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Thread: KSLC Rwy 34R ILS

  1. #1
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    Default KSLC Rwy 34R ILS

    I have tried every which way I can think of to account for the SERIOUS drop in altitude that is required to make the approach at KSLC 34R (or L for that matter) when coming from the west (KOAK). As soon as you pass over the mountains to the west of the facility (at 12K ft.) you have a really short base and final to drop down to the assigned altitude of 6,100 ft at the FAF. It can't be done in my opinion....at least not on FSX. Only time I did it successfully was by the seat of my pants (glideslope? what glideslope?) when I slammed into the runway at about 180 kts. like I was hitting the deck of a carrier. Flying a GS-550 but I have tried it in the CRJ-700 & 737 to no avail. Even when you go missed ATC just routes you back the same way.

    Any real-life pilots that can solve this puzzle for me? How do they route you in the real world? I would greatly appreciate it.

  2. #2

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    Looking at the chart, you need to come from the south (Fairfield VOR IAF).
    https://skyvector.com/files/tpp/1806/pdf/00365IL34R.PDF

    You may want to cancel FSX ATC, and do your own thing.

    Wim

  3. Default

    Option one: fly over runway while descending. Fly right base descending further to 2000AGL. Fly right downwind, while slowing way down. Right base (keeping mountain to your left, don't crash into it please.). Turn to final and intercept Glideslope from below.

    Option two. To try straight in approach. Fly a slow prop. And extend flaps while still over the mountain. Slow already while over mountain to 60kt or so.
    Why? For every vertical speed it goes that the lower the horizontal speed, the steeper your descent-angle will be. (I'LL add an image later.).

    Image:
    (beta is much steeper then angle alpha. Both flown at same vertical speed. (900 feet per minute) but at different horizontal speeds (respectively 170 and 60 Nautical miles per hour).
    Click image for larger version. 

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    Third option. Change the weather (opposite wind direction) so a different runway is active. Or divert to an alternate airport.
    These situations occur in real world airports too. One way in, one way out.

    Option 4. Use ADE to close those runways off for landings from that end. Seems sometimes that is not fully possible though.
    Option5. Use ADE to edit the airport so all runways are always active. Then you can land from any direction you want.
    Last edited by rick; 06-10-2018 at 07:21 PM.

  4. #4
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    Default

    Thanks to both of you and a special thanks to il88tp for the very detailed explanation.

    This issue points out one of the inherent problems with FSX's ATC program. It just doesn't account for the limitations of pilots and aircraft when it comes to asking the impossible.

    I think next time I'll just ask for a different runway.

  5. Default

    Despite looking at the gauge and the name "vertical speed" many don't realize that it is simply a speed. Just as airspeed is.


    60 knots
    is 60 Nautical Mile per hour
    (means you travel 60 Nautical miles in one hour)
    is 60 times 1852 meters in one hour
    is 60 times 1852 meter in 60 minutes
    (3.2 feet to a meter)
    (one NM, 1852 meters, times 3.2 = 5926 feet)
    is 60 times 5926 feet in 60 minutes
    is 60 times (5926/60) feet per minute
    is 60 times 100 ft/min
    is 6000 ft per minute

    So 60 knots equals 6000 feet per minute.
    (and 900 feet per minute is the same as 9 Knots.)

    Now back to the situation.
    lets say 60 knots groundspeed and VS is 800 ft/min
    We now know that means VS is 9 Kt
    So angle beta can be calculated now.
    Using horizontal and vertical distances.
    In one hour, the plane would:
    descend 9 NM, and move forward 60NM
    tangent of Beta is: 9/60
    (this is 0.15)
    Beta is inverse tangent of 0.15
    is an angle of 8.5 degrees.
    (or 9.47%)

    should be plenty steep, and, in a beech baron or Cessna you can do that without speed increasing in
    the descent. Even if it does increase, flaring is much easier in those aircraft and you can float longer.

    I calculated the angle by dividing "distances traveled if speeds were continued for one hour"
    But that is not needed really.
    As long as the speeds are converted to the same units, for example both in "Knots", you can just divide vertical speed by groundspeed. And take the inverse angle to get the descent angle.

    (Use the "Grad" setting on your calculator to calculate the angle in %
    use the 'Deg' setting to calculate the angle in degrees.)

    Now lets see what a Boeing 747 would need to do to get that same angle.
    At a speed of 180 knots...
    VS/GS=0.15
    (we get the 0.15 from before, but you can also get it by setting the calculator to 'Grad" and typing 'tangent 9.47')
    So...
    VS/180=0.15
    VS=0.15 times 180
    VS=26.97 (thats in Knots, remember)
    so that means to get that same angle while flying 180 knots in the 747, you would
    need to descend at 26.97 times 100 = 2697 feet per minute

    (by the way, doing 180 GS in a Cessna, you would require the same VS to make that angle....2697 feet per minute)

    In a Cessna or Beech, that angle can be made. by flying slowly. It's on the limit, but you can pull it off.
    In a 747, not so much. You can try to pull of the angle, but converting the descent into level flight you
    gain so much speed you can't stop before the end of the runway.


    Edit, I see now that the image already made things clear. Nice!
    Happy Flights,
    il.
    Last edited by il88pp; 06-10-2018 at 06:09 PM.

  6. #6

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    Quote Originally Posted by BlueAero View Post
    I have tried every which way I can think of to account for the SERIOUS drop in altitude that is required to make the approach at KSLC 34R (or L for that matter) when coming from the west (KOAK). As soon as you pass over the mountains to the west of the facility (at 12K ft.) you have a really short base and final to drop down to the assigned altitude of 6,100 ft at the FAF. It can't be done in my opinion....at least not on FSX. Only time I did it successfully was by the seat of my pants (glideslope? what glideslope?) when I slammed into the runway at about 180 kts. like I was hitting the deck of a carrier. Flying a GS-550 but I have tried it in the CRJ-700 & 737 to no avail. Even when you go missed ATC just routes you back the same way.

    Any real-life pilots that can solve this puzzle for me? How do they route you in the real world? I would greatly appreciate it.
    https://skyvector.com/files/tpp/1806/pdf/00365WAATS.PDF

    Click image for larger version. 

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    Click image for larger version. 

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    Try this procedure and if the aircraft you are using does not have the capability of displaying such just insert the way-points into the flight plan that I have shown. It is one way of doing it. And it works.
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  7. #7

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    HAHAHA You should try to land on 17 from the East coming in over the mountains. I do it all the time with FS's crappy ATC, but I know I'll be too high so slow way down by Ogden before my turn onto intercepting the LOC.

    To me, flying into 34 is easier. Just reduce your speed and do a bit more of a steep decent when ATC tells you to descend. I figure you typically have to be around 2,000' AGL so plan accordingly.

    Chicago for me would have to be the worst. I'm at 9,000 MSL and the damn ATC tells me I'm clear to land. THE HELL I AM! So I cancel ATC and do my own thing. This is the default KORD.

    All about experience I guess. And I'm coming in at mach speed form FL500. I just step down the speed at certain altitudes and adjust VS as necessary. Never crashed yet unless I was dicking around at Area-51.
    Last edited by CRJ_simpilot; 06-11-2018 at 09:15 AM.

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  8. #8
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    Default

    Wow. All of your input is great information and makes total sense to me. Thanks so much, guys. You don't realize how much I appreciate it!

    Every time I start to think I'm becoming a hotshot computer pilot something happens to make me realize how much I have yet to learn about flying.

  9. #9
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    Default

    As soon as you pass over the mountains to the west of the facility (at 12K ft.) you have a really short base and final to drop down to the assigned altitude of 6,100 ft at the FAF. It can't be done in my opinion....at least not on FSX.
    You've missed an important point, the IAF (Initial Approach Fix), FAIRFIELD VOR at the bottom (south) of the chart. You don't just drop in at the FAF, and that is especially true for this approach (plus many others with high terrain). The IAF may seem out of the way, but that's the way real aircraft have to do it, and that's what's needed to make a decent approach in the sim, as well. And notice the vertical profile which shows that you have 9.1 nautical miles (NM) to descend from 9,000 feet to 6,100 feet, and that is AFTER 5.5 NM to descend from 11,000 feet to 9,000 feet.

    So if the approach plate that Wim linked to is followed you'll see that it is not a "SERIOUS drop in altitude that is required to make the approach at KSLC 34R," but rather a much longer distance in order to avoid problems with the terrain. That's why Wim said you need to come in from the south via the IAF.

    That's why they publish procedures and that's (part of) why instrument pilots need so much training, so they can read and use the various applicable charts.

    Of course in the sim you can avoid all that and do whatever you like, but don't complain about the approach itself (or at least not for the wrong reasons).

    Larry N.

    As Skylab would say:
    Remember: Aviation is NOT an exact Science!

  10. #10

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    Quote Originally Posted by lnuss View Post
    You've missed an important point, the IAF (Initial Approach Fix), FAIRFIELD VOR at the bottom (south) of the chart. You don't just drop in at the FAF, and that is especially true for this approach (plus many others with high terrain). The IAF may seem out of the way, but that's the way real aircraft have to do it, and that's what's needed to make a decent approach in the sim, as well. And notice the vertical profile which shows that you have 9.1 nautical miles (NM) to descend from 9,000 feet to 6,100 feet, and that is AFTER 5.5 NM to descend from 11,000 feet to 9,000 feet.

    So if the approach plate that Wim linked to is followed you'll see that it is not a "SERIOUS drop in altitude that is required to make the approach at KSLC 34R," but rather a much longer distance in order to avoid problems with the terrain. That's why Wim said you need to come in from the south via the IAF.

    That's why they publish procedures and that's (part of) why instrument pilots need so much training, so they can read and use the various applicable charts.

    Of course in the sim you can avoid all that and do whatever you like, but don't complain about the approach itself (or at least not for the wrong reasons).
    +1

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