ACMS data over ACARS

By Staffan Elmén, SAS

ACMS is an acronym for Aircraft Condition Monitoring System. This consists of a computer related to the Flight Recorder - also called the "Black Box" (though its colour is orange!). Parameters from various aircraft systems are acquired and available for processing. Typical parameters are: aircraft speed, altitude, position, heading, engine rotor speeds, temperatures and various pressures etc. In a modern aircraft like Boeing 767 and Boeing 737 there are more than 1000 parameters available!

ACMS has been widely used in SAS for many years, but output facilities have been limited to magnetic tape- or optical recordings and sometimes to a cockpit printer. This has been - and remains to be - a valuable tool for e.g. trouble-shooting, flight analysis and selecting data for engine trend/health monitoring.

So, with the introduction of datalink, we are now able to get the data from an aircraft in flight! If there is a need for certain aircraft data, we are able to get it on a PC in a couple of minutes! In all honesty, however, only a small subset of all the parameters – just a snapshot - are downlinked and cannot replace the huge amount of parameters recorded every second on the magnetic tape or optical disk.

The ACMS software is able to automatically downlink data at predefined parameter limit exceedances if for example a technical malfunction would occur. It is, however, also possible to get data on request from the ground.

To summarize, whenever maintenance actions are necessary, the possibility of having access to ACMS-data in real-time by means of ACARS datalink is a valuable asset.

The MD-80 fleet is being equipped with a Mini-ACMS function, embedded as an application on the Rockwell-Collins DLM-900 and CMU-900 ACARS/VDL-2 units. It provides basic ACMS data via ACARS without installation of dedicated ACMS equipment.

See also the related page on MET Data

Example of an ACMS report:

041,AC-REG,B737-600,860122,SK9999,EKCH.,ESSA.,1084,SK6003::13.17.5
7,CR,4903,39012,236,.77,-51.8,-25.8,N5758.7,E01601.7,46821::084.7,084
.7,090.7,090.6,597.0,596.7,002.5,002.2::00908,00904,0060,0060,41,42,1
03,104::0.40,1.29,0.41,2.04,0.04,0.16,0.22,0.17::013,305,040,343::110
0000011,51::018CE,018CE,00000,00000,00009,00009::

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