AIM 

4/20/23

 

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Operational Policy/Procedures for Reduced Vertical Separation Minimum (RVSM) in the

Domestic U.S., Alaska, Offshore Airspace and the San Juan FIR

3. MWA.

When pilots encounter MWA, they should contact ATC and report the magnitude and location

of the wave activity. When a controller makes a merging targets traffic call, the pilot may request a vector to avoid
flying directly over or under the traffic. In situations where the pilot is experiencing altitude deviations of 200
feet or greater, the pilot will request a vector to avoid traffic. Until the pilot reports clear of MWA, the controller
will apply merging target vectors to one or both passing aircraft to prevent their targets from merging:

EXAMPLE

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“Yankee 123, FL 310, unable RVSM due mountain wave.”
 
“Yankee 123, fly heading 290; traffic twelve o’clock, 10 miles, opposite direction; eastbound MD

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80 at FL 320” (or the

controller may issue a vector to the MD

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80 traffic to avoid Yankee 123).

4. FL Change or Re

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route.

To leave airspace where MWA or severe turbulence is being encountered, the

pilot may request a FL change and/or re

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route, if necessary.

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7. Guidance on Wake Turbulence

a.

Pilots should be aware of the potential for wake turbulence encounters in RVSM airspace. Experience

gained since 1997 has shown that such encounters in RVSM airspace are generally moderate or less in magnitude.

b.

Prior to DRVSM implementation, the FAA established provisions for pilots to report wake turbulence

events in RVSM airspace using the NASA Aviation Safety Reporting System (ASRS). A “Safety Reporting”
section established on the FAA RVSM Documentation web page provides contacts, forms, and reporting
procedures.

c.

To date, wake turbulence has not been reported as a significant factor in DRVSM operations. European

authorities also found that reports of wake turbulence encounters did not increase significantly after RVSM
implementation (eight versus seven reports in a ten

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month period). In addition, they found that reported wake

turbulence was generally similar to moderate clear air turbulence.

d.

Pilot Action to Mitigate Wake Turbulence Encounters

1.

Pilots should be alert for wake turbulence when operating:

(a)

In the vicinity of aircraft climbing or descending through their altitude.

(b)

Approximately 10

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30  miles after passing 1,000 feet below opposite

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direction traffic.

(c)

Approximately 10

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30 miles behind and 1,000 feet below same

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direction traffic.

2.

Pilots encountering or anticipating wake turbulence in DRVSM airspace have the option of requesting

a vector, FL change, or if capable, a lateral offset.

NOTE

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1.

Offsets of approximately a wing span upwind generally can move the aircraft out of the immediate vicinity of another

aircraft’s wake vortex.

2.

In domestic U.S. airspace, pilots must request clearance to fly a lateral offset. Strategic lateral offsets flown in oceanic

airspace do not apply.

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8. Pilot/Controller Phraseology

TBL 4

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1 shows standard phraseology that pilots and controllers will use to communicate in DRVSM

operations.