ILS Freq

[bradgib]

Hi everybody! My biggest problem in FS is landing. Correct me if I'm wrong, but I think ILS Freq lands the plane for you. If so, how do you use it?

Thanks! -bradgib

[mdklatt]

[font size="1" color="#FF0000"]LAST EDITED ON Jan-24-03 AT 10:49PM (EST)[/font][p]>Hi everybody! My biggest problem in
>FS is landing. Correct me
>if I'm wrong, but I
>think ILS Freq lands the
>plane for you. If so,
>how do you use it?
>

Consider yourself corrected. :-) First of all, you've got to get the terminology straight. ILS stands for Instrument Landing System. This is a pair of transmitters at the runway. Instruments in the cockpit display the ILS signals so that you can follow them to the runway. A frequency, of course, is just what you enter into the NAV radio to receive ILS signals. The ILS will not land the plane for you. The AP in the default FS planes is capable of flying an ILS approach (with varying degrees of success), but you should disconnect it at a few hundred feet and complete the landing manually. Actually, you should be able to fly the entire approach by hand at least once and awhile. You are the pilot, not a passenger. I highly suggest you start out at the beginning. Take all the lessons included with FS and read all of the reference material.

What you are talking about is autoland, which requires special ILS equipment at the runway, special equipment in the plane, and special pilot certification. To use autoland in FS you just need to find an addon panel/plane that has that capability.

[av84fun]

Just to add a bit to the above excellent post, the two ILS signals referred to are the Localizer and the Glideslope. The localizer "beam" defines the extended centerline of the runway so that by the deflection of the vertical needle on the instrument panel guage (a VOR head or HSI)you can determine if you are to the left, the right or on the runway centerline.

The glideslope is a little more difficult to grasp. It's beam tells you if you are above or below a slant angle that will lead you to the touchdown zone AT THE SPEED YOU ARE TRAVELING. In other words, if you are on a 4 degree downward slant, you might be on the glideslope at 90 knots but might trend above it at 120 knots. That is because at faster/slower speeds you move more or less over the ground and will arrive in the neighborhood of the touchdown zone sooner or later. Does that make any sense??? I hope so.

The major issue with the glideslope is that in NARROWS as you get closer to the TDZ. Imaging a cone with the point at the TDZ and the open portion tilted upwards. With that image, you can understand that as you get closer to the TDZ, smaller and smaller corrections in pitch/speed are required to keep you inside the cone and the opposite is true the farther out you are which confuses lots of pilots both simmers and in the real world.

The confusion stems from the fact that if you trend above or below the GS, say 6 miles out, you must make a relatively significant correction to get the horizontal needle to center.

But at 1 mile, the SAME needle deflection will cause a MAJOR displacement of the needle causing many pilots to begin "chasing" the GS..in effect, doing vertical "S Truns" above and below...but by using the SAME control inputs that worked fine farther out.

So, the closer in you get, dont' forget to use SMALLER AND SMALLER control inputs to correct any deviations from the GS path.

If you really want to get "professional" you can sort of "calibrate" your control settings for power, flaps and descent angle so that you can practically fly the glideslope hands off...not actuall hands off but with VERY few control inputs...absent large variations in wind speed and therefore, ground speed.

It takes a while to figure out but use the A/P to help get it nailed. Get, say, 10 miles out, capture the Localizer and let the A/P fly it in the NAV Mode. Select one notch of flaps and apply whatever power setting will equal the recommended approach speed for the aircraft you are flying. Make notes about what power setting and deck angle (on the artificial horizon) correlate with having achieved the correct approach speed.

If it is, say 20 inches of MP and a + 3 degree deck angle to achieve 90 knots with one notch of flaps, then when you need to adapt to approach speed, just set those values up and the airplane will fly level at 90 knots every time.

Then just as the glideslope is captured (centered needle)select another notch of flaps drop the gear and select the Approach Mode on the AP so it will couple to the full ILS. Then just reduce power slowly until your standard final approach speed is achieved. The AP will handle the deck angle for you. It takes a while to get stabilized and you may have to shoot a few approaches before you get things all settled down but with a little patience and with the help of the AP, you will eventually get set up with the proper power setting and deck angle to fly a typical glideslope at the exact speed you desire every time...within reason.

In a light single RG, a typical final approach set up might be something like, 2 notches of flap, 18 inches of MP, gear down,
- 4 degrees of deck angle and 80 knots. Whatever the values are, write them down and you will get very nearly the same results every time with minor variations in power depending on the headwind component.

If you do the above, you will have a MUCH easier time hand flying a stabilized approach.

Hope I didn't leave out too much. Others will correct any mistakes...it's late here!!
Enjoy

[rsdyrda]

[font size="1" color="#FF0000"]LAST EDITED ON Jan-25-03 AT 11:29PM (EST)[/font][p][font size="1" color="#FF0000"]LAST EDITED ON Jan-25-03 AT 11:28 PM (EST)[/font]

FYI...a little "rule of thumb" I use.

To fly a 3deg descent (the typical angle in an ILS) take your GROUNDspeed times 5 and pitch for that in the VSI. EG using the 90kt groundspeed mentioned above, pitch for a 450'pm descent.

The main reason people "snake" localizers and glide slopes is that they focus on the VOR/OBS or HSI for too long. The DG should still be primary for tracking the localizer and the VSI is primary for pitch. The needles are there for reference only. If you fly the needles too much you will typically fall off the closer you come to the runway.

Final approach fix inbound (typically glide slope intercept for an ILS), all turns should be made at a 1/2 std rate or less (or a min of 5deg a time on the DG). If you do not know what a std rate turn is, it is the markings on the turn coordinator. If your flying a jet/etc with no turn coordinator you can estimate the bank angle by taking Airspeed/10 and add 5deg or just limit yourself to no more than 5/10deg.

As for clean or dirty (flaps/gear). Most complex/high performance airplanes use flaps during the approach with the gear coming down a dot above GS intercept. A 172 will use no flaps on the approach. For example using the Project Fokker 100, I use flaps 5/15 getting established on the approach, at GS intercept use flaps 25 and gear down, at middle marker or dme 1.0 use full flaps.

Hope this helps

[bradgib]

Thanks all for your help! think I got a better idea now! God, was I way off.

Thanks, bradgib

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