I've received a number of email questions regarding my post on ILS approaches in FS2000 and making them more in line with "real" IFR procedures. Since the subject seems to be of general interest, I'll post it here rather than privately. Parts of the following are excerpts from the ILS lessons at the IVPA Virtual Training Academy - http://www.ivpa.com/vta/ Many of the questions concerned using the APP function of the Auto Pilot for approaches. In order to explain that, we first need to talk a little about approaches and how you fly them by hand. Which, by the way is the way I prefer to fly. I figure the point of flight simming is to fly, not be a passenger. The best thing you can do for increasing the realism is to do a little study and invest in some charts and approach plates. The various sources for these are a frequent topic in the newsgroups, so I won't repeat that here. Without the plates, a lot of guess work is involved in shooting the approach since you don't have the advantage of knowing the fixes and procedures for the published approach. The segments and procedures for an approach are discussed in the lessons mentioned above. Most ILS approaches will have a glideslope angle of 3 degrees. This means that for each nautical mile from the airport, you should have 300 feet of altitude. An ILS approach will typically have an initial altitude at the outer marker of 2000 - 4000 feet. From this, if you know where the outer marker is and its distance from the airport, you can get a pretty good estimate of the altitude for making a procedure turn or intercepting the localizer. Your descent should not start until you cross the OM inbound. Before reaching the OM, you should have already done your approach checklist and have the aircraft at approach speed and configuration. Otherwise, you're going to be really busy at the OM and may get to learn about missed approaches. On crossing the OM, lower your gear, increase flaps in accordance with the procedures for the aircraft you are flying. If you are at the correct altitude, when you cross the OM you should intercept the glideslope almost immediately. When the glideslope centers, start your descent. The rate of decent required to maintain the glidepath is determined by the glideslope angle and your ground speed. If you assume the 3 degree standard glideslope, you will usually be pretty close. That only leaves the speed as an unknown. On the approach plates, there is a table which shows the correct rate of descent for several ground speeds. If you don't have the plates, look at one of the ones in the FS2000 manual since these are constants. For example, you will find that at 90 knots you need a 487 fpm descent. On an approach, power (your throttle) determines airspeed and pitch (forward or back pressure on the stick or yoke) determines rate of descent. You need to experiment with the different pitch and power settings for your particular aircraft so that you can quickly setup a descent at a given rate. Each combination of pitch and power should produce the same results every time. What does all of this mean? It means you have a lot of work to do on an ILS approach. The key to a smooth approach is gentle corrections. If you use a lot of turn, bank, throttle, or pitch changes, you will end up chasing the needles and have a rough ride. The nearer you get to the runway, the less the amount of correction needed. Once on the localizer and glidepath, if you are getting low, increase power a little, if you are high, decrease power. If you need to speed up, increase pitch or to slow down decrease pitch. If you are able to maintain the correct speed and rate of descent, you are going to be lined up to land precisely on the touchdown zone markers (two sets of three parallel white stripes 500' from the threshold). At the DH (Decision Height), which is usually 200' above the touchdown point, you make the decision as to whether you can continue the approach or initiate a missed approach. If you have the runway environment in sight, you may continue and land. Runway environment is FAA speak for anthing connected with the runway. It could be the approach lighting system, a VASI, the threshold, etc. Once you have the runway in sight, don't "dive for the numbers". That is not your goal on an ILS. You might get away with it in the Cessna 182, but in the B777 your landing gear are way below you and may trim the trees at the end of the runway if you go below the glidepath. Your goal is to hit the touchdown zone. There is an aiming point included on runways that have a precision approach. This is the two white rectangles 1000' from the threshold. If the aiming point in staying steady in your wind screen, you are headed directly for it. If it is moving up, you are low, if it is moving down, you are high. Category II and III approaches are ILS approaches with lower minimums in the real world and require more sophisticated equipment than a standard approach. I have not experimented with the modeling of these in FS2000, so I am not sure how well the auto pilot will do if you try to use it all the way down. The last topic I'll cover in this one, since it is getting a little long is when to cut the throttle. This depends somewhat on the aircraft. For anything up to and including the King Air, you should be able to reduce your throttle to idle power when you cross the threshold. In the larger props and jets, the reduction is less, (or non-existent) until actual touchdown and the amount of flare is very small. In other words, you fly it onto the runway. The lessons included in FS2000 Pro (in the manual and the flight lessons) are very good and will give you some practice with your "instructor" along to help. Next time I'll cover using the auto pilot for a coupled approach. Ray -- *~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~* | Ray F. Jones (SATCO2) - SATCO Deputy Director, IVPA Exec. Director | SATCO International HQ http://www.satco.org/ | IVPA http://www.ivpa.com/ *~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*