IRFP-01
Metro Review
(4) Rotor turbulence very severe below tops of mountains,
especially near rotor cloud formation—similar to turbulence
associated with thunderstorms but much stronger
(5) Can be identified by cap clouds on mountain top or
standing lenticular clouds along the crests of the flow if
moisture is sufficient
c.
Other areas: can develop in areas where large differences
exist in air mass temperature (e.g., inversions)
2. Operational considerations
a. To prevent structural damage, maintain appropriate speed
(250 KIAS)
b. Severe downdrafts require higher terrain clearance minimums
c.
Avoid rotor clouds, which have enough strength to literally
break aircraft apart
G. Wake turbulence 21.1.1.4.4
1. Characteristics
a. By-product of lift as aircraft takes off or before aircraft touches
down, generated by pressure differential between upper and
lower wind surfaces, causing air under wing to “roll up” around
end of the wing, forming a vortex
NOTE: During landing, wingtip vortex disappears as the
aircraft touches down.
b. Heavy and slow aircraft generate greatest vortex strength
NOTE: Tangential velocities of wingtip vortices have reached
133 kts in tests.
c.
Vortices spread downward at approximately 400 to 500 fpm
from the flight path and outward at approximately 5 kts,
leveling off about 900 ft below flight path
d. Persists several minutes after generating aircraft is out of sight
e. Calm or light surface wind can carry vortices into next aircraft’s
flight path—light quartering tail wind requires maximum caution
2. Operational considerations
a. Plan a landing approach above approach path of previous
aircraft and land beyond touchdown point
(8-97) Original
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