Flying With Accurate Flight Instruments

by Michael J. “Mick” Kaufman

In this issue of Midwest Flyer Magazine, I will be addressing the issue of “aircraft instruments” and their importance in making a safe and accurate IFR flight. I would also like to show how an aircraft with poorly performing instruments, coupled with bad aeronautical decision-making, contributed to a fatal aircraft accident.

In the many years of helping pilots get an instrument rating and stay safe and current on instruments, I have put much emphasis on having good equipment in the aircraft. There are certain acceptable standards of performance for our aircraft instruments, some set by the Federal Aviation Administration and others recommended by industry.

Our transponder, altimeter, pitot static system and mode C encoder must be checked, certified and signed off every 24 calendar months. For instance, Federal Aviation Regulation (FAR) 91.411 has set the operating standard for altimeters used for IFR flight as having a maximum error of 75 feet. When aircraft are advertised for sale, a common description in the ad is that the aircraft is certified IFR.

How about the gyros; what is acceptable for IFR flight?

An industry accepted precession for a heading indicator is 3 degrees in 15 minutes, which I find a large percentage of heading indicators do not meet.

One of the first steps I take with a new instrument student is to find out what works in his airplane and what does not work. This gives us a chance to get it corrected early in training and if a repair or replacement is necessary, we are not in a rush with a flight check a few days away. Many of the newer aircraft have glass panels or a slaved horizontal situation indicator (HSI) or heading indicator that rarely poses any problems, but the older non-slaved units do.

My first test is to set the heading indicator to runway heading prior to take-off, fly for an hour and land on the same runway and see how much precession (drift) that the instrument has. If it is excessive, it should be replaced. The problem is the replacement unit is often no better than the unit it replaced. Your best solution is to install a “slaved compass system” or an HSI. This was one of the best decisions I made when updating my Bonanza about 20 years ago, which had an old flat-faced A&N directional gyro. The cost for a used Century slaved heading indicator with a bootstrap at that time was about $700 installed…same as a new non-slaved unit. If you looked at this same system today on the used market, the price seems to start at around $250.00 with one advertised near 6AMUs $6,000.00 (the seller is dreaming). With so much older outdated equipment around, there are a lot of choices, but your installer will wonder why you do not install a state-of-the-art glass panel, as the installation cost on some of the older equipment would be money poorly spent.

You may have noticed in my above statement that I indicated to set your heading indicator to runway heading and not the magnetic compass. The magnetic compass is another instrument installed in our aircraft that is in many cases so far off, it is a joke. We are required to have a compass correction card in the aircraft per FARs, but with all of the electronics in modern aircraft, turning on one switch may cause a compass change of 30 degrees or more. Setting the heading indicator to the runway heading helps prevent this, at least initially. Runways are marked to the nearest 10 degrees magnetic, so the largest error we could encounter would be 5 degrees. If you have an accurate magnetic compass, you are in the lucky minority. If you have an accurate vertical card compass, you are truly blessed, as they work great.

Several years ago while I was presenting safety seminars for the FAA Wings Program as part of the FAA Safety Team (FAAST), I developed a presentation that I titled “Hold My Beer and Watch This.” The content and purpose of this presentation was to place emphasis on Aviation Decision Making (ADM), bringing out the five hazardous thought patterns that affect us not only as pilots, but in our everyday lives. The reason this became part of my column this month was influenced by a fatal accident involving a Mooney aircraft making an ILS approach to the Norfolk, Virginia airport (KORF).

I can relate to poor ADM myself for making an icy night approach in my Bonanza to my home airport, Tri-County Regional, Lone Rock, Wis. (KLNR), in a snowstorm when returning from El Salvador with a fellow pilot. The weather 30 miles away in Madison, Wisconsin was clear.

When I use information on an accident or incident as part of my column, I would like to again emphasize that this is for educational purposes only and not a Monday morning quarterback critique. The other reason for including this accident was that there was a heading indicator or directional gyro (DG) that played a major role in this accident.

The pilot of Mooney NXXXXX decided to depart Key West, Florida (KEYW) at 8:30 p.m. EST for a night IFR flight to his home airport of Suffolk Executive Airport in Virginia (KSFQ). The pilot made a planned fuel stop at the Palatka Airport in Florida (28J) and departed the final leg home at 11:57 p.m. The pilot planned for a 3.5-hour leg to his home airport, according to his flight plan, and the fuel on board showed 5.0 hours. The airplane was borrowed from a friend and there is no indication of how much this pilot had previously flown this airplane. We do know, however, that he had flown it to Key West, Florida several days prior.

After arriving at KSFQ, the pilot attempted to make an RNAV GPS 22 approach to the airport that was reported at or below minimums for the approach. Upon missing the approach at Suffolk, the pilot elected to fly the ILS 23 approach to Norfolk (KORF), which he missed the first time and crashed 2300 feet northwest of and abeam of the Runway 23 threshold on his second and fatal attempt.

There are several noteworthy items that were provided to me by a local Norfolk pilot, which I would like to note here with some of my own comments:

Upon being vectored to the Initial Approach Fix (IAF) for the RNAV GPS 22 into KSFQ, the pilot overshot the final to the southeast, and was given a heading to re-intercept. The pilot then said something to the effect of having a problem with his GPS approach plates. Whether that meant a problem programming his avionics or a problem bringing the plate up in whatever tablet device he was using (if he was using one) is unknown. In the event he was using paper, it could have been a problem finding the plate as he was bouncing around in turbulence.

The pilot made comments about his directional gyro precessing pretty bad while on his approaches into KORF and ended up using no-gyro vectors on his last and final approach.

Early on, the pilot reported his fuel quantity as about an hour and a half remaining. He would later correct this to actually having about a half-hour of fuel remaining.

A previous aircraft landing on Runway 23 at KORF had reported the localizer needle jumping around. Air traffic control said that he was the first one to report it, out of several aircraft. The mishap pilot was next on the approach and also reported a “flickering localizer needle.” Although I doubt this was a factor, it was interesting, nonetheless.

After reviewing the above information, many of you would wonder why a pilot would decide to depart late at night into questionable weather in an aircraft that he should have known had some questionable equipment. Apparently poor fuel planning was involved as well. The first one of the hazardous thought patterns that came to my mind as defined by the FAA’s publication is as follows:

INVULNERABILITY: This thought pattern is perhaps the most dangerous. This individual thinks, It wont happen to me. After encountering unexpected headwinds, this pilot flies past a good fuel stop because things always work out.

In future issues of Midwest Flyer Magazine, I will elaborate on this and four other hazardous thought patterns.

The issue of dealing with a precessing gyro is not easy to overcome, but I have some suggestions. As previously noted, I do not recommend resetting the heading indicator to the magnetic compass, as errors can be significant.

I flew an aircraft earlier today that had a magnetic compass perfect on a west heading and off 30 degrees on an east heading. When faced with this gyro situation, I recommend setting the heading indicator to the track information displayed on a GPS. The track information displayed on the GPS has wind factored in, which can be helpful; however, the pilot must remember to reset the gyro when turning more than 30 degrees due to a change in the wind correction angle. If the pilot involved in the fatal crash described here would have used this method and was capable of hand flying an approach, the flight may have had a better outcome.

Additionally, in extreme crosswinds on approaches, many autopilots will not work and may show this limitation in the autopilot supplement of the Pilot’s Operating Handbook. Good aeronautical decision-making, having knowledge of your aircraft systems, and being able to hand fly an approach when the autopilot cannot, is essential.

Keep your instrument flying skills sharp, and exercise good aeronautical decision-making, so you may enjoy the next issue of Midwest Flyer Magazine.

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 captmick@me.com or call 817-988-0174.

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