TBL 7-1-8

PIREP Element Code Chart
PIREP ELEMENT

PIREP CODE

CONTENTS

3-letter station identifier
Report type
Location
Time
Altitude
Type Aircraft
Sky cover

XXX
UA or UUA
/OV
/TM
/FL
/TP
/SK

Weather
Temperature
Wind
Turbulence
Icing
Remarks

Nearest weather reporting location to the reported phenomenon
Routine or Urgent PIREP
In relation to a VOR
Coordinated Universal Time
Essential for turbulence and icing reports
Essential for turbulence and icing reports
Cloud height and coverage (sky clear, few, scattered, broken, or
overcast)
Flight visibility, precipitation, restrictions to visibility, etc.
Degrees Celsius
Direction in degrees magnetic north and speed in knots
See AIM paragraph 7-1-21
See AIM paragraph 7-1-19
For reporting elements not included or to clarify previously
reported items

/WX
/TA
/WV
/TB
/IC
/RM

7-1-19. PIREPs Relating to Airframe Icing
a. The effects of ice on aircraft are cumulative-thrust is reduced, drag increases, lift lessens, and weight
increases. The results are an increase in stall speed and a deterioration of aircraft performance. In extreme cases,
2 to 3 inches of ice can form on the leading edge of the airfoil in less than 5 minutes. It takes but 1/2 inch of ice
to reduce the lifting power of some aircraft by 50 percent and increases the frictional drag by an equal percentage.
b. A pilot can expect icing when flying in visible precipitation, such as rain or cloud droplets, and the
temperature is between +02 and -10 degrees Celsius. When icing is detected, a pilot should do one of two things,
particularly if the aircraft is not equipped with deicing equipment; get out of the area of precipitation; or go to
an altitude where the temperature is above freezing. This "warmer" altitude may not always be a lower altitude.
Proper preflight action includes obtaining information on the freezing level and the above freezing levels in
precipitation areas. Report icing to ATC, and if operating IFR, request new routing or altitude if icing will be a
hazard. Be sure to give the type of aircraft to ATC when reporting icing. The following describes how to report
icing conditions.
1. Trace. Ice becomes noticeable. The rate of accumulation is slightly greater than the rate of sublimation.
A representative accretion rate for reference purposes is less than  inch (6 mm) per hour on the outer wing. The
pilot should consider exiting the icing conditions before they become worse.
2. Light. The rate of ice accumulation requires occasional cycling of manual deicing systems to minimize
ice accretions on the airframe. A representative accretion rate for reference purposes is  inch to 1 inch (0.6 to
2.5 cm) per hour on the unprotected part of the outer wing. The pilot should consider exiting the icing condition.
3. Moderate. The rate of ice accumulation requires frequent cycling of manual deicing systems to
minimize ice accretions on the airframe. A representative accretion rate for reference purposes is 1 to 3 inches
(2.5 to 7.5 cm) per hour on the unprotected part of the outer wing. The pilot should consider exiting the icing
condition as soon as possible.
4. Severe. The rate of ice accumulation is such that ice protection systems fail to remove the accumulation
of ice and ice accumulates in locations not normally prone to icing, such as areas aft of protected surfaces and
any other areas identified by the manufacturer. A representative accretion rate for reference purposes is more than
3 inches (7.5 cm) per hour on the unprotected part of the outer wing. By regulation, immediate exit is required.

7-1-46

Meteorology