Cirrus SR22 Pilot Operating Handbook page 377

Cirrus Design
SR22 / SR22T
Hypoxia Detection and Automatic Descent (Optional)
When installed, the AFCS Hypoxia Detection and Automatic Descent
function monitors pilot inputs to the Integrated Avionics System to
identify if a pilot has become incapacitated due to hypoxia, and upon
determination, automatically descends to a lower altitude where pilot
recovery is more probable. The feature is only available when the
GFC 700 Autopilot is engaged and the aircraft is above 14,900 ft PA.
Mode of Operation
Pilot interaction with the Integrated Avionics System is monitored by
detecting key presses and turns of the knobs. If the pilot has not made
a system interaction within a defined interval - based on altitude and
time of useful consciousness - the AFCS prompts the pilot for a
response with an ARE YOU ALERT? CAS Advisory.
If no pilot response to the Advisory is detected, after one minute the
AFCS annunciates an HYPOXIA ALERT Caution and a double chime
aural alert.
After one minute, if no response to the Caution is detected the system
annunciates an AUTO DESCENT Warning and continuous aural
warning tone.
Lack of response after one minute of Warning annunciation is
considered evidence of pilot incapacitation. The AFCS will
automatically engage emergency descent mode (EDM) as follows:
1. EDM will annunciate in the AFCS status window.
2. The altitude bug will be automatically set to 14,000 ft indicated.
3. The airspeed bug will be set to the maximum commandable
Autopilot speed - i.e., the lesser of 185 KIAS or Mach 0.420.
4. The Autopilot vertical mode will change to IAS, and initiate a
descent to intercept 14,000 ft indicated.
Once descent begins only Autopilot Disconnect (AP DISC) will
interrupt this process. Autopilot lateral mode remains unchanged
throughout the descent and the aircraft will continue on its previously
selected course or heading. After reaching 14,000 ft indicated, the
aircraft will maintain this flight level for 4 additional minutes. If the pilot
does not acknowledge the Warning and resume control of the aircraft,
the AFCS will automatically perform a secondary descent to 12,500 ft
PA at 185 KIAS. An altitude of 12,500 ft PA will be maintained if the
pilot remains unresponsive
P/N 13772-135
Revision 04: 09-08-14
Section 9
Supplements
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