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The Altitude Preselect System APS4A is intended to be used as an interface for Air Data Displays or Primary Flight Displays with alerter function, and a variety of existing Autopilot Systems to supply Altitude Preselect- and Hold-Function:
- ARC (Cessna) 400B
- ARC (Cessna) 800B
- ARC (Cessna) 1000
- Century 4
- Century 41
- Century 2000
- Collins AP106
- Bendix King KFC 200
- Bendix King KFC 250
- Bendix King KFC 300
- M4D
- S-TEC System 30
- S-TEC System 50
- S-TEC System 55
- S-TEC System 55X
- S-TEC System 60
- S-TEC System 65
