A C208 autopilot failed to capture the 1;500 ft altitude select. As the aircraft approached 1;000 ft...

Attributes
ACN	925210
Time
Date	201012
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Caravan Undifferentiated
Operating Under FAR Part	Part 135
Flight Phase	Descent Initial Approach
Route In Use	Vectors
Flight Plan	IFR
Component
Aircraft Component	Altitude Hold/Capture
Person 1
Function	Pilot Flying Single Pilot
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine Flight Crew Instrument
Experience	Flight Crew Last 90 Days 156 Flight Crew Total 3597 Flight Crew Type 979
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Altitude Overshoot Deviation - Procedural Clearance Inflight Event / Encounter CFTT / CFIT

Narrative:

I had just completed a long night of cargo flights. It was in the morning on my last leg into my home base. ATC was vectoring me in for a visual approach. They had told me to descend to 1;500 ft. I had 1;500 ft put into the autopilot and it should have leveled off at that altitude. For some reason it did not and I continued down to almost 1;000 ft without noticing. At that point ATC said; 'say altitude.' I noticed my mistake; started a climb; and responded; 'correcting to 1;500 ft.' as I was climbing through 1;400 ft on [the] way back to 1;500 ft ATC gave me the altimeter setting and asked what my altitude was. I responded; 'showing 1;400 ft now.' I had become distracted with something on my phone. In combination with mild fatigue this caused me to descend through my altitude without noticing. I would like to think I would have noticed before I hit the water; but maybe not. If it were not for ATC asking about my altitude this could have been a deadly situation. This was a forceful lesson for me to keep unnecessary distractions in check while flying; especially during the non-cruise phases; and especially when fatigue may be a factor. This also was a good reminder to not become too reliant on the autopilot.

Original NASA ASRS Text

Title: A C208 autopilot failed to capture the 1;500 FT altitude select. As the aircraft approached 1;000 FT ATC asked the mildly fatigued and distracted pilot about his altitude reorienting him and possibly preventing an accident.

Narrative: I had just completed a long night of cargo flights. It was in the morning on my last leg into my home base. ATC was vectoring me in for a visual approach. They had told me to descend to 1;500 FT. I had 1;500 FT put into the autopilot and it should have leveled off at that altitude. For some reason it did not and I continued down to almost 1;000 FT without noticing. At that point ATC said; 'Say altitude.' I noticed my mistake; started a climb; and responded; 'Correcting to 1;500 FT.' As I was climbing through 1;400 FT on [the] way back to 1;500 FT ATC gave me the altimeter setting and asked what my altitude was. I responded; 'Showing 1;400 FT now.' I had become distracted with something on my phone. In combination with mild fatigue this caused me to descend through my altitude without noticing. I would like to think I would have noticed before I hit the water; but maybe not. If it were not for ATC asking about my altitude this could have been a deadly situation. This was a forceful lesson for me to keep unnecessary distractions in check while flying; especially during the non-cruise phases; and especially when fatigue may be a factor. This also was a good reminder to not become too reliant on the autopilot.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

A C208 autopilot failed to capture the 1;500 ft altitude select. As the aircraft approached 1;000 ft ATC asked the mildly fatigued and distracted pilot about his altitude reorienting him and possibly preventing an accident.