ILS APPROACHES

[johnyyz1]

i need help. when i try to do a ils approach using autopilot i
- tune the ils frequency
- turn on autopilot using nav mode/and apprch mode
- set the asi mode

it will lock onto the localizer properly BUT does not follow the glideslope, and i can't get it to keep a preset airspeed.
i always crash SHORT never long of the runway.

WHAT AM I DOING WRONG ? If there are any REAL pilots out there who know PLEASE HELP !!!!

THANKS , JOHN

[ssteiner]

I generally find that in order to successfully intercept the glideslope in 2002 you need to "come at it" from below. In other words, when your glideslope indicator comes on, and as you lineup with and approach the runway, the glideslope indicator should be high (or at the top). As you probably know, this is the indicators way of telling you to go "UP" to intercept. However, as you approach the runway, you will notice it start to come down, since you're getting closer. When I fly, the glideslope usually won't intercept with the autopilot until at least the outer marker indicator (which is indicated by the blue "O" light on your panel), and is usually 7-10 miles out.

If you haven't intercepted, continue to reduce your altitude by inputting the altitude you want on the autopilot "alt" control. Under no circumstances should you ever program the altitude to the actual altitude of the airport. I rarely have to go below 2000 agl, but if you do, never go below the DH, for obvious reasons - you don't want (or at least I don't want) the autopilot flying me into the ground if I can't see the runway for a least a few moments before landing. Anyway, in the event that the glideslope is not intercepting, simply set an altitude and set your VS indicator on the autopilot to 700 fpm. Doing that effectively mimics the autopilot's interception of the glideslope, though it will require more babysitting during final approach. Good luck!

[av84fun]

ssteiner...All excellent advice. However
"simply set an altitude and set your VS indicator on the autopilot to 700 fpm. Doing that effectively mimics the autopilot's interception of the glideslope,"

The ground speed (and therefore the type of airplane being flow) has a major affect on the descent angle necessary to fly the glideslope. At faster speeds, because you are covering more ground for a given unit of time, you need a steeper glide angle and vise versa. In light singles with +/- 75kt approach speeds (zero wind) 400-500 fpm usually works. there is a formula to calculate it that I have forgotten and never found to work very well when I did know it because approach ground speeds are so variable as you descend through changing layers of wind.
Regards

[ssteiner]

Very true. I instinctively offered advice appertaining to the airplane I fly most often in 2002, the Baron. But it's true, in an aircraft that's flying slower, descending at 700 fpm will drop you too fast, because it takes longer to get to the runway. The reverse is of course true with larger airplanes. Perhaps a good way to learn the best descent rate is to apply that descent rate that maintains the glideslope indicator in the middle position for the entirety of the approach. Once done, you would thereafter know the appropriate descent rate for each particular airplane.

-Scott

[Whiteman]

Have a look at the "Flying the FS2K2 autopilot" in the "Pilot Instrction" section of the FS2002 Tips Library (banner link at the top of the page).

It's a full step by step tutorial and is well worth a look.

John

http://www.flightsim.com/dcforum/Use...e45a5fb8a6.gif

http://flightsimvetclub.tripod.com/

[Silverblade]

Make certain your altitude hold is off.

Silverblade

http://www.flightsim.com/dcforum/Use...6b3fd541d6.jpg

[artburke]

Au contraire, Pierre. If you look at the autopilot during an approach, you can typically see the following functions set:

AUTOPILOT - ON
ALTITUDE - HOLD
HEADING - HOLD
APPROACH - ON

As pointed out above, you will typically intercept the ILS from below the glideslope. When the localizer signal "locks on" to your aircraft, the heading indicator will no longer be illuminated. When the glideslope intercept occurs, the altitude hold will no longer be illuminated either. At that point, the altitude hold function goes off automatically.

If you turn off the altitude hold *before* glideslope intercept there ain't gonnna be nobody looking after your altitude!

One last point - many, many simmers fail to realize the ILS (and the autopilot) have zilch to do with the speed control. If the plane you're flying has any form of speed control, the throttle must be armed and the speed is controlled externally (in relation to) from the autopilot.

Art

[Cactus521]

One bit of advice to add is to watch the speed. I prefer to intercept the G/S around 10-12 miles out. Generally, as soon as I intercept the G/S I'll back off on the throttle to keep my speed steady. Then I'll gradually reduce speed until I'm at my desired final approach speed. One thing to avoid is letting the speed creep up... The aircraft will have a tendency to rise above the G/S, and at a certain point the lock will "disengage". I've noticed the G/S lock is more tolerant of deviation below the G/S than above it.

Procedures vary with different aircraft as well. I enjoy slewing to around 15-20 miles out and practicing FS2002 ILS approaches in the different A/C I fly. I've probably done several hundred this way, and have gotten to the point where they work, every time. FS2002 G/S lock is less tolerant than FS2000 (some say it is also more realistic). In spite of this, following these tips and the others posted here will make ILS approaches just as reliable, with the exception of those rare airports where the ILS is offset either intentionally or by error.

John
KPHX