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 07.19.06

Many tower-controlled airports report Runway Visual Range. RVR is the distance a pilot can see runway surface markings or lights when aligned with the runway centerline.

Note: This differs from reported "visibility", which refers to the distance at which a defined object or light can be seen and recognised or identified. Typically the RVR will be 1.5 to 3 times the visibility in any given conditions, depending on the nature of the obscuring medium, according to Wikipedia.

RVR is determined by transmissometers, mechanical devises that measure distance by shooting a light beam and determining how much it scatters over a known distance-mounted on towers 14 feet high stationed 250 feet apart.  Any obscuring matter (rain, snow, dust, fog, haze or smoke) reduces the light intensity arriving at the receiver. The measurement is then automatically converted to an RVR value, updated approximately once every minute. The information is displayed in Air Traffic Control tower cab, and controllers relay RVR data to pilots.

• Most transmissometers can detect RVR as low as 200 feet, and report RVR in:
• • 200-foot increments to 3000 feet (half a nautical mile), and
  • 500-foot increments from there to the highest reported range, 6000 feet (one nautical mile).
• New-generation RVR devices report RVR in:
• • 100-foot increments from zero to 800 foot RVR,
  • 200-foot increments from 800 feet to 3000 feet RVR, and
  • 500-foot increments from 3000 feet to a maximum 6500 feet RVR.
• New-generation RVR also reports in meters at airports where the metric system is used for visibility reports.

Pilots must comply with RVR approach minimums for the type of approach and their approach certification.

There are regulatory provisions for odd-distance RVRs (e.g., 150-foot for CAT IIIb approaches) at airports with earlier-generation transmissometers.

Aero-tip of the day: Know what Air Traffic Control means when it gives you an RVR report -- and how to use RVR to safely complete your flight.

FMI: Aero-Tips