen, but not PMDG!!!! they try it in the real sim!!

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Ok guys, I have an update/retraction here:Turns out our tech team member (who is not Jack in this thread btw), was rushed the other morning and didn't try exactly what was being discussed here. He did try it exactly this morning and we now have video of exactly what it does (can't show it, sorry) - you actually CAN do it in VNAV - here's exactly what happens:- You're holding level in VNAV PTH and you input a new altitude into LSK 1R and exec.- As soon as you roll the MCP altitude down toward that new altitude the plane goes to VNAV SPD and performs an idle descent at best hold speed.- New best hold speed is calculated as soon as you put the new altitude in.That's the real story, sorry for the false alarm yesterday. Expect it to behave this way in the NGX.

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Ok guys, I have an update/retraction here:Turns out our tech team member (who is not Jack in this thread btw), was rushed the other morning and didn't try exactly what was being discussed here. He did try it exactly this morning and we now have video of exactly what it does (can't show it, sorry) - you actually CAN do it in VNAV - here's exactly what happens:- You're holding level in VNAV PTH and you input a new altitude into LSK 1R and exec.- As soon as you roll the MCP altitude down toward that new altitude the plane goes to VNAV SPD and performs an idle descent at best hold speed.- New best hold speed is calculated as soon as you put the new altitude in.That's the real story, sorry for the false alarm yesterday. Expect it to behave this way in the NGX.
Wow your attention to detail is just stunning. Very few would have pick up on this!.

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