View Full Version : ILS Approach
01-03-2003, 05:27 AM
LAST EDITED ON Jan-03-03 AT 05:28AM (EST)[p]Can anyone help me? i have noticed that when I turn on the approach button on autopilot the aircraft does follow the ILS Approach but initially the aircraft turns to late to intercept the localiser and then has to correct itself. Does anyone have an explanition for this, a way to fix this would also be very helpful. Thanks
01-03-2003, 05:34 AM
You could try turning off the yaw damper or setting up the approach so that the ILS interception is from a shallower angle - about 30 degrees maximum, better still if it is 15 or less.
I have FSNavigator and use its waypoint function to create an imaginary waypoint on an extended centreline of the runway in use about 10-12 miles out. This gives the ILS time to sort itself out. I have also seen that often the ILS needle doesn't coincide until quite close to the runway - the crosswind component is adjusted for by the A/P but with a declining margin for error as the airport is approached which means the ILS is only finally met a short time before landing. Does yours sort itself out if you leave it?
01-03-2003, 05:42 AM
Yes the ILS sorts its self out, but only close to the runway, which doesnt leave much time to take over manually. You say if i turn the yaw damper off this might help the ILS intercept the localiser first time?
01-03-2003, 05:55 AM
I have just tried turning the yaw damper off and it hasnt made a difference, it couldnt be something to do with the aircraft.cfg could it?
01-03-2003, 06:53 AM
It is just a bug in FS. Like when the aircraft turns along its flightpath on autopilot, it turns on top of the point, not before like real jets do.
It has gotten better since FS 2000, but it still is not acurate. For instance, going into Frankfurt, Germany, for real, you are asked not to put your gear down and maintain better than 160 or 180 (I can't remember which) all the way to the outter marker. So, when you intercept the localizer before the outter marker, you are doing better than 180 knots. I have never seen a C-17 do what FS does by over shooting, pitching suddenly, and all that. Even sometimes at an intercept speed of like 220, and better than 30 degrees intercept angle.
Now, understand that a C-17's "APR buttons" and computers are a little more high-end compare to the programs written into FS. This is the case with most airplanes, even a lot of the GA aircraft out there.
Don't worry, Microsoft is getting there. To have planes and facilities that did EVERYTHING like it was supposed to, you would need a hard drive by itself just to hold the info.
SSgt. Adam Sereika
Flying Crew Chief - C17A Globemaster III
01-03-2003, 07:25 AM
Yes, that seems to be a prob in FS. I am using FS Navigator and I intercept the ILS at 30 degree or less angle. In FS NAV I push the APR switch and I intercept the localizer from around 15-20 miles off the runway. It goes quite off the localizer but eventually it intercepts it and the descent is also very accurate , it stays on the glideslope till I get to the runway . I turn in off around 500 feet off the runway and handfly the aircraft to the runway. U might wanna try FS Nav if u havent got it yet.........
01-03-2003, 07:57 AM
I´ve noticed that using the GPS NAV to follow a route. Yesterday I was travelling from PHNL to KSFO following a more or less direct route until KLAX and turning north. I went to do some business and let the A/P running the plane (at 16x speed). When I returned A/C was 1 nm from KLAX and following the route. It just started to turn when range was 0 nm and as such it overshot took the a/c some ten miles to "find" the northerly course again.
I am not a programmer but I think it shouldn´t be difficult to program the A/P to start turns say 1,5 nm from the waypoint.
Curitiba - Brazil
01-04-2003, 03:12 AM
I have noticed that the autopilot intercepting the localizer overshoots the "beam" because the bank angle is too shallow and it doesn't increase to keep up with the movement of the needle. Normally when movement of the needle is detected a standard rate turn should begin. Most often than not the rate is almost half-standard. To counter this, what I do is once vectored to the intercept course (about 30 degrees) I either
1. turn of the heading hold and make the turn until needle is centered and then turn on approach hold or
2. set the heading hold to approach course (the auto pilot makes a standard rate turn when you do this) and then set the apr hold or
3. hand fly the approach from that poin. (depends on weather, if IMC I let the AP fly the approach, if not then I request a visual approach.
01-04-2003, 02:45 PM
Another trick I picked up from someone's post:
When ATC assigns you to your final approach altitude, from which to intercept the localizer, set your altitude 100 feet LOWER than assigned. Somehow this seems to make it easier for the A/P to lock on.
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01-04-2003, 02:49 PM
You noticed that eh? It likes to nose the ILS.
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