AIM 4-6-9

TBL 4-6-2 provides pilot guidance on actions to take under certain conditions of aircraft system failure that occur after entry into RVSM airspace and weather encounters. It also describes the expected ATC controller actions in these situations. It is recognized that the pilot and controller will use judgment to determine the action most appropriate to any given situation.

TBL 4-6-9 Contingency Actions: Weather Encounters and Aircraft System Failures that Occur After Entry into RVSM Airspace

Initial Pilot Actions in Contingency Situations

Initial pilot actions when unable to maintain flight level (FL) or unsure of aircraft altitude-keeping capability:

•Notify ATC and request assistance as detailed below.

•Maintain cleared flight level, to the extent possible, while evaluating the situation.

•Watch for conflicting traffic both visually and by reference to TCAS, if equipped .

•Alert nearby aircraft by illuminating exterior lights (commensurate with aircraft limitations).

Severe Turbulence and/or Mountain Wave Activity (MWA) Induced

Altitude Deviations of Approximately 200 feet

Pilot will:

Controller will:

•When experiencing severe turbulence and/or MWA induced altitude deviations of approximately 200 feet or greater, pilot will contact ATC and state “Unable RVSM Due (state reason)” (e.g., turbulence, mountain wave)•If not issued by the controller, request vector clear of traffic at adjacent FLs

•If desired, request FL change or re-route

•Report location and magnitude of turbulence or MWA to ATC

•Vector aircraft to avoid merging target with traffic at adjacent flight levels, traffic permitting

•Advise pilot of conflicting traffic

•Issue FL change or re-route, traffic permitting

•Issue PIREP to other aircraft

See paragraph 4-6-6 , Guidance on Severe Turbulence and Mountain Wave Activity (MWA) for detailed guidance.

Paragraph 4-6-6 explains “traffic permitting.”

Mountain Wave Activity (MWA) Encounters - General

Pilot actions:

Controller actions:

•Contact ATC and report experiencing MWA

•If so desired, pilot may request a FL change or re-route

•Report location and magnitude of MWA to ATC

•Advise pilot of conflicting traffic at adjacent FL

•If pilot requests, vector aircraft to avoid merging target with traffic at adjacent RVSM flight levels, traffic permitting

•Issue FL change or re-route, traffic permitting

•Issue PIREP to other aircraft

See paragraph 4-6-6 for guidance on MWA.

Paragraph 4-6-6 explains “traffic permitting.”

NOTE-

MWA encounters do not necessarily result in altitude deviations on the order of 200 feet. The guidance below is intended to address less significant MWA encounters.

Wake Turbulence Encounters

Pilot should:

Controller should:

•Contact ATC and request vector, FL change or, if capable, a lateral offset

•Issue vector, FL change or lateral offset clearance, traffic permitting

See paragraph 4-6-7 , Guidance on Wake Turbulence.

Paragraph 4-6-6 explains “traffic permitting.”

“Unable RVSM Due Equipment”

Failure of Automatic Altitude Control System, Altitude Alerter or All Primary Altimeters

Pilot will:

Controller will:

•Contact ATC and state “Unable RVSM Due Equipment”

•Request clearance out of RVSM airspace unless operational situation dictates otherwise

•Provide 2,000 feet vertical separation or appropriate horizontal separation

•Clear aircraft out of RVSM airspace unless operational situation dictates otherwise

One Primary Altimeter Remains Operational

Pilot will:

Controller will:

•Cross check stand-by altimeter

•Notify ATC of operation with single primary altimeter

•If unable to confirm primary altimeter accuracy, follow actions for failure of all primary altimeters

•Acknowledge operation with single primary altimeter

Transponder Failure

Pilot will:

Controller will:

•Contact ATC and request authority to continue to operate at cleared flight level

•Comply with revised ATC clearance, if issued

•Consider request to continue to operate at cleared flight level

•Issue revised clearance, if necessary

NOTE-

14 CFR section 91.215 (ATC transponder and altitude reporting equipment and use) regulates operation with the transponder inoperative.