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Federal Aviation Administration
Washington, DC

MMEL Policy Letter 105, Revision 2

Date:                                         12/04/2017

To:                                            Manager, Aircraft Evaluation Division (AFS-100)
    All Aircraft Evaluation Group Managers

From:                                       Manager, Air Transportation Division (AFS-200)

Reply to Attn of:                      Manager, New Program Implementation Branch (AFS-240)

SUBJECT:                     Automatic Dependent Surveillance-Broadcast (ADS-B)
  System

MMEL CODE:                      34 (NAVIGATION)

REFERENCE:                       PL-105, Revision 1, dated January 20, 2009
  PL-105, Original, dated October 11, 2000
  Title 14 of the Code of Federal Regulations (14 CFR) part 91, 91.225, 91.227,
  Advisory Circular (AC) 20-165, AC 20-172

PURPOSE:

The purpose of this Policy Letter is to provide standardized Master Minimum Equipment List (MMEL) requirements for Automatic Dependent Surveillance-Broadcast (ADS-B) systems.

DISCUSSION:

Revision 2: Removes the Global Change designation and replaces the previous discussion that addressed a specific ADS-B system installation with information applicable to all ADS-B installations.

The following discussion uses excerpts from the Federal Registry Docket No. FAA-2007-29305; Amdt. No. 91‑314 (14 CFR Part 91 ADS-B Out final rule), FAA AC 20-165 (guidance for ADS-B Out systems) and FAA AC 20-172 (guidance information for ADS-B In systems).

As part of NextGen development, the FAA has determined that it is essential to move from ground-based surveillance and navigation to more dynamic and accurate airborne-based systems and procedures if the agency is to enhance capacity, reduce delay, and improve environmental performance. Automatic Dependent Surveillance-Broadcast (ADS-B) equipment is an advanced surveillance technology that combines an aircraft’s positioning source, aircraft avionics, and a ground infrastructure to create an accurate surveillance interface between aircraft and air traffic control (ATC). ADS-B is a key component of NextGen that will move ATC from a radar-based system to a satellite-derived aircraft location system. ADS-B is a performance-based surveillance technology that is more precise than radar. ADS-B is expected to provide air traffic controllers and pilots with more accurate information to help keep aircraft safely separated in the sky and on runways. The technology combines a positioning capability, aircraft avionics, and ground infrastructure to enable more accurate transmission of information from aircraft to ATC.

ADS-B consists of two different functions: ADS-B Out and ADS-B In. ADS-B Out periodically broadcasts information about each aircraft, such as identification, current position, altitude, and velocity, through an onboard transmitter. ADS-B Out provides air traffic controllers with real-time position information that is, in most cases, more accurate than the information available with current radar-based systems. With more accurate information, ATC will be able to position and separate aircraft with improved precision and timing.

ADS-B In refers to an appropriately equipped aircraft’s ability to receive and display another aircraft’s ADS-B Out information, as well as the ADS-B In services provided by ground systems, including Automatic Dependent Surveillance-Rebroadcast (ADS-R), Traffic Information Service-Broadcast (TIS-B), and, if so equipped, Flight Information Service-Broadcast (FIS-B). When displayed in the cockpit, this information greatly improves the pilot’s situational awareness.

ADS-B requires a broadcast link for aircraft surveillance and to support ADS-B In applications. Operators have two options for equipage under this rule: the 1090 extended squitter (1090ES) broadcast link with performance requirements specified in TSO-C166b or the Universal Access Transceiver (UAT) broadcast link that operates on 978 MHz and has performance requirements specified in TSO-C154c.

The 1090 MHz ES broadcast link is the internationally agreed upon link for ADS-B and is intended to support ADS-B Out and ADS-B In in applications used by air carriers and other high-performance aircraft. The 1090 MHz ES broadcast link does not support FIS-B (weather and related flight information) because the bandwidth limitations of this link cannot transmit the large message structures required by FIS-B. The UAT link supports both ADS-B Out and ADS-B In, as well as FIS-B.

Beginning January 1, 2020, all aircraft operating in airspace defined in 91.225 will be required to have ADS‑B Out which meets the requirements of 91.225 and 91.227. ADS-B In will not be required.

POLICY:

The following MMEL proviso and repair interval is adopted to provide standardization among all MMELs:

MMEL TABLE KEY
SYSTEM & SEQUENCE NO.
ITEM
1. REPAIR CATEGORY
2. NUMBER INSTALLED
3. NUMBER REQUIRED FOR DISPATCH
4. REMARKS OR EXCEPTIONS

34. NAVIGATION

 

Sequence No.

Item

1

2

3

4

Change Bar

34-XX
***

Automatic Dependent Surveillance-Broadcast (ADS-B) System

C

-

0

(O) May be inoperative provided:

a)   Alternate procedures are established and used, and

b)   It is not required by 14 CFR.

NOTE: Any ADS-B function that operates normally may be used.

 

 

 

D

-

0

May be inoperative provided:

a)   Enroute operations do not require its use, and

b)   It is not required by 14 CFR.

NOTE: Any ADS-B function that operates normally may be used.

 

 

 

C

-

1

One must be operative as required by 14 CFR.

NOTE: Any ADS-B function that operates normally may be used.

 

***

ADS-B Out Extended Squitter Transmissions

C

-

0

(O) May be inoperative provided:

a)   Alternate procedures are established and used,

b)   Authorization is obtained from ATC facilities having jurisdiction over planned route of flight, and

c)   It is not required by 14 CFR.

NOTE: Any ADS-B function that operates normally may be used.

 

 

 

C

-

1

One must be operative as required by 14 CFR.

NOTE: Any ADS-B function that operates normally may be used.

 

***

ADS-B Out UAT Transmissions

C

-

0

(O) May be inoperative provided:

a)   Enroute operations do not require its use,

b)   Authorization is obtained from ATC facilities having jurisdiction over planned route of flight, and

c)   It is not required by 14 CFR.

NOTE: Any ADS-B Out function that operates normally may be used.

 

 

 

C

-

1

One must be operative as required by 14 CFR.

NOTE: Any ADS-B function that operates normally may be used

 

***

ADS-B In Transmissions

C

-

0

(O) May be inoperative provided alternate procedures are established and used.

NOTE: Any ADS-B In function that operates normally may be used.

 

 

 

D

-

0

May be inoperative provided operations do not require its use.

NOTE: Any ADS-B function that operates normally may be used.

 

Each Flight Operations Evaluation Board (FOEB) Chair should review the specific aircraft configuration(s) and apply this policy to affected MMELs through the normal FOEB process.

ORIGINAL SIGNED by

/s/ Stephen C. Moates for

Manager, Air Transportation Division