Federal Aviation
Administration

MMEL Policy Letter 39 Revision 5

Date:

January 29, 2010

To:

All Region Flight Standards Division Managers
All Aircraft Evaluation Group Managers

From:

Manager, Air Transportation Division, AFS-200

Reply To
Attn Of:

Manager, Technical Programs Branch, AFS-260

MMEL GLOBAL CHANGE

PL-39 is designated as GC-162

This Global Change (GC) is an approved addendum to all existing MMEL documents.  Operators may seek use of the specific relief contained in this policy letter by revising their Minimum Equipment List (MEL).  In doing so, each applicable sample proviso stating the relief in this policy letter must be copied verbatim in the operatorís MEL.  Approval of a revised MEL is gained utilizing established procedures, through the Operatorís assigned Principal Operations Inspector (POI).

Subject:

Altitude Alerting Systems

MMEL CODE:

34 (NAVIGATION)

REFERENCE:

PL-39, Revision 4, dated September 29, 2008

PL-39, Revision 3, dated March 1, 2001

PL-39, Revision 2, dated August 15, 1997

PL-39, Revision 1, dated March 20, 1991

PL-39, Original, dated February 20, 1990

PURPOSE:

The purpose of this policy letter is to provide standardized master minimum equipment list (MMEL) policy for altitude alerting systems.

DISCUSSION:

Revision 5 reinstates relief for altitude alerting systems as provided in 14 CFR 91.219.  This revision maintains the requirement for operative autopilot altitude hold, restricts flight where enroute operations require its use (i.e., RVSM; ref. PL-84), and stipulates the airplane may not depart a designated airport where repairs can be made.  Added new category of relief for other than turbojet-powered civil airplanes.

Revision 4 withdraws all earlier guidance for the altitude alerting systems.  The PL guidance conflicts with 14 CFR 91.219.

Revision 3 adds appropriate restrictions to indicate that an Altitude Alerting System may be required to be operative for dispatch when operating within certain airspace.  This is in accordance with the policy described in Policy Letter (PL) 84 (Reduced Vertical Separation Minimum (RVSM) Requirements).  It also adds relief for non-turbine aircraft.

Revision 2 reformatted policy letter 39, revision 1, with no change to policy.

Initially the Flight Operations Policy Board (FOPB) determined that some MMELs for turbojet-powered aircraft permitted the altitude alerting system to be inoperative for flight, while others did not.  At industry's request, the original PL-39, which stated that altitude alerting systems must always be operative for flight, was reconsidered.  Operational procedures for crew altitude awareness, as well as autopilot system capabilities were considered in allowing MMEL relief.  As a result, revision 1, granted limited MMEL relief for the altitude alerting system, provided the air carrier had suitable operational procedures, and an operable autopilot with altitude hold capability.

This policy letter standardizes MMEL relief for Altitude Alerting Systems.  This includes provisions based on the fact that the system may be required for operations within certain airspace.  Per the guidance of PL-84, operators must ensure that an Altitude Alerting System is functioning for RVSM operations.

POLICY:  

The FOPB has determined that MMEL relief for the altitude alerting system may be granted.  The provisos will require that the air carrier develop an operational procedure, and will require an operable autopilot that has altitude hold capability.  They will also prohibit dispatch if enroute operations are reliant on their use.  Repair requirements reflect 14 CFR 91.219.  For turbojet-powered civil airplanes that have more than one altitude alerting system installed, those excess systems may be inoperative for category C repair interval.  In addition, relief for altitude alerting system on other than turbojet-powered civil airplanes is provided at category C and prohibits dispatch if enroute operations are reliant on its use.

 

Turbojet-powered civil airplanes

 

ATA 34 NAVIGATION

 

 

 

 

XX-X Altitude Alerting
         System

 

A

 

-

0

(O) May be inoperative provided:

a) Autopilot with altitude hold, and altitude capture operates normally,

b) Enroute operations, ie RVSM, do not require its use,

c) Airplane does not depart from a designated airport (as listed in the operatorís MEL) where repair or replacement can be made, and

d) Repairs are made within 3 flight days.

 

 

C

-

1

 

 

1) Aural Alert

C

-

0

May be inoperative provided:

a) Visual alert operates normally, and

b) Auto-pilot with altitude hold and altitude capture operates normally.

 

2) Visual Alert

C

-

0

May be inoperative provided:

a) Aural alert operates normally, and

b) Auto-pilot with altitude hold and altitude capture operates normally.

 

 

OTHER THAN Turbojet-powered civil airplanes

 

ATA 34 NAVIGATION

Repair Interval

Number Installed

Number Required for Dispatch

Remarks or Exceptions

XX-X Altitude Alerting
         System

 

C

-

0

May be inoperative provided enroute operations, ie RVSM, do not require its use.

 

 

Each Flight Operations Evaluation Board (FOEB) Chairman should apply this Policy to affected MMELs through the normal FOEB process.

 

 

 

 

 

 

 

John Duncan,  Manager,

Air Transportation Division, AFS-200