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.

Look for our daily Aero-Tips segments, coming each day to you through the Aero-News Network.

Aero-Tips 07.26.06

We bat around several terms about flight visibility and ceiling, but sometimes it becomes apparent that they are not completely understood. Let's take a minute to make sure we're all on the same page with in-flight definitions.

• VFR (Visual Flight Riles, or more correctly, VMC, for Visual Meteorological Conditions) means:
• • Visibility is five statute miles or greater and
  • The base of any cloud ceiling is 3000 feet above ground level (AGL) or higher
• MVFR (for Marginal VFR) means either or both:
• • Visibility is between three and five miles and/or
  • The cloud ceiling is 1000 to 3000 feet AGL
• IFR (Instrument Flight Rules, more correctly IMC, for Instrument Meteorological Conditions) means either or both:
• • Visibility is between one and three miles and/or
  • The ceiling is between 500 and 1000 feet AGL
• LIFR (Low IFR) means either or both:
• • Visibility is less than one mile and/or
  • The ceiling is less than 500 feet AGL

(Above is a significant weather plot from the Aviation Weather Center. LIFR reporting points are pink, IFR are red, MVFR are blue, and VFR reporting points are not plotted.)

The terms "MVFR" and "LIFR" are not used in all aviation weather products, so often there is no distinguishing between "VMC" that has 1.1 mile visibility and 100 miles, or that has no ceiling or a 1001-foot ceiling. "IFR" could be zero-zero (no visibility, surface obscured) or it could be one miles visibility in morning haze with clear skies, or it could be a 999-foot ceiling with 200 miles visibility.

Note: even moderate thunderstorms don't always reduce ceiling and visibility below the "VMC" level... so visibility or ceiling alone are not the sole determinants of "good flying weather".

Aero-tip of the day: Use visibility and ceiling reports as the beginning, not the end, of a larger weather investigation.

FMI: Aero-Tips