Operational considerations regarding penetration of thunderstorms

Metro-01

Review of Basic Meteorological Principles

(c) Areas of low precipitation and/or low turbulence

indicate high probability of lightning; conversely, in

areas of high precipitation and/or turbulence, the

probability of lightning is low

NOTE: Storms with high rates of natural lightning

indicates a low probability of aircraft strikes.

(d) There is a greater probability of lightning strikes to

aircraft during storm's decaying stages

(e) The highest probability for direct lightning strikes to

aircraft are in those parts of the storm where ambient

temperature is lower than -40 degrees C (pressure

altitude off 38,000 ft to 40,000 ft)

(f) Most lightning strikes to aircraft are triggered by the

aircraft itself

NOTE: When flying in or around thunderstorms, the

probability of lightning strikes exist at all altitudes.

Therefore, the only proven way to avoid lightning strikes

is to avoid thunderstorms by a wide margin when

possible.

3. Operational considerations regarding penetration of thunderstorms

NOTE: Thunderstorms present many hazards and should be

avoided whenever possible. In the event penetration cannot be

avoided, the following NATOPS procedures should be utilized to

minimize the danger.

a. Before penetration

(1) Plan a course to take you through the storm in a minimum

amount of time, and do not alter it

(2) Penetrate at an altitude where the outside air temperature

(OAT) is colder than -15 degrees C or warmer than

+15 degrees C

(3) HALT

(a) Heat

i.

Pitot heat switch - CHECK ON

(b) Airspeed/Attitude

i.

Maintain turbulence penetration airspeed of

250 KIAS

ii.

Go on instruments and stabilize airspeed and

attitude prior to penetrating the storm

(7-97) Original

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