Uav pilot reports altitude deviation while on patrol. Autopilot malfunction is suggested.

Attributes
ACN	894809
Time
Date	201006
Local Time Of Day	0601-1200
Place
Locale Reference	ZAB.ARTCC
State Reference	NM
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Other
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Autopilot
Person 1
Function	Pilot Flying Single Pilot
Qualification	Flight Crew Commercial Flight Crew Flight Instructor Flight Crew Multiengine Flight Crew Instrument
Experience	Flight Crew Last 90 Days 20 Flight Crew Total 5400 Flight Crew Type 2300
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance

Narrative:

While on patrol a uav under my control experienced an altitude deviation. While flying in pre-program point and click loiter mode the aircraft climbed 900 feet when the auto pilot mode was turned off. The pilot flying turned off the altitude hold mode and recovered from the climb.

Original NASA ASRS Text

Title: UAV pilot reports altitude deviation while on patrol. Autopilot malfunction is suggested.

Narrative: While on patrol a UAV under my control experienced an altitude deviation. While flying in pre-program point and click loiter mode the aircraft climbed 900 feet when the auto pilot mode was turned off. The pilot flying turned off the altitude hold mode and recovered from the climb.

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.