Aeronautical Information Manual (AIM), page 499

Index   498 -- Page 499 -- 500


Airport Identifier

John F. Kennedy Intl Airport KJFK

LaGuardia Airport KLGA
Kansas City Intl Airport KMCI
Orlando Intl Airport KMCO

Midway Intl Airport KMDW

Memphis Intl Airport KMEM
Miami Intl Airport KMIA
General Mitchell Intl Airport KMKE
Minneapolis St. Paul Intl Airport KMSP

Louis Armstrong New Orleans Intl Air- KMSY

Will Rogers World Airport KOKC

O'Hare Intl Airport KORD
Palm Beach Intl Airport KPBI
Philadelphia Intl Airport KPHL
Pittsburgh Intl Airport KPIT
Raleigh-Durham Intl Airport KRDU

Louisville Intl Airport KSDF
Salt Lake City Intl Airport KSLC
Lambert-St. Louis Intl Airport KSTL

Tampa Intl Airport KTPA
Tulsa Intl Airport KTUL

7-1-26. PIREPs Relating to Volcanic Ash

a. Volcanic eruptions which send ash into the
upper atmosphere occur somewhere around the world
several times each year. Flying into a volcanic ash
cloud can be extremely dangerous. At least two
B747s have lost all power in all four engines after
such an encounter. Regardless of the type aircraft,
some damage is almost certain to ensue after an
encounter with a volcanic ash cloud. Additionally,
studies have shown that volcanic eruptions are the
only significant source of large quantities of sulphur
dioxide (SO2) gas at jet-cruising altitudes. Therefore,
the detection and subsequent reporting of SO2 is of
significant importance. Although SO2 is colorless, its
presence in the atmosphere should be suspected when
a sulphur-like or rotten egg odor is present throughout
the cabin.

b. While some volcanoes in the U.S. are
monitored, many in remote areas are not. These

unmonitored volcanoes may erupt without prior
warning to the aviation community. A pilot observing
a volcanic eruption who has not had previous
notification of it may be the only witness to the
eruption. Pilots are strongly encouraged to transmit a

PIREP regarding volcanic eruptions and any
observed volcanic ash clouds or detection of sulphur
dioxide (SO2) gas associated with volcanic activity.
c. Pilots should submit PIREPs regarding volcanic
activity using the Volcanic Activity Reporting (VAR)
form as illustrated in Appendix 2. If a VAR form is
not immediately available, relay enough information

to identify the position and type of volcanic activity.

d. Pilots should verbally transmit the data required
in items 1 through 8 of the VAR as soon as possible.
The data required in items 9 through 16 of the VAR
should be relayed after landing if possible.
7-1-27. Thunderstorms

a. Turbulence, hail, rain, snow, lightning, sus-
tained updrafts and downdrafts, icing conditions-all
are present in thunderstorms. While there is some

evidence that maximum turbulence exists at the
middle level of a thunderstorm, recent studies show
little variation of turbulence intensity with altitude.
b. There is no useful correlation between the
external visual appearance of thunderstorms and the
severity or amount of turbulence or hail within them.
The visible thunderstorm cloud is only a portion of a
turbulent system whose updrafts and downdrafts
often extend far beyond the visible storm cloud.
Severe turbulence can be expected up to 20 miles
from severe thunderstorms. This distance decreases
to about 10 miles in less severe storms.

c. Weather radar, airborne or ground based, will
normally reflect the areas of moderate to heavy
precipitation (radar does not detect turbulence). The
frequency and severity of turbulence generally
increases with the radar reflectivity which is closely
associated with the areas of highest liquid water
content of the storm. NO FLIGHT PATH THROUGH
d. Turbulence beneath a thunderstorm should not
be minimized. This is especially true when the

Meteorology 7-1-55

Page 499 of the Aeronautical Information Manual (AIM.pdf)
AIM: Official Guide to Basic Flight Information and ATC Procedures

Index   498 -- Page 499 -- 500