by Michael J. “Mick” Kaufman
In between issues, I am always thinking about topics to write in my column for the next issue of Midwest Flyer Magazine. Some of our best topics come from our readers who are experiencing difficulties with something or have a question.
Last month I received a call from a pilot from Wisconsin Rapids, Wisconsin, which was related to his “autopilot.” I have also included in this issue a flight experience with a student from Viroqua, Wisconsin in his G-1000-equipped Cessna 182 Skylane.
I have written many articles about autopilots in previous issues, but it seems to continue to be of great interest among our readers. Why or how the name “George” became associated with autopilots is a mystery to me, but I continue to use this name when referencing autopilots.
If you were an aircraft or avionics technician and a pilot asked you to design and build an autopilot for your airplane, you would surely laugh at them and say “there is no way we could get such an approval from the FAA.” But one of my dear friends and colleagues did just that… Bill Hale of Ft. Collins, Colorado designed his own autopilot and received FAA approval for its installation in his Bonanza after meeting all of their requirements. Bill is now retired as an electrical engineer from Hewlett Packard, but now works as an instructor with the Bonanza Baron Pilot Training Program (BPT) and is an engineer consultant on Avidyne’s new autopilot, which I understand is one of the best new generation autopilots on the market, today. Bill is also someone who I often call upon with difficult autopilot questions.
So why did “George” do this or that is the question from many of our readers. To answer this question, we need to understand that the autopilot needs to be able to do all of our legacy approaches like the ILS, LOC and VOR approaches, as well as the newly designed and certified RNAV/GPS approaches. Having trained hundreds of pilots for their instrument ratings over the past 45 years, I have seen how simple our new avionics systems have made certain procedures, and I think this is the reason why some of the newly rated instrument pilots do not understand how some of these legacy systems work. The sad thing about this is that instructors – including myself – fail to teach the old ways of doing things, as it may be a waste of time, effort and money.
The ILS (Instrument Landing System), for example, does not send out just one localizer or glide-slope signal, but rather many signals. Radio transmitters and antennas cannot be programmed to send just one course line, at least with today’s technology, and this is depicted in the Airman’s Information Manual (AIM 1-1-9 (b) (6)) (Fig. 1-1-6). These false courses or harmonics exist, and we as pilots need to be able to recognize and avoid these courses.
Autopilots need safety features to avoid situations, which could become disastrous.
When teaching the ILS approach many years ago before the advent of LORAN (Long Range Navigation) and GPS (Global Positioning System) navigation, I would trick an instrument student into trying to follow one of these false courses. To fully understand how these false courses can confuse the pilot and the autopilot, a pilot flying a heading to intercept the localizer course to track it outbound for a procedure turn or inbound and sees his CDI (Course Deviation Indicator) come off the peg and center, will immediately turn to the depicted heading only to find that the CDI makes no sense, and the signal that created the movement, disappears. If flying the autopilot on NAV (Navigation) or APP (Approach) mode, it becomes obvious after a short time, the signal has disappeared, and there is no course to navigate. For pilots flying these legacy approaches today without GPS intercept guidance, there are some guidelines to follow.
If being vectored by Air Traffic Control (ATC) for an intercept, follow the headings given by ATC to intercept and ignore those CDI fluctuations on ILS and localizer approaches. If navigating on your own for intercept without a GPS, there needs to be a secondary indication that you are on the correct course. This could be an ADF (Automatic Direction Finder), DME (Distance Measuring Equipment) Fix or MB (Marker Beacon). Many approaches may note that ADF, DME or radar is required to execute this specific approach (FIG 1); GPS may be substituted for an ADF or DME per regulations and is not noted on the chart.
Having explored the false localizer courses, let’s look at false glide-slopes.
We can see that the lowest glide-slope angle is the one that George or the pilot must fly. This is usually about a 3-degree angle, and the false glide-slopes are way too steep for a normal approach descent (AIM 1-1-9 (d) (4) *. As a safety feature to prevent autopilots from intercepting these false glide-slopes, there is a timing circuit in the autopilot. Each specific make and model of autopilot is a bit different as to the amount of time required and when the timing begins. Here is an example for the purpose of this article.
Let’s assume that the localizer needle starts to move off the stop as you are being vectored for the approach, then the timer begins and is set to 40 seconds by design. The glide-slope centers before the preset time has expired, and the autopilot will not capture the glide-slope. This would mean that we were vectored too high or too tight for the autopilot to verify that this is the correct glide-slope for the approach. In many cases when ATC vectors an aircraft in too tight, there is no glide-slope capture with the autopilot. The Air Traffic Controllers’ Handbook (ATCH 5-9-1)** specifies that they must vector aircraft more than 2 miles outside the FAF (Final Approach Fix) or an approach gate (see below)**, or they must confirm with the pilot that he/she will accept the tight vector, and the final turn should be within 30 degrees of the inbound course. For conclusion on this subject, when setting up a course direct to a FAF, you can assume that the glide-slope would not capture on the autopilot due to the timing circuit on the autopilot.
There are so many new features in our modern avionics, and it is difficult, if not impossible, for a flight instructor to know all of them.
Several years ago, I went to school at Flight Safety for the G1000 system in the new Beechcraft Bonanza and Baron. The training curve is quite steep as they covered every function of the system. A lot of this goes back to a term that I have used previously called “buttonology,” (which button do I push and when). From an instructor’s point of view, I do not teach every conceivable function of these complex devices from the start. Rather, I teach and review them numerous times before going on to the next function.
In a recent flight with a student in his gorgeous new Cessna 182 with a G-1000/GFC-700 autopilot, I decided to teach him profile descents on the autopilot. When a flight plan is programmed in the G1000 and you load and activate an approach, the G-1000 box figures out where you need to begin your descent to arrive at the altitudes shown on the approach or transition. A dot appears on the Multi-Function Display (MFD) that is labeled TOD (Top of Descent). One minute before reaching the TOD, a synthesized voice from the autopilot announces “vertical track.” The pilot must now verify that he/she wants this to happen by pressing the “V-NAV” button on the autopilot. After pressing this button, the pilot must set in the lowest altitude that the aircraft can descend to before making a decision to land or go missed.
We tried this several times in the Cessna 182, and I got egg all over my face. It required a call to a colleague to find out what we did wrong. What we had forgotten was setting the minimum descent altitude (MDA).
Another great feature incorporated into the G1000 system is that each profile and level off altitude is displayed on the MFD and can be edited should ATC give you a different altitude on a specific segment. These new nav systems are really great, but require a lot of training to get current and stay proficient and for that reason, I do not recommend installing one in your aircraft if you only fly 20 hours a year. For my student who flies regularly for business almost exclusively, this is a great aircraft and avionics package.
I am confident we will find some more interesting subjects to cover on instrument flying in the next issue of Midwest Flyer Magazine, so keep your emails and phone calls coming!
4. Pilots must be alert when approaching the glidepath interception. False courses and reverse sensing will occur at angles considerably greater than the published path.
**ATCH 591. VECTORS TO FINAL APPROACH COURSE
Except as provided in para 7_4_2, Vectors for Visual Approach, vector arriving aircraft to intercept the final approach course:
a. At least 2 miles outside the approach gate unless one of the following exists:
1. When the reported ceiling is at least 500 feet above the MVA/MIA and the visibility is at least 3 miles (report may be a PIREP if no weather is reported for the airport), aircraft may be vectored to intercept the final approach course closer than 2 miles outside the approach gate, but no closer than the approach gate.
2. If specifically requested by the pilot, aircraft may be vectored to intercept the final approach course inside the approach gate, but no closer than the final approach fix. EXCEPTION. Conditions 1 and 2 above do not apply to RNAV aircraft being vectored for a GPS or RNAV approach.
b. Provide a minimum of 1,000 feet vertical separation between aircraft on opposite base legs unless another form of approved separation is established during turn-on to final approach.
c. For a precision approach, at an altitude not above the glideslope/glidepath or below the minimum glideslope intercept altitude specified on the approach procedure chart.
d. For a non-precision approach, at an altitude which will allow descent in accordance with the published procedure.
EDITOR’S NOTE: Michael J. “Mick” Kaufman is a Certified Instrument Flight Instructor (CFII) and the program manager of flight operations with the “Bonanza/Baron Pilot Training” organization. Kaufman conducts pilot clinics and specialized instruction throughout the U.S. in a variety of aircraft, which are equipped with a variety of avionics, although he is based in Lone Rock (KLNR) and Eagle River (KEGV), Wisconsin. Kaufman was named “FAA’s Safety Team Representative of the Year” for Wisconsin in 2008. Email questions to email@example.com or call 817-988-0174.