Aero-Tips!

A good pilot is always learning -- how many times have you heard this old standard throughout your flying career? There is no truer statement in all of flying (well, with the possible exception of "there are no old, bold pilots.")

Aero-News has called upon the expertise of Thomas P. Turner, master CFI and all-around-good-guy, to bring our readers -- and us -- daily tips to improve our skills as aviators. Some of them, you may have heard before... but for each of us, there will also be something we might never have considered before, or something that didn't "stick" the way it should have the first time we memorized it for the practical test.

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Aero-Tips 09.22.06

Imagine launching into poor visibility or night conditions with anything less than optimal flight instruments. Or losing use of a primary flight instrument in instrument or dark night conditions and only then learn that one of your supporting instruments is broken. It's vital before taking off into reduced visibility of any sort (including nighttime) to verify the proper operation of your flight instruments.

Airspeed indicator (ASI). Starting at the upper left of a standard instrument panel layout, before takeoff check that the indicated airspeed makes sense. Most pilots will tell you to check that the ASI reads zero, and in most cases that's right. But as I write this the wind outside is blowing at about 40 knots (hey, it's Kansas). If I was in an airplane pointed into the wind on the ramp I'd expect the airspeed indicator to indicate around 40 knots. If it didn't, I'd suspect something was wrong.

Attitude indicator (or Artificial Horizon, or with a flight director an Attitude Director Indicator). Check the AI(AH/ADI) to see it is spun up and indicates wings-level flight. It should not indicate a bank of more than five degrees during taxi turns (it really shouldn't show a bank at all on the ground). Any flags on the instrument (that indicate failure) should be retracted out of sight. Now's a good time to check the vacuum/instrument air pressure gauge and any other pneumatic indicators for proper values, too.

Altimeter. With the current altimeter setting dialed in, the altimeter should indicate +75 feet of the published field elevation. You may have to take airport slope into account; in extreme cases of difference in elevation at points on the airport, you'll find information in the Airport Facilities Directory.

Magnetic compass. Continuing a "flow check" across the top of most panels, check that the magnetic compass is full of fluid, that it moves freely during taxi turns, and that it indicates known headings. The reading may be affected by metal near the compass (for instance, a handheld GPS on the glareshield), or when unusual electrical loads are turned on (like windshield anti-ice or air conditioners).

Vertical speed indicator (VSI). Not required for IFR flight, the VSI is nonetheless a vital aid in attitude flying. Note the "level flight" indication on the VSI while you are on the ground (it may not be the "zero" point). Use the noted indication as the level setting in flight, and adjust your reading of climbs and descents on the gauge accordingly.

Heading indicator (or Directional Gyro, or Horizontal Situation Indicator). Check that the HI/DG/HSI turns freely, indicates known headings and (subject to compass errors) generally agrees with the magnetic compass. It should not precess noticeably during the typical time from startup/setting to takeoff. Any instrument flags should be retracted; check the power source (vacuum/instrument air/electric as appropriate) and, for HSIs, confirm the salving system is turned on.

Turn coordinator/Turn and Bank. Check that the gyro is spinning and there are no flags (sometimes there's a red indicator in a tiny window on the instrument's face). Check that, during taxi turns, the device shows a rate of turn in the same direction, and the slip/skid ball swings to the direction opposite the turn.

Glass cockpit pilots need to check all indicators and power sources with a similar flow check. Don't forget to include those critical back-up "steam gauges" in your preflight checks as well-they're your only backup to a single-point Attitude and Heading Reference System (AHRS) failure, and they'll do you no good in an emergency if they're not accurate.

Aero-tip of the day: Get in the habit of quickly checking flight instruments before every takeoff, so it'll be second nature when you prepare for a low-visibility flight.

FMI: Aero-Tips