ARINC 545-1

W/D NO S/S * BEST COPY AVAILABLE

Purpose of this Supplement

At the time ARINC Characteristic No. 545 was finalized thealtitude reporting project was just getting under way andtherefore, not all of the basic requirements for the digitizedoutput, the protective circuitry associated with that output, andthe encoding scheme to be employed, had been completely firmed up.Furthermore, it had been expected that all air data systemmanufacturers would employ some form of disc encoder for thealtitude reporting output and thus, a specification on marginalvoltage limits for the digitized output were not deemed necessary.As the program of altitude reporting moved ahead a number of basicsystem decisions were finalized by the ICAO VII COM DivisionElectronic Engineering Committee in developing an Altitude ComputerSystem, which has now been issued as ARINC Characteristic No. 549,revealed several deficiencies in the requirements of ARINCCharacteristic No. 542.

Most of the points relating to the compatibility with ARINCCharacteristic No. 549 were discussed with equipment manufacturersduring the development of the ARINC Characteristic No. 549 documentand thus, it is believed all air data systems already provide thefeatures set forth in this Supplement. Thus, for these particularitems this Supplement will simply confirm what is now recognized asbeing desirable by the set manufacturers

With respect to the ICAO VII COM Decision decisions on analtitude encoding format, this information has previously beencirculated and is already understood by the equipmentmanufacturers.

This Supplement No. 1 will therefore reflect the changesnecessary to bring the original Characteristic No. 545 up-to-datewith respect to the ICAO decisions and to make the originalCharacteristic No. 549 with respect to the digitized altitudeoutput circuit.

Edition:

61

Published:

10/01/1961

Number of Pages:

12

File Size:

1 file , 2.5 MB