Genius12
Topic Author
Posts: 216
Joined: Wed Aug 08, 2007 3:49 am

FSX ILS Approach - Coming Down Too Early

Wed Dec 19, 2007 8:34 pm

I don't know why this is happening - I'm using the default FSX B737-800, flying from Southampton (UK) to Bristol (UK). Everything is perfect up until about 3 miles from the runway at Bristol.

I engage onto the approach in good time with the flaps set at the correct intervals, and then gear down. The ILS lines up perfectly with the runway heading. But then at about 2-3 miles from the runway, the plane is too low and touches down!

The ILS system seems to be bringing the plane down too early. Like I say, the heading is spot on though.

Please can anyone help with this problem? It happens at any airport I fly to.

Thanks.  Smile
 
scoliodon
Posts: 212
Joined: Mon Oct 31, 2005 4:15 pm

RE: FSX ILS Approach - Coming Down Too Early

Wed Dec 19, 2007 11:24 pm

Hi Genius12,

The APP mode in autopilot locks only the heading, tracking the runway centerline. It does not manage glideslope info.
So, it takes care of horizontal orientation, vertical orientation is still in your hand.
So you have to increase/decrease power as required to maintain your glidepath.

Good luck!


Regards,
Balki
JFK-LGA-EWR-DTW-IND-PHX-CLE-SFO-LAS-SEA-ORD-MCO-MIA-DFW-ATL-CDG-FRA-BOM-MAA-DEL-TRZ-DXB-CLT-CVG-DEN-MSP
 
dw747400
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Joined: Wed Aug 15, 2001 8:24 am

RE: FSX ILS Approach - Coming Down Too Early

Thu Dec 20, 2007 2:51 am



Quoting Scoliodon (Reply 1):
It does not manage glideslope info.

It does on my FSX! Actually, the 737 flies pretty much the same as the STEC 55-X Autopilot I've used... looks different, but the functions are pretty much the same.
CFI--Certfied Freakin Idiot
 
ShyFlyer
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Joined: Fri Jun 19, 2009 11:38 pm

RE: FSX ILS Approach - Coming Down Too Early

Thu Dec 20, 2007 6:32 am



Quoting Scoliodon (Reply 1):
The APP mode in autopilot locks only the heading, tracking the runway centerline. It does not manage glideslope info.

It's supposed to. Using the approach mode on the autopilot should track the localizer (not the heading) and the glideslope of the ILS, once each is intercepted.
I lift things up and put them down.
 
David L
Posts: 8547
Joined: Tue May 18, 1999 2:26 am

RE: FSX ILS Approach - Coming Down Too Early

Thu Dec 20, 2007 1:49 pm



Quoting Scoliodon (Reply 1):
The APP mode in autopilot locks only the heading, tracking the runway centerline. It does not manage glideslope info.

As others have said, APPR mode will track the localiser and glideslope. It's the LOC mode that will only track the localiser.
 
Genius12
Topic Author
Posts: 216
Joined: Wed Aug 08, 2007 3:49 am

RE: FSX ILS Approach - Coming Down Too Early

Thu Dec 20, 2007 3:58 pm

Thanks for your replies.

So if approach mode does control vertical as well as horizontal, why am I coming down too early?

Thanks.
 
scoliodon
Posts: 212
Joined: Mon Oct 31, 2005 4:15 pm

RE: FSX ILS Approach - Coming Down Too Early

Thu Dec 20, 2007 5:09 pm

Thanks for the clarification guys!
I said that due to my FS2004 exp. with GPS autopilot APP mode enabled.

Or is there a way around there too?
JFK-LGA-EWR-DTW-IND-PHX-CLE-SFO-LAS-SEA-ORD-MCO-MIA-DFW-ATL-CDG-FRA-BOM-MAA-DEL-TRZ-DXB-CLT-CVG-DEN-MSP
 
ShyFlyer
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Joined: Fri Jun 19, 2009 11:38 pm

RE: FSX ILS Approach - Coming Down Too Early

Thu Dec 20, 2007 5:18 pm



Quoting Scoliodon (Reply 6):
Or is there a way around there too?

If you have the GPS linked to the autopilot, then you will not get vertical guidance, unless you input a lower altitude into the autopilot and adjust the vertical speed yourself. De-selecting the GPS as your navigation source will allow you to navigate using ground based navaids.
I lift things up and put them down.
 
Genius12
Topic Author
Posts: 216
Joined: Wed Aug 08, 2007 3:49 am

RE: FSX ILS Approach - Coming Down Too Early

Thu Dec 20, 2007 8:30 pm

I think I've solved it! I was using the autothrottle for too long, I think. Switiching it off about 3miles away from the runway and then manually controlling worked - I've just tried Glasgow-Edinburgh as a test route, and I touched down perfectly using ILS at the end of a IFR flight.
 
David L
Posts: 8547
Joined: Tue May 18, 1999 2:26 am

RE: FSX ILS Approach - Coming Down Too Early

Thu Dec 20, 2007 10:41 pm



Quoting Genius12 (Reply 8):
I think I've solved it! I was using the autothrottle for too long, I think.

Hmm... I'm sure I often left the auto-throttle on down to about a couple of hundred feet and it worked fine. I haven't "flown" a 737 for a couple of years, though, and that was the PMDG one. I guess the default 737 auto-throttle is "a bit dodgy", then.  Smile
 
cptspeaking
Posts: 567
Joined: Mon Apr 24, 2006 2:49 pm

RE: FSX ILS Approach - Coming Down Too Early

Sat Dec 22, 2007 12:23 am

A couple note-worthy things about FS ILS approaches and autopilots/throttles.

First, in FS, in order to intercept the glideslope, you need to intercept from below. If you come down onto the glideslope, the autopilot will not intercept it, so make sure you're down in plenty of time.

In FS default aircraft, there is no autoland functionality. So don't expect the aircraft to flare and rollout on its own. Instead, it'll just drop right onto the runway, which in a transport category aircraft will generally be in the range of 6-700 fpm. Ouch!!  eek  Autoland capability is possible in several add-on aircraft including PMDG's 737 and 747, Level-D Simulation's 763ER, and the PSS Airbus series.

Also in FS default aircraft, the autothrottles operate completely separate from the autopilot, so if you do leave it on for the approach, be sure to flip it off before you get to the flare, otherwise it'll keep on trucking along at approach speed. In add-on aircraft with the autoland capability, the autothrottles will pull the levers to idle when the flare mode activates.

Hope this information helps solve your troubles...happy flying and Merry Christmas!!

Your CptSpeaking santahat 
...and don't call me Shirley!!
 
Genius12
Topic Author
Posts: 216
Joined: Wed Aug 08, 2007 3:49 am

RE: FSX ILS Approach - Coming Down Too Early

Sat Dec 22, 2007 4:01 pm

Thanks everyone, all your help much appreciated.
 
Mir
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Joined: Mon Jan 05, 2004 3:55 am

RE: FSX ILS Approach - Coming Down Too Early

Sun Dec 23, 2007 6:36 am



Quoting CptSpeaking (Reply 10):
In add-on aircraft with the autoland capability, the autothrottles will pull the levers to idle when the flare mode activates.

Except the Airbus, which requires you to bring them to idle yourself (move them back one detent from CLB to IDLE). If you are a retard and forget, the plane will remind you of that.  Wink

-Mir
7 billion, one nation, imagination...it's a beautiful day
 
UA772IAD
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Joined: Sat Jul 10, 2004 7:43 am

RE: FSX ILS Approach - Coming Down Too Early

Sun Dec 23, 2007 9:39 am



Quoting Mir (Reply 12):

Except the Airbus, which requires you to bring them to idle yourself (move them back one detent from CLB to IDLE). If you are a retard and forget, the plane will remind you of that. Wink

Actually in real life, the Airbus (and Boeing) models are supposed to do this automatically, in case the pilot is a "retard". I've never tested it in my add on's though (PMDG 747, Level D 767, PSS 777, Wilco Airbus), as I'm afraid to botch my flights!
 
David L
Posts: 8547
Joined: Tue May 18, 1999 2:26 am

RE: FSX ILS Approach - Coming Down Too Early

Sun Dec 23, 2007 12:00 pm



Quoting UA772IAD (Reply 13):
Quoting Mir (Reply 12):

Except the Airbus, which requires you to bring them to idle yourself (move them back one detent from CLB to IDLE). If you are a retard and forget, the plane will remind you of that. Wink

Actually in real life, the Airbus (and Boeing) models are supposed to do this automatically, in case the pilot is a "retard".

It's my understanding that the Airbus auto-thrust will bring the engines to idle during the flare but the levers have to be moved so that the engines don't spool up again when the auto-thrust disengages after landing. I know it seems like a Bad Idea to some but the only people who seem to have a problem with it are those who've never flown a FBW Airbus.  Smile
 
Genius12
Topic Author
Posts: 216
Joined: Wed Aug 08, 2007 3:49 am

RE: FSX ILS Approach - Coming Down Too Early

Mon Dec 24, 2007 5:32 pm

For a B737-800, is the following landing checklist about right?

When cleared for ILS landing: Flaps 1 step, Speed 200kts, Engage onto approach
When 10nm distance: Flaps 2 more steps
When 09nm distance: Flaps 1 more step, Speed 180kts
When 08nm distance: Flaps 1 more step, Gear down
When 07nm distance: Flaps 1 more step, Speed 160kts
When 06nm distance: Flaps 1 more step
When 05nm distance: Flaps fully down
When at 300feet: Autopilot off, Autothrottle off, Engines idle
When touchdown: Airbrakes on/spoiler up, Reverse thrust, Brakes
When speed 50kts: Engines idle (reverse thrust off), Flaps up, Airbrakes off/spoiler down

Cheers  Smile
 
cptspeaking
Posts: 567
Joined: Mon Apr 24, 2006 2:49 pm

RE: FSX ILS Approach - Coming Down Too Early

Tue Dec 25, 2007 3:38 am



Quoting Genius12 (Reply 15):

Your distances look about right, but honestly, I fly approaches mainly based on the "feel" of it while taking into account speed limitations on the flaps and gear. If you're flying an ILS, you should be totally configured by the time you intercept the glideslope so all you have to do when you intercept is fly it down.

I wouldn't pull the throttles back until about 50 feet or so, at which point I would also start a smooth round out and flare. If you pull the throttles at 300 feet, you'll have a hard time making the runway. Also, as part of your approach checklist, I'd arm the auto-spoilers (Shift + /), which extends them automatically when the wheels touch the ground. That way, all you need to do when you touch down is apply the brakes (unless you've used the autobrakes) and reverse thrust.

Happy Flying!
...and don't call me Shirley!!
 
Maverick623
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Joined: Thu Nov 30, 2006 9:13 am

RE: FSX ILS Approach - Coming Down Too Early

Wed Dec 26, 2007 8:07 am



Quoting Genius12 (Reply 15):
For a B737-800, is the following landing checklist about right?

Just a few corrections:

Quoting Genius12 (Reply 15):
When at 300feet: Autopilot off, Autothrottle off, Engines idle

I wouldn't pull the throttle back till 50ft AGL, if you wanna make the runway relatively smoothly

Quoting Genius12 (Reply 15):
When 05nm distance: Flaps fully down

Add in Vref speed, I find 135-145kts good depending on how heavy the airplane is

Quoting Genius12 (Reply 15):
When speed 50kts: Engines idle (reverse thrust off)

60kts to be picky  wink 
"PHX is Phoenix, PDX is the other city" -777Way
 
cumulonimbus
Posts: 508
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RE: FSX ILS Approach - Coming Down Too Early

Wed Dec 26, 2007 9:52 pm

LOL Land that bad boy like I do! manually :P
 
NwAflyer07
Posts: 139
Joined: Sun Oct 14, 2007 3:00 pm

RE: FSX ILS Approach - Coming Down Too Early

Thu Dec 27, 2007 1:23 am



Quoting Cumulonimbus (Reply 18):
LOL Land that bad boy like I do! manually :P

lol amen to that
 
B727-200
Posts: 1008
Joined: Fri Nov 05, 1999 11:28 am

RE: FSX ILS Approach - Coming Down Too Early

Thu Dec 27, 2007 11:12 pm

I find I adjust the landing sequence according to the airport, weather conditions and aicraft weight. On an ILS approach I normally start pulling the speed back and dropping flaps once vectored to the intercept, unless there is poor weather/vis and/or mountains in the vicinity, in which I will bring the speed back much earlier.

One thing to make sure of if you are flying an ILS approach is to check that you have switched the NAV/GPS switch back to NAV. When I have been lazy and flown a leg on GPS I have sometimes forgot to switch back to NAV for landing and ended up not making the runway...

B727-200.
 
Halcyon
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Joined: Sat Jul 15, 2006 4:47 pm

RE: FSX ILS Approach - Coming Down Too Early

Thu Dec 27, 2007 11:38 pm



Quoting Cumulonimbus (Reply 18):
LOL Land that bad boy like I do! manually :P

Especially fun at Toncontin with the freeware scenery and accurate mesh.  Wink
 
cumulonimbus
Posts: 508
Joined: Sun Nov 08, 2009 8:13 pm

RE: FSX ILS Approach - Coming Down Too Early

Fri Dec 28, 2007 3:16 am



Quoting Halcyon (Reply 21):
Especially fun at Toncontin with the freeware scenery and accurate mesh

hah hah My machine can handle it top of the line baby!
 
KAUST
Posts: 605
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RE: FSX ILS Approach - Coming Down Too Early

Mon Apr 18, 2016 2:52 am

One add-on question (related!) tack on to this, if I may?

When on FSX:SE doing an ILS approach in the 737, I tend to run into two different problems:

1) Not intercepting localizer (I have altitude, airspeed, and nav/course settings correct. GPS/NAV is set by this time to Nav. Thinking is it either a matter of when I go to LOC/NAV on the autopilot, and/or not selecting correct activation setting in GPS? (Which of course in the sim acts as an FMS.

2) Nose pitches WAY too high up.


Ideas? Advices? Suggestions?



Thanks!
KAUST
"Houston, this is Apollo 8. We are now in Lunar orbit."

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