Insights

Regulations versus reality

Name the most important cockpit instrument. I like to ask pilots that question even though most responses make my head spin. Common sense is usually ambushed by one's knowledge of the federal aviation regulations. We're in trouble if pilots believe that regulations have the answers to all questions and all dilemmas.

Yes, FAR 91.205 specifies the instruments required for the intended operation, and the airplane flight manual's equipment list specifies the instruments required for airworthiness. Those requirements, however, say nothing about the relative importance of the instruments.

Do we really need instruments to fly an airplane in visual conditions? I hope you said no. Let's start with a blank instrument panel. No instruments whatsoever. Can you fly all the visual maneuvers listed in the Private Pilot Practical Test Standards without instrument reference? If not, you've been cheated, snookered, and robbed during flight training. The wing and throttle positions, engine noise, airflow noise, and control feel provide enough basic information for a properly trained pilot to fly safely.

The first instrument I'll add to that panel is a magnetic compass. It has top priority. I need it to fly specific courses and remain oriented during flights beyond the local area, and regardless of the amount or type of cockpit instrumentation, I will always make certain that the compass indicates properly before every takeoff--something that pilots frequently ignore.

The compass must be full of fluid (fluid level not visible), and while taxiing it must move freely when turning and be accurate when parallel to and perpendicular to the runway. When mechanics swing the compass, they adjust the east-west and north-south compensating magnets (located behind the compass deviation card) until errors are minimized. However, if one magnet gets out of adjustment, the compass may be correct on one heading, but incorrect when turned 90 degrees.

Next, I want a clock. Time, distance, and groundspeed are required for navigation. Time and known fuel consumption are required for fuel-remaining calculations.

Engine health and limitations follow: oil pressure and oil temperature gauges for certain. And to be in full command of the engine--the device in which I place tremendous trust--I'll add a tachometer and a cylinder head temperature gauge.

Now, I'll add an airspeed indicator so that I can reference the airframe's speed limitations: maneuvering (V_A), maximum flaps extended (V_FE), maximum structural cruise (V_NO), never exceed (V_NE), and the normal speeds for climbs and descents. And I can now determine the approximate true airspeed (TAS): indicated airspeed (IAS) plus two percent per 1,000 feet of altitude. If IAS is 105 knots at 4,500 feet, TAS is about 115 knots (105 plus nine percent of 105).

If the rule of thumb for TAS does not provide the accuracy you think is necessary, add an outside air temperature gauge. But remember this: The most critical navigation elements are ground track, groundspeed, and fuel consumption. Wind velocity and direction are important, but they are the least accurate, so the rule of thumb does work.

The altimeter is next. I can now avoid Class B, C, and D airspace and comply with the altitude rule for my magnetic course when flying more than 3,000 feet above ground level. I did not mention traffic pattern altitude because it can be easily determine without altimeter reference. I kid you not. Learn to estimate when you're 1,000 feet above ground level (agl) and then check your altimeter. You'll soon be able to do it consistently, and that awareness is critically important for actual or simulated forced landings.

OK, it's your turn. Add whatever else you want to the panel, but always remember what you learned when you flew with no instruments: You kept a sharp eye on the cockpit framework in relation to the Earth's surface in order to monitor attitude and detect small yaw, pitch, and roll changes. You made immediate control inputs when undesirable changes occurred, particularly with the rudder so that a reasonable yaw rate occurred for the existing bank angle and airspeed--that's how you kept the slip indicator's ball centered without staring at it.

When you take this approach to flying, it becomes easier and you'll fly with more confidence. So keep your eyes pointed outside the cockpit, and make an occasional glance inside for specific information. Studies have proved that a good pilot's scan cycle consists of 16 seconds outside the cockpit followed by four seconds inside. Instrument reference is not the first step for proper aircraft control during visual conditions.

Ralph Butcher, a retired United Airlines captain, is the chief flight instructor at a California flight school. He has been flying since 1959 and has 25,000 hours in fixed- and rotary-wing aircraft. Visit his Web site.