[ACARS] More on Air Berlin oddities

[Ed Wilson]

Folks

More on the odd messages from Air Berlin aircraft

Over Christmas I was running Airmaster V3 and AirNav alongside each other. 
The signal from the Yupiteru MVT7100 was split in to two
- one feed went to an old Olivetti Pentium PC running Airmaster V3 under DOS
- the other feed went to a Toshiba 333MHz Pentium II laptop running AirNav 
ACARS decoder under Windows 98

Looking at the screen (as one does) I was astonished to see that the 'odd' 
format messages that Airmaster has been producing for over a month could be 
decoded perfectly by AirNav (sometimes AirNav would 'miss' them altogether, 
but it never showed them in the format that Airmaster used)

Below is an example: first from Airmaster; then the same message from AirNav 
- I am afraid I cannot keep all the PCs perfectly in time and synchronised! 
(as usual UTC times)

Clearly then Airmaster is, as Nick suggested, misreading the messages. But 
it must be more subtle than that as Greg showed me examples of Airmaster 
logs with uplinks and downlinks

And, as far as I am aware, this only occurs with Air Berlin aircraft. And 
when it does all messages from the aircraft are in the same 'wrong' format, 
whereas with 'ordinary' misreads then the next message from the aircraft is 
probably decoded correctly

Oddly, some Air Berlin aircraft are unaffected: and on some days aircraft 
that decoded previously correctly are wrong (not certain about vice versa)

A timing problem? Anyone any thoughts?

ACARS mode:    Aircraft reg:  G.D-AB
Message label: G   Block id: Q  Msg. no: 1 S8
Flight id: 0AAB42
Message content:-
10
-----------------------------------------------------------[25/12/2002 
05:15]

ACARS mode: G  Aircraft reg: D-ABAG
Message label: Q0  Block id: 1  Msg. no: S80A
Flight id: AB4210
-------------------------------------[25/12/2002 05:16]

Ed Wilson






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