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Wednesday, March 1, 2006

Tech Talk

Shawn Coyle

Why Use the Autopilot?

I'm surprised to have to write this article at all.

My flight instructors used to tell me I was definitely a minimum-skill- level kind of guy, and it took me a long time to get the hang of instrument flying. So when the opportunity to use an autopilot to make life easier came along, I was delighted and used it even when VFR. It just made things easier, and the more I used it, the more I like it.

Imagine how surprised I was to find that not all helicopter pilots share this enthusiasm. Some, it seems, even actively resist using the autopilot.

I first heard this in a speech at a helicopter conference where the lead pilot in an EMS single-pilot IFR program let drop a sentence to the effect of "I have trouble getting some of my pilots to use the autopilot." Thinking this was just a fluke, I started checking with lots of other people who fly helicopters with stabilization systems and autopilots. Everyone said the same thing--it appears that 20-25 percent of pilots don't want to use the autopilot in VFR and use it IFR only under protest. Several accidents could be traced to pilots not using the autopilot, not using it properly or getting confused with its use.

Reasons range from "I don't understand it" and "I can fly this thing better than the autopilot" to "It scares me when it does strange things" and "I only use it IFR."

If you don't understand how the autopilot works, you had better find out. It isn't professional to not know the equipment you use every day. You would look extremely foolish in front of any court (terrestrial or otherwise) saying, "Well, no one ever explained it to me" for anything else in the helicopter. Go to school, read books, ask questions!

For those who think they can fly the helicopter better than the autopilot, consider how many excursions in altitude and heading you make as you hand-fly between A and B and how few excursions the autopilot makes. Each of your excursions costs something in fuel, so from an efficiency standpoint alone the autopilot is saving time and money. Not a lot, but it does add up.

If the autopilot does something you don't understand or that it shouldn't, don't be silent about it. NASA has a web site for stories like this, and so does organizations like HAI and the FAA. Send in Service Difficulty Reports. Write it up. But don't say nothing.

The "reasons" why some helicopter pilots don't use the autopilot are little short of astounding, especially when compared to how the professional fixed-wing world operates. Even the lowest commuter airliner will have an autopilot and its use will not be optional. If you decide you don't want to use the autopilot when you fly a regional airliner, you are free to find another job. The company says you will fly this way or you won't fly for the company. And you fly this way regardless of the weather.

Why are we not learning from the fixed-wing side of the house?

There are many good reasons to use an autopilot, even when you're VFR, aside from efficiency. Plug in heading hold and altitude hold and you don't have to worry about making a dirty dart for the ground if you get distracted. You can spend time looking outside for other traffic, programming the GPS, navigating using the map, and so on with confidence. Pipeline patrols in an unstabilized helicopter had me thinking, "This is really a lot of work, and I don't have time to do much else but fly the machine."

A lot of machines with autopilots have a force trim switch, and pilots routinely turn this switch off because they "don't like the stick forces." Little do they realize the majority of features of the stabilization and autopilot are disabled--indeed, the "upper" modes that hold airspeed or fly the ILS, don't work at all without the force trim on.

In my short stint flying EMS, we used to cross the Sierra Nevada mountains at 10,000 ft. and have to descend to 300 ft. at Bakersfield, Calif.--at 10 min. to go on the GPS, it was change the autopilot from altitude hold to airspeed hold and lower the collective to set a 800-1,000 fpm. rate of descent. (Navigation tracking stayed on.) There were no major attitude, airspeed or heading changes through the descent and the backseat medical crew could work without getting bounced around. At 800 ft. msl, it was change back to altitude hold and let the airspeed bleed off to start the approach. Finally, at about 2 nm. disengage the upper modes.

Get familiar with the autopilot in VFR conditions, and you'll be much happier to use it IFR--which is when you need it most. Conversely if you don't use it VFR, you probably won't use it with confidence IFR.

There is no question that the autopilot has a much superior IFR crosscheck to any human pilot. But just like VFR, the side benefits are huge--more time to spend on situational awareness, more time for setting up navigation equipment, more time to study the approach plates. Also, there's no need to worry about altitude violations. Tracking a navaid? It's locked on rails. Couple it up for the ILS and you would think someone glued the glideslope and localizer needles in the middle.

If you're a check pilot of any flavor, do you insist your pilots demonstrate how to use the equipment properly? Even in VFR?

An autopilot, more than nearly any other change to a helicopter, has the capability to make your life easier. Why not use it?

A graduate of the U.K.'s Empire Test School and a former instructor at the U.S. Naval Test Pilot School, Shawn Coyle is the author of Cyclic & Collective.

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