Maastricht-UAC/EDYY ATN only as of August
 

Dear EDYY Data Link community,

as of 24.08.2021, MUAC will provide CPDLC via FANS B+/ATN only – legacy FANS 1/A will seize as of then!
(in line with the rest of the continental European ANSPs) and practically be replaced by the new FANS-C,
with ADS-C capability supporting 4D initial trajectory sharing (EPP).

WIE all NM Log-On listed dual stack airframes, shall LOG-ON via ATN to EDYY (iso FANS 1/A)
appropriate dual stack avionics configuration/cockpit shall be adapted WIE to smoothen the transition.

Aircraft not yet LO listed, but eligible for LOG ON listing, shall provide their details please according:
https://ext.eurocontrol.int/WikiLink...php/Logon_List.

Take care and Safe flights! Rational:
FANS1/A is not covered by the EU Data Link Service Implementing Rule 29/2009 nor supported by any other ANSP in central EU airspace.
ever designed for high-density airspace, mostly neither meeting DLS-IR integrity nor latency requirements (e.g. via ACAS with only 2.4 Kbits/Sec),
the natural phase out of FANS 1/A legacy aircraft has also been accelerated due to fleet modernizations following the COVID-19 pandemic.

Generating less than 15% of the Data Link traffic, FANS 1/A contributed unfortunately to more than 80% of the issues,
often not resolvable due to major FMS design flaws like missing DM99 or the proceed to … via … UL79, missing the essential via part.

Technical mitigations at MUAC became increasingly complicated, lacking effectiveness, such as the implementation of the Maximum Up Link timer
which failed after more than 3 year lead in preparation, as 50% of the aircraft still do not, and probably will never support this important functionality,
more than 2 decades after introduction.

Also in the cockpit FANS 1/A crews had increasing problems, reporting a too high succession of ULs, 6 ULs in 2 Min.
(technical and operational messages), being too much in such a slow system, and contributing to loosing situational awareness.

Generating growing ATN compatibility issues, FANS 1/A was never ATCO’s first Data link choice. Not capable of supporting the main DL incentive,
o increase capacity in high traffic loads, justification for continuing FANS 1/A support became difficult.

After 8 years of excluding bad performing ATN avionics through a laborious Log On Listing process (150% Provider Abort rate in 250 CPDLC hours in 4 month),
we can no longer justify to continue to support even worse performing FANS 1/A aircraft.

We consider that as a whole MUAC will benefit more from focusing its efforts on ATN and the next generation of CPDLC, ramping up for base line ADS-C 2 trajectory downlink operations. Our objective remains to enhance Data Link performance at MUAC, especially when higher traffic loads will demand performant
and reliable CPDLC operations, for the benefit of ATCOs and pilots alike.

happy landings!
(and LOG ON EDYY)

Another nail in the coffin of Single European Sky . Here we are in 2021 , not having ben able to enforce a Data link standard , more than 25 years after its development! And all those wonderful tools SESAR is promising will not work without a proper data link. I am glad I am retired ..

Not quite, actually the opposite as (slow) FANS 1/A was neither supported by any continental ANSP, nor mandated by the DLS-IR 29/2009
(nor designed for high density airspace). As a mater of the fact MUAC is now finally concentrating on ATN only, which has reached 75% equipage,
while the natural outflow of remaining legacy FANS 1/A only aircraft is accelerating following the pandemic. SES concentrating on ATN while
Base Line 2 with EPP sharing is now around the corner.

In our ACC we have both FANS & ATN equipped aircraft coming through. The difference is really quite large. FANS performance is very poor, very slow, sometimes just doesn't work at all. It's not reliable for our purposes. So much so we are prohibbited for using it for level change.
On the other hand ATN works a treat. It would be great if all aircraft were mandated ATN only, so this is probably good news for the single european sky effort.