AIM ¶ 4-6-8 — RVSM Phraseology
AIM 4-6-8: Standard pilot/controller phraseology for RVSM operations, including 'Affirm RVSM,' 'Negative RVSM,' and 'Unable RVSM Due Equipment' calls.
In Plain English
AIM 4-6-8 lists the standard phraseology pilots and controllers use in Domestic Reduced Vertical Separation Minimum (DRVSM) operations between FL290 and FL410. Knowing these exact phrases is critical because RVSM airspace requires special aircraft and operator approval, and ATC must verify your status before issuing clearances.
Key phrases to memorize:
- "Confirm RVSM approved" — controller asking about your aircraft's RVSM status.
- "Affirm RVSM" — pilot confirms the flight is RVSM approved.
- "Negative RVSM, (reason)" — pilot reports non-RVSM status (e.g., certification flight). Used on initial call on any RVSM-airspace frequency, in all flight level change requests, and in read-backs of clearances within or climbing/descending through RVSM airspace.
- "Unable RVSM Due Equipment" — pilot reports failure of all primary altimeters, automatic altitude control systems, or altitude alerters after entering RVSM airspace. Use until the problem is resolved or you exit RVSM airspace.
- "Unable issue clearance into RVSM airspace, maintain FL___" — ATC denial.
- "Unable RVSM due (reason)" — pilot can't hold altitude due to weather (turbulence, mountain wave).
- "Confirm able to resume RVSM" / "Ready to resume RVSM" — used to return to RVSM operations after a contingency.
These phrases give controllers immediate situational awareness when separation standards may be compromised.
AIM Source Text
FAA AIM ¶ 4-6-84-6-8. 4-6-8. Pilot/Controller Phraseology
TBL 4-6-1 shows standard phraseology that pilots and controllers will use to communicate in DRVSM operations. TBL 4-6-1 Pilot/Controller Phraseology Message Phraseology For a controller to ascertain the RVSM approval status of an aircraft: (call sign) confirm RVSM approved Pilot indication that flight is RVSM approved Affirm RVSM Pilot report of lack of RVSM approval (non-RVSM status). Pilot will report non-RVSM status, as follows: Negative RVSM, (supplementary information, e.g., “Certification flight”). On the initial call on any frequency in the RVSM airspace and . . .. b. In all requests for flight level changes pertaining to flight levels within the RVSM airspace and . . .. c. In all read backs to flight level clearances pertaining to flight levels within the RVSM airspace and . . .. d. In read back of flight level clearances involving climb and descent through RVSM airspace (FL 290 - 410). NOTE- Pilot report of one of the following after entry into RVSM airspace: all primary altimeters, automatic altitude control systems or altitude alerters have failed. (See paragraph 4-6-9 , Contingency Actions: Weather Encounters and Aircraft System Failures that Occur After Entry into RVSM Airspace.) This phrase is to be used to convey both the initial indication of RVSM aircraft system failure and on initial contact on all frequencies in RVSM airspace until the problem ceases to exist or the aircraft has exited RVSM airspace. Unable RVSM Due Equipment ATC denial of clearance into RVSM airspace Unable issue clearance into RVSM airspace, maintain FL *Pilot reporting inability to maintain cleared flight level due to weather encounter. (See paragraph 4-6-9 , Contingency Actions: Weather Encounters and Aircraft System Failures that Occur After Entry into RVSM Airspace.). *Unable RVSM due (state reason) (e.g., turbulence, mountain wave) ATC requesting pilot to confirm that an aircraft has regained RVSM-approved status or a pilot is ready to resume RVSM Confirm able to resume RVSM Pilot ready to resume RVSM after aircraft system or weather contingency Ready to resume RVSM
Oral Exam Questions a DPE Might Ask
Q1What phraseology do you use to confirm your aircraft is RVSM approved when queried by ATC?
Per AIM 4-6-8, the pilot responds 'Affirm RVSM' to confirm RVSM approval, or 'Negative RVSM' followed by supplementary information (e.g., 'Certification flight') if the aircraft is not RVSM approved.
Q2If your altimeter or altitude-hold equipment fails after entering RVSM airspace, what do you tell ATC?
Per AIM 4-6-8, the pilot reports 'Unable RVSM Due Equipment.' This phrase is used both on the initial notification and on initial contact on every subsequent frequency in RVSM airspace until the failure is resolved or the aircraft exits RVSM airspace.
Q3What phraseology applies if turbulence or mountain wave activity prevents you from maintaining your RVSM-cleared flight level?
Per AIM 4-6-8, the pilot states 'Unable RVSM due (state reason),' such as 'Unable RVSM due turbulence' or 'mountain wave.' When conditions improve, the pilot advises 'Ready to resume RVSM,' typically in response to ATC's 'Confirm able to resume RVSM.'
Related Paragraphs in AIM Chapter 4