Simviation Forum - ILS Decision Height

Apr 28^th, 2011 at 9:00pm

bklaviator91 Offline
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I've been trying to figure out approaches this week, but I have one question that I still need help with...What is the decision height supposed to be for an ILS approach and what is "decided" at this altitude

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Reply #1 - Apr 28^th, 2011 at 9:30pm

DaveSims Offline
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Clear Lake, Iowa

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A typical Cat I ILS has a decision height of 200 feet. There are also Cat II and Cat III ILS approaches that reduce minimums even further, with Cat IIIB being an autoland, zero visibility approach. Flight sim really just models all ILS as Cat I.

What is decided is whether or not you have the runway environment in sight. If you reach decision height, and can't see the runway or approach lighting system, you are required to go around.

Dave

www.flymcw.com

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Reply #2 - Apr 28^th, 2011 at 11:54pm

Tyler012 Offline
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My Soul is in the Sky
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In regards to what Dave has said, You can also find the decision height on IFR plates (If you so choose to use them). It will be under the diagram, and be classified by aircraft class: A,B,C,D.

Just a sample of my personal art.

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Reply #3 - Apr 29^th, 2011 at 8:48am

Strategic Retreat Offline
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It doesn't give me any pleasure to correct you, Dave, but FS(anynumber) models all ILS effectively as a CAT III, with the sole exception of those ILS that are offset. Undecided

In fact, unless said ILS under FS is offset, you can use a plane that CAN Autoland to do just that with full success every time, everyhere, whilst in real life it would be a toss to autoland already on a CAT II, not to mention a CAT I. Tongue

There is no such a thing as overkill. Only unworthy targets.

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Reply #4 - Apr 29^th, 2011 at 9:21am

DaveSims Offline
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Clear Lake, Iowa

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Strategic Retreat wrote on Apr 29^th, 2011 at 8:48am:

It doesn't give me any pleasure to correct you, Dave, but FS(anynumber) models all ILS effectively as a CAT III, with the sole exception of those ILS that are offset. Undecided

In fact, unless said ILS under FS is offset, you can use a plane that CAN Autoland to do just that with full success every time, everyhere, whilst in real life it would be a toss to autoland already on a CAT II, not to mention a CAT I. Tongue

The trick is not many FS aircraft can accurately model an true autoland. True, you can leave the autopilot is APR mode all the way to the runway, but most aircraft will just fly into the runway.

Dave

www.flymcw.com

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Reply #5 - Apr 29^th, 2011 at 2:16pm

Strategic Retreat Offline
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DaveSims wrote on Apr 29^th, 2011 at 9:21am:

The trick is not many FS aircraft can accurately model an true autoland. True, you can leave the autopilot is APR mode all the way to the runway, but most aircraft will just fly into the runway.

Was talking about payware, there... or at the very least one of the few rare freeware that CAN, like the project Fokker, or a MD11 with the ACsoft panel... there was a panel for the MD80 that could too, even tough I've forgot its maker, and still there's around a multipurpose gauge that allows to every plane with both AP and AT to autoland, if installed... Cheesy

Anyway, given real autoland in a way or the other, ALL FS ILS can allow blind automated landing... beside the offset ones, of course. That makes them all by default CAT III. Cool

There is no such a thing as overkill. Only unworthy targets.

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Reply #6 - Apr 30^th, 2011 at 2:26pm

bklaviator91 Offline
Colonel

Posts: 15

Thanks all for the help!

This has really made my sim flights much more enjoyable Grin

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Reply #7 - May 2^nd, 2011 at 12:40am

F35LightningII Offline
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This is a bit unrelated to the main topic but I have found a way to make a default aircraft do a smooth landing on autopilot:

1) When APR hold is on and the aircraft is tracking the glideslope, set the ALT hold to 0 and the autopilot VS to -700 (don't engage it though)

2) Once about 100ft AGL, turn on ALT hold.

3) At 50ft, cut throttle and set your VS to -200

4) Once main gear touches down, disengage autopilot.

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Reply #8 - May 2^nd, 2011 at 9:41am

Strategic Retreat Offline
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F35LightningII wrote on May 2^nd, 2011 at 12:40am:

This is a bit unrelated to the main topic but I have found a way to make a default aircraft do a smooth landing on autopilot:

1) When APR hold is on and the aircraft is tracking the glideslope, set the ALT hold to 0 and the autopilot VS to -700 (don't engage it though)

2) Once about 100ft AGL, turn on ALT hold.

3) At 50ft, cut throttle and set your VS to -200

4) Once main gear touches down, disengage autopilot.

Was this awfully overcomplicated procedure created just not to have to touch the yoke? Huh

Do a favor to yourself and your skills and use the AP in landing only when really needed (low visibility, for example) and fly the other approaches yourself. The best parts of a flight, real or simulated, are take-off and landing, and if you willingly renounce to the best... what do you remain with? Wink

There is no such a thing as overkill. Only unworthy targets.

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