This SAE Aerospace Recommended Practice (ARP) provides performance criteria for Altitude Alerting Devices and Systems. These devices can be self-contained or receive remote altitude information and can have integral or remote barometric corrections. Only the generation of the alerting signals is covered by this recommended practice and not the details of the visual or audio alerts operated by these signals. It is recommended that the system's operational correspondence between the selected altitude settings of the Altitude Alerting Device and the Altitude Level Indication normally used to control the aircraft should not exceed ±250 ft RSS throughout the operating range of the device.
Range of Altitude:
This recommended practice provides for operational performance up to 80,000 ft of altitude based on pressure altitude, radar altitude or radio altitude in any combination or singular inputs.
This device should contain or accept inputs of altitude, equal to that information displayed and used by the pilot for height control of his aircraft, in increments of not greater than 100 ft of indicated altitude. This device should provide for audio/visual warning signals when the flight altitude deviates from the preselect altitude or height level and for approaching and/or departing a preselect altitude level.
The following is a listing of other parameter inputs which can augment and modify the altitude alerting system in its operation at various levels of flight altitude and landing approach altitudes.
a. Altitude Rate of Change
b. Angle of Attack
c. Radio Altitude
d. Airspeed Minimum/Maximum
e. Mach Number Minimum/Maximum
f. Flap Position
g. Landing Gear Position
h. Minimum Decision Height
1. Cat. II Series
2. Cat. III Series
i. Auto Land System
j. Automatic Flight Control and Stability Augmentation Systems
k. Altitude Function Inputs via a C.A.D.C. System
l. Altitude Rate of Change via INS System
This ARP establishes an industry recommended practice for altitude warning devices and systems, when used as an alerting device related to altitude information normally used for aircraft height control, but not including the remote sources of such information.