Need to Know ILS Things:
1. Know the dimensions of the localizer course.
2. Intercept and descend on localizer before reaching the marker.
3. Set power and trim for stabilized approach airspeed.
4. Keep track of where you are and what to expect.
5. Have the needed numbers before you need them.
Cockpit Requirements
--Set the radios
--What you hear...not what you expect
--Familiarity with region
--Know point to point distances and times
--Organized copy sequence
Use All Your Navaids
1. ADF needle on frequency and pointed to marker.
2. Set and verify frequencies
3. Check for flags
4. Move with the marker to find primary heading.
5. Write and use your pitch and power transition settings.
At the Marker
1. Be prepared before you get there.
2. Write, know and set the numbers. Verify.
3. Inside the marker you just listen to ATC.
4. Maintain orientation and situational awareness
Middle marker (amber)
A point on the ILS glide slope Final altimeter check. MM should be part of briefing. The middle marker is 1/2 (3500 feet) mile from runway at decision height which is typically 200' AGL above TDZ. MM inoperative does not change minimums as of 1993. Check the marker crossing altitude as an altimeter check. The middle marker is not a required component for full ILS minimums nor the localizer
ILS Specifics
1. One mile out one degree is 100' or one dot. 200' equals 200'.
2. ATP standards are one dot deflection calls for a missed approach.
3. If you have not stabilized your descent you will lose the localizer as well.
4. Pitch to an airspeed and power for descent rate.
5. Inside the marker pitch to glide slope and rudder for localizer.
6. Know the pitch-airspeed-trim setting for the glide slope.
7. Localizer sensitivity is 2.5 degrees from center to side.
8. If localizer needle waves, change propeller rpm.
The ILS has two fixed beams , the localizer provides left/right orientation and the glide slope provides vertical slope. However there are several glide slopes, only one of which is correct and verified at the final approach fix by the altimeter check. The false glide slopes provide a very steep approach which may be difficult for slick aircraft to follow. By the time you recognize the problem the missed is the only option. By keeping the localizer and glide slope indicators centered you will be flown right to the end of the runway. This can be done by the pilot or by the flight director. The ILS problem is that only one aircraft can use the ILS at a time or about 20 per hour.
Cat 1 ILS at DH requires:
1. See runway environment
2. Continuously able to make normal descent to landing
3. Required flight visibility.
About the ILS
Until the GPS WAAS system is perfected, nothing gets you closer to the runway than the ILS. The lateral and vertical guidance will fly you into a blackboard-sized space called the decision height or (DH). The DH is the missed approach point. You either see the runway or you go missed.
The components of the ILS are a localizer, markers and glide slope. The localizer is an antenna that sends a beam along the runway centerline out some 18 miles and up to 4500 feet. It also sends a signal out backwards called the back course. Depending on your equipment you will always fly to the needle to center it. The difficulty of a back course is that you will not have a glide slope and may need to fly away from the needle to keep it centered. This reverse sensing is also true if flying outbound on the localizer. The localizer's full deflection is 350' to each side of the center line at the runway threshold this full deflection is only 2.5 degrees wide to each side. The OBS has no effect as it does with a VOR. The pilot is well advised to set the OBS to the runway direction the approach. On the missed immediately set the OBS to the VOR intercept that is usually a part of the missed. Be ready to change the frequency. Having a heading bug to set in the course or possibly the wind direction will give an added assist.
The glide slope is offset from the runway and sends a signal that is fifty-feet above the runway initially and slopes up on the true glide path to 1400' AGL near the outer marker. At ten miles out a full-deflected glide slope is 1500 feet off the center. At the threshold the full deflection will be close to five-feet. At the middle marker it is 200'. The glide slope is 1.4 degrees to full- high or full-low deflection.
Marker beacons are disappearing to be replaced by radar or intersection fixes. The middle marker is no longer required. Still remaining are the false glide slopes waiting for aircraft to be vectored into harms way. Only the outer marker remains to show the pilot the point on which to measure his altimeter setting accuracy.
Part 4 the Middle marker (amber)
A point on the ILS glide slope Final altimeter check. MM should be part of briefing. The middle marker is 1/2 (3500 feet) mile from runway at decision height which is typically 200' AGL above TDZ. MM inoperative does not change minimums as of 1993. Check the marker crossing altitude as an altimeter check.
A localizer has a four-letter code beginning with I to verify the localizer frequency. Failure to identify the code is a checkride bust waiting to happen. The Category I ILS has 200 -foot minimums while requiring 1/2 mile visibility. Larger airports with RVR reading and runway lights have different visibility minimums.
Flying the ILS requires gentleness and accuracy of control movement. One technique I advocate is the use of yoke for altitude and decent control and rudder for heading changes. Airspeed is set with power. Airspeed can be set best by the use of pre-determined power settings.
Flying the ILS
The basic skill required of all instrument approaches is that of fly headings and altitudes. If this basic skill has a deficiency then the pilot will be overwhelmed by the additional details required of by the approach. Because of the funnel like increase in required flying precision of the ILS, the pilot must sense the changing sensitivity control requirements as the approach proceeds. The winds of change are a part of flying the ILS. My particular hometown LDA approach has more unusual wind directions and velocities than anyone would normally expect. Just two days ago I has occasion to have a student track the localizer with 90-degree 40-knot winds directly from the right up until we reached the outer marker. The wind changed from the right at only 20 knots inside the marker and at the runway gusts were 20 knots right down the runway. Keeping the needle even close was a composite of luck and skill.
Speaking of winds, a tailwind, decreasing headwind, light and variable wind, or no wind at some point on the approach will play havoc with your ability to time the approach, providing you remembers to start the timer. The vertical speed required to fly the approach is based upon ground speed. Your ground speed can be/will be just as variable as the wind. Accuracy is a crapshoot. Use the projected rate of descent given on the ILS chart for the ground speed you hope to maintain. A DME is a BIG help in adjusting your ground speed. My suggestion is that for a localizer type approach you select a vertical descent that will get you to the MDA about one minute before the projected time to the MDA runs out. MDA's time runs out at the runway threshold and makes the required normal landing unlikely. By moving it up a minute on the approach it at least gives you a shot at normalcy. The vanishing Visual Descent Point used to do this.
A major instructional problem is accomplishing desirable instructional ends without undue exposure to hazards. IFR actual with turbulence is such a problem. The peril of such a situation is loss of control with a resulting high speed and ultimate destruction of the aircraft. The same conditions could result in loss of control due to low speed. What needs to be taught in IFR turbulence is the maintenance of control because once lost, the control is exceptionally difficult to recover. Successful flight in IFR turbulence is a matter of personal discipline and attention to holding attitude and heading rather than altitude.
It is vital that the instrument student learn the judgmental decisions that make an approach possible. The student must be exposed to the lethal elements of any approach, distraction, below visual minimums and runway requirements. The training program should demonstrate the thought processes required to make both the 'make the approach' decision, and the 'make the missed' decision. A training program that makes every approach successful is not preparing the student for the real world of IFR flying.
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