AOPA - Career Pilot

Need to Know, Nice to Know

Too much information is overload; too little spells trouble

By Vincent Czaplyski (From AOPA Pilot)

My class listened spellbound to the ground school instructor. "You'll be tested every day on the previous day's material," he said dryly. "Anyone who fails to get at least 80 percent" — he paused for dramatic emphasis — "well, just don't get less than that." It was left to our collective imagination to divine what these words meant, but instinctively we knew it couldn't be good. It was the first "real" airline job for all of us, and no one wanted to blow it.

I was learning my first jet, the Douglas DC 9. My classmates' backgrounds ran the gamut from Air Force instructor pilots to corporate and commuter types like myself. For the next several weeks we showed up each day in the classroom, most of us red-eyed from late-night studying and practice oral sessions. Nothing about the DC 9 was too arcane or obscure to escape our attention. If it existed on the airplane, we intended to know about it.

Everyone, that is, except Lenny. When a classmate would wonder why, for instance, a particular electrical relay acted in a certain way, Lenny would smile knowingly, shake his head, and say, "That's nice to know, not need to know." When someone asked why the aircraft wasn't designed to fly at Flight Level 410, or have a longer range or higher speed, his response was inevitably the same. Lenny flew C 141s in the Air National Guard, and we figured he knew what he was talking about. He also consistently got the highest marks on the daily tests, and from what any of us could tell, studied the least. As it turned out, he was on to something. Lenny knew how to focus on what was important and put aside what was not.

Mastering a new aircraft is a process. Considering the amount of information we need to learn, setting priorities is a must. Knowing the difference between meat, fat, and gristle goes a long way toward helping us understand a new type as quickly as possible.

Take the Lear 35 as an example. Suppose you are heading to school to learn all about this aircraft, one you have never set foot in before but will soon be flying in your new corporate job. How to prioritize?

A well-designed course of study to some extent will prioritize for you. It will include certain basics, and these should be considered absolute "need to know" items. For starters, you should come away with a good practical understanding of systems operation. This means, for example, that you should clearly know what is happening within the aircraft whenever a switch is moved, a warning light comes on, or an autopilot mode is changed. You should be able to easily recall any aircraft limitations and memory checklist items, and know when they apply. You need to know cold the various recommended profiles for maneuvers such as stall recoveries, ILS and nonprecision approaches, and single-engine work. Just as important, you need to be mindful of "bottom line" limits that warn when safe operating margins for pilot or airplane are being exceeded. You should definitely understand checklist "flows" and practice good checklist discipline, using normal and nonnormal checklists as needed. Not least of all, you need to be able to put it all together in the course of aircraft or simulator sessions, conducting flights whose safe outcome is never in doubt.

One unavoidable step in the learning process involves passing tests that don't always seem to relate to real-world operation of the aircraft. The oral, for example, requires that you explain to an examiner how each subsystem works, in considerably more detail than you'll ever need to use these systems in everyday operations. Although cynics might describe this as mere regurgitation of useless facts, there is hidden logic at work here. It is in fact an important step in learning the airplane.

For example, the engine fire-detection system on the Lear 35 employs three heat-sensing elements installed within each engine cowling. The electrical resistance of these elements changes in response to heat. The elements are composed of metal tubing filled with a heat-sensitive ceramic material, through the center of which runs a conductor wire. The wire carries a direct current through a detection circuit. At normal temperatures the electrical resistance of the ceramic material is comparatively high, meaning little current flows through the detection circuit. When temperature around the hot section of the engine equates to 890 degrees Fahrenheit or higher, though, the electrical resistance drops. This allows the current to flow between the conductor wire and metal tube, illuminating a red Fire or Eng Fire light in the cockpit. An examiner would expect you to know this and many other detailed facts about this system for an oral exam.

Will all this detail flash through your mind when the Fire light illuminates on some dark and stormy night? Not likely. Your first conscious thought may be something like "The engine's on fire!" But after a couple of seconds you will remember to get out the checklist, which in turn reminds you to place the affected engine thrust lever to Idle. If the fire indication persists for more than 15 seconds, place the thrust lever to Cut-Off and pull the corresponding fire T-handle. This closes the main fuel, hydraulic, and bleed-air shutoff valves for that engine. It also arms two fire extinguishing bottles, which the checklist then tells you to use as needed to control the fire.

Afterward, safely back in the hangar, you may reflect upon the sublime inner workings of the fire detection and suppression system, and appreciate how it worked as designed. But at the time of the emergency did you really need to understand it in as much detail as you did during your oral exam? I doubt it. Did such understanding help you get through the emergency? On some level, I would wager it increased your confidence, and that can only have been a plus. Your subconscious brain probably whispered something like, "Five or six things are conspiring to illuminate that fire light, and I had better take it seriously." Training and rote memory then kicked in, and you responded by saying, " Engine Fire — Shutdown checklist." In other words, your training worked as advertised.

But too much information is still too much. It can make matters worse in an airplane if we let it become a distraction. As Lenny knew intuitively, eliminating extraneous details lets us concentrate on what is most important. Do you need to know how the Lear's air data sensor transforms pitot static inputs into electrical signals? Not unless you are planning a second career as an avionics technician. Should you know that the air data sensor sends these electrical signals to the autopilot and Mach trim computers? Absolutely, since we can expect a malfunctioning air data sensor to affect both of these items. That knowledge is useful while troubleshooting in-flight problems. Most of us have a limited supply of brain cells. Learning to distinguish between "need to know" and "nice to know" makes most efficient use of that supply.

None of this should be taken to mean that you shouldn't constantly aim to become more knowledgeable about your aircraft. On the contrary, "seek and ye shall find" is a good philosophy to live by here. As hours logged in a new type grows, so should your understanding of it. Got a few quiet moments in cruise in that Lear? Get the book out (or your condensed systems notes — it's a tight cockpit) and review the detailed workings of a different system now and then. There's nothing better than having the real airplane right there to help you visualize how something works. Can you still answer every oral question an examiner might throw at you about that system? Chances are you'll refresh a few long-forgotten bits of the puzzle while thinking through the answers.

While you're at it, play some challenging "What if?" scenarios with the pilot seated next to you. How would you work together in the dead of some snowy night when four things just went wrong in short order? Chances are, you will each come up with at least one good idea the other didn't. You'll both enlarge your bag of tricks this way. Going to recurrent training? Why not ask the instructor to show you something in the simulator you might not have seen before, such as recovery from a high-altitude, fully developed stall? Or how about a wind shear encounter during a single-engine missed approach? Either scenario could happen, so why not try them on for size and expand your understanding of the airplane? Just because it isn't required training doesn't mean you can't try it.

Feeling on top of your game? That's definitely nice to know.