N 8900.440


National Policy

Effective Date: 10/27/17



Cancellation Date: 10/27/18



Master Minimum Equipment List Policy Letter 98, Revision 1, Navigation Databases, and Associated Aviation Safety Inspector Requirements

1.    Purpose of This Notice. This notice announces revised policy associated with Master Minimum Equipment List (MMEL) Policy Letter (PL)-98, Navigation Databases. This notice provides guidance to the Aircraft Evaluation Division (AFS-100), which develops and revises MMELs, and aviation safety inspectors (ASI) with minimum equipment list (MEL) oversight responsibility, and tasks them with ensuring all MMELs and operators’ MELs are updated in accordance with this notice and MMEL PL-98, revision 1. This notice also extends the due date for ASIs and AFS-100 to ensure compliance with MMEL PL-98, revision 1.

Note:  The use of the term “operator” in this notice refers to those certificate holders, program managers, foreign air carriers, and aircraft owners utilizing an MMEL or MEL and conducting aircraft operations under Title 14 of the Code of Federal Regulations (14 CFR) parts 91, 91 subpart K (part 91K), 121, 125, 129, and 135, unless otherwise specified.

2.    Audience. The primary audience for this notice is ASIs assigned to AFS-100, and ASIs in Flight Standards offices with oversight responsibility of aircraft operators’ MEL(s). The secondary audience includes all Flight Standards divisions, branches, and offices.

3.    Where You Can Find This Notice. You can find this notice on the MyFAA employee website at Inspectors can access this notice through the Flight Standards Information Management Systems (FSIMS) at Operators can find this notice on the Federal Aviation Administration’s (FAA) website at This notice is available to the public at

4.    Cancellation. This notice cancels Notice N 8900.424, Master Minimum Equipment List Policy Letter 98, Revision 1, Navigation Databases, and Associated Aviation Safety Inspector Requirements, dated June 1, 2017.

5.    Background.

a.    General. The FAA established MMEL relief for out of currency navigation databases on January 20, 1999, through MMEL PL-98, revision 0. In general, the PL allowed MMEL relief and continued use of an out of currency navigation database (without an existing inoperative condition) as long as the operator verified the data used before flight. The PL allowed for repair category C, which is up to 10 days deferral and one-time extendable for another 10 days by the operator.

Note:  The use of the word “item” throughout this notice refers to both instrument and equipment items, as applicable.

b.    Regulatory Requirements. Part 91, 91.213 and 91.1115; part 121, 121.628; part 125, 125.201; part 129, 129.14(b); and part 135, 135.179, Inoperable Instruments and Equipment, in pertinent part, allow for the continued operation of an aircraft with inoperable items installed through the use of an FAA-approved MEL. For any item to be considered for relief under this regulation, including a navigation database, the item must be inoperative.

c.    Definition of Inoperative. Every MMEL and MEL must include the definitions found in MMEL PL-25, MMEL and MEL Definitions. In PL-25, “inoperative” is defined as “a system and/or component malfunction to the extent that it does not accomplish its intended purpose and/or is not consistently functioning normally within its approved operating limit(s) and/or tolerance(s).” An out of currency navigation database that continues to be used for navigation does not fall within the definition of inoperative and cannot be considered as such.

d.    Preamble. Every MMEL and MEL must include the preamble found in MMEL PL-34, MMEL and MEL Preamble (MMEL PL-36, FAR Part 91 MEL Approval & Preamble, contains the preamble for part 91 operators). PL-34 (and PL-36) states, in pertinent part, “The individual operator’s MEL, when approved and authorized, permits operation of the aircraft with inoperative equipment.” Because the out of currency navigation database is not inoperative per the definition, the preamble requirements cannot be complied with and MMEL/MEL relief cannot be applied.

e.    Operations Specification (OpSpec)/Management Specification (MSpec)/Training Specification (TSpec)/Letter of Authorization (LOA) D095. Per 14 CFR, an approved MEL, as authorized by OpSpec/MSpec/TSpec/LOA D095, Minimum Equipment List Authorization—U.S.-Registered Aircraft, is an approved change in type design without requiring recertification of the aircraft. Because an out of currency navigation database is not an inoperative item, there is no resultant change in type design. It cannot be authorized MEL relief per OpSpec/MSpec/TSpec/LOA D095.

6.    Guidance. All ASIs must be familiar with and understand the limitations associated with conducting flight operations utilizing an out of currency navigation database. ASIs must clearly understand that minimum system capabilities and operating margins are based on specific levels of system performance that includes a current navigation database. An operator’s ability to conduct terminal and en route Area Navigation (RNAV) procedures and Required Navigation Performance (RNP) procedures will be limited within national and international airspace if their navigation database is not current. All ASIs should review the current editions of the following advisory circulars (AC) and remain alert for the publication of the updated guidance associated with current navigation databases:

    AC 20-138, Airworthiness Approval of Positioning and Navigation Systems (chapters 8, 10, 12, and appendix 2).

    AC 20-153, Acceptance of Aeronautical Data Processes and Associated Databases (paragraph 13).

    AC 90-100, U.S. Terminal and En Route Area Navigation (RNAV) Operations (paragraphs 10 and 11).

    AC 90-101, Approval Guidance for RNP Procedures with AR (appendices 3–5).

    AC 90-105, Approval Guidance for RNP Operations and Barometric Vertical Navigation in the U.S. National Airspace System and in Oceanic and Remote Continental Airspace (chapter 8, and appendices A and B).

7.    Action.

a.    AFS-100. AFS-100 will revise all MMELs that contain navigation database relief to ensure compliance with MMEL PL-98, revision 1, at either the next revision or within 2 years (24 months) of the effective date of this notice, whichever comes earlier. AFS-100 managers and the Air Transportation Division (AFS-200) will monitor to ensure compliance to this requirement.

b.    ASIs.

(1)    Inspectors will ensure that operators with approved out of currency navigation database relief revise/update their MEL/MMEL for compliance with MMEL PL-98, revision 1. This shall be completed within 90 days after AFS-100 has revised the applicable MMEL’s navigation database relief. Normal MEL revision approval procedures will be used to record the completion of this requirement. Responsible Flight Standards office managers will monitor using internal office procedures to ensure compliance to this requirement.
(2)    Review operator procedures for aircraft operation with an out of currency navigation database. If deficiencies are identified, ASIs will work with the operator to achieve an acceptable level of compliance with the database currency requirements found in the aforementioned ACs. In many, if not most cases, operator procedures developed for MEL compliance to MMEL PL-98, revision 0, should be acceptable for continued use.

8.    Disposition. The information in this notice will not be incorporated into FAA Order 8900.1. MMEL PL-98, revision 1, will remain in effect until revised or rescinded. Direct questions concerning the information in this notice to AFS-200 at 202-267-8166.


/s/ John Barbagallo

Deputy Executive Director, Flight Standards Service