Genius12 From United Kingdom (England), joined Aug 2007, 115 posts, RR: 0 Posted (1 year 11 months 2 weeks 6 days 14 hours ago) and read 7973 times:
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.
Scoliodon From India, joined Oct 2005, 217 posts, RR: 0 Reply 1, posted (1 year 11 months 2 weeks 6 days 11 hours ago) and read 7954 times:
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.
Dw747400 From United States, joined Aug 2001, 978 posts, RR: 1 Reply 2, posted (1 year 11 months 2 weeks 6 days 7 hours ago) and read 7933 times:
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.
ShyFlyer From United States, joined Jun 2009, 213 posts, RR: 15 Reply 3, posted (1 year 11 months 2 weeks 6 days 4 hours ago) and read 7920 times:
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.
Genius12 From United Kingdom (England), joined Aug 2007, 115 posts, RR: 0 Reply 5, posted (1 year 11 months 2 weeks 5 days 18 hours ago) and read 7878 times:
Thanks for your replies.
So if approach mode does control vertical as well as horizontal, why am I coming down too early?
ShyFlyer From United States, joined Jun 2009, 213 posts, RR: 15 Reply 7, posted (1 year 11 months 2 weeks 5 days 17 hours ago) and read 7871 times:
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.
Genius12 From United Kingdom (England), joined Aug 2007, 115 posts, RR: 0 Reply 8, posted (1 year 11 months 2 weeks 5 days 14 hours ago) and read 7854 times:
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 From United Kingdom, joined May 1999, 8274 posts, RR: 41 Reply 9, posted (1 year 11 months 2 weeks 5 days 11 hours ago) and read 7842 times:
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.
CptSpeaking From United States, joined Apr 2006, 607 posts, RR: 2 Reply 10, posted (1 year 11 months 2 weeks 4 days 10 hours ago) and read 7776 times:
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!! 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!!
Genius12 From United Kingdom (England), joined Aug 2007, 115 posts, RR: 0 Reply 11, posted (1 year 11 months 2 weeks 3 days 18 hours ago) and read 7742 times:
Mir From United States, joined Jan 2004, 13162 posts, RR: 65 Reply 12, posted (1 year 11 months 2 weeks 3 days 4 hours ago) and read 7715 times:
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.
UA772IAD From Australia, joined Jul 2004, 1424 posts, RR: 3 Reply 13, posted (1 year 11 months 2 weeks 3 days ago) and read 7710 times:
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!
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.
Genius12 From United Kingdom (England), joined Aug 2007, 115 posts, RR: 0 Reply 15, posted (1 year 11 months 2 weeks 1 day 17 hours ago) and read 7644 times:
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
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.
B727-200 From Australia, joined Nov 1999, 1049 posts, RR: 4 Reply 20, posted (1 year 11 months 1 week 5 days 11 hours ago) and read 7477 times:
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...
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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.
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