RVSM Wake Turbulence

AIM ¶ 4-6-7 RVSM Wake Turbulence

AIM 4-6-7 wake turbulence guidance for RVSM operations: when to expect encounters, mitigation options, and lateral offset rules for pilot students.

In Plain English

AIM 4-6-7 provides guidance on wake turbulence in RVSM (Reduced Vertical Separation Minimum) airspace, where aircraft are separated by only 1,000 feet vertically between FL290 and FL410. Operational experience — both in the U.S. and Europe — has shown wake encounters in RVSM are typically moderate or less, similar to moderate clear-air turbulence, and have not been a significant safety issue.

When to be alert for wake turbulence:

  • Near aircraft climbing or descending through your altitude
  • About 10–30 miles after passing 1,000 ft below opposite-direction traffic
  • About 10–30 miles behind and 1,000 ft below same-direction traffic

Mitigation options if you encounter or expect wake turbulence in DRVSM airspace:

  • Request a vector
  • Request a flight level change
  • If capable, request a lateral offset (about a wingspan upwind is usually enough to clear the vortex)

In domestic U.S. airspace, pilots must request ATC clearance before flying a lateral offset. Oceanic strategic lateral offsets do not apply here. This is recommended FAA guidance, not a regulatory requirement, but it's important checkride knowledge for high-altitude operations.

AIM Source Text
FAA AIM ¶ 4-6-7
4-6-7. 4-6-7. Guidance on Wake Turbulence 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. 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. 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-month period). In addition, they found that reported wake turbulence was generally similar to moderate clear air turbulence. Pilot Action to Mitigate Wake Turbulence Encounters Pilots should be alert for wake turbulence when operating: In the vicinity of aircraft climbing or descending through their altitude. Approximately 10-30 miles after passing 1,000 feet below opposite-direction traffic. Approximately 10-30 miles behind and 1,000 feet below same-direction traffic. 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- Offsets of approximately a wing span upwind generally can move the aircraft out of the immediate vicinity of another aircraft's wake vortex. In domestic U.S. airspace, pilots must request clearance to fly a lateral offset. Strategic lateral offsets flown in oceanic airspace do not apply.
Oral Exam Questions a DPE Might Ask
Q1In RVSM airspace, when should pilots be especially alert for wake turbulence?
Per AIM 4-6-7, pilots should be alert when operating near aircraft climbing or descending through their altitude, approximately 10–30 miles after passing 1,000 feet below opposite-direction traffic, and approximately 10–30 miles behind and 1,000 feet below same-direction traffic.
Q2What options does a pilot have when encountering or anticipating wake turbulence in DRVSM airspace?
Per AIM 4-6-7, the pilot may request a vector, a flight level change, or — if capable — a lateral offset. An offset of roughly a wingspan upwind generally moves the aircraft clear of the wake vortex.
Q3Can a pilot fly a lateral offset on their own initiative in domestic U.S. RVSM airspace?
No. Per AIM 4-6-7, in domestic U.S. airspace pilots must request a clearance from ATC to fly a lateral offset. Strategic lateral offsets used in oceanic airspace do not apply domestically.
Related Paragraphs in AIM Chapter 4
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AIM 4-6-7 — Wake Turbulence in RVSM Airspace