Mq-9 pilot reports a programming error that results in a 1;000 ft altitude deviation before it's det...

Attributes
ACN	1076083
Time
Date	201303
Local Time Of Day	1801-2400
Place
Locale Reference	DUG.Airport
State Reference	AZ
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Make Model Name	UAV - Unpiloted Aerial Vehicle
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	Direct
Flight Plan	IFR
Component
Aircraft Component	Autopilot
Person 1
Function	Pilot Flying Single Pilot
Qualification	Flight Crew Commercial Flight Crew Flight Instructor Flight Crew Instrument Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 75 Flight Crew Total 2200 Flight Crew Type 500
Events
Anomaly	Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance

Narrative:

While operating an mq-9 unmanned aircraft system; I was level as assigned by center at FL190. I designed a pre-program mission to allow the aircraft to loiter over a surveillance target. While designing the mission I mistakenly allowed the first waypoint of that mission to be left at its default altitude of 6;000 MSL. After giving the aircraft autopilot the instruction to fly the mission I immediately noticed its decreasing altitude. I immediately disabled the autopilot resulting in only a minimal altitude loss. I corrected the design of the operational mission; and thought that I sent it to the aircraft. However during that time I became distracted with a handover brief to another pilot. Before getting out of the seat to handover to the relief pilot I activated pre-program for the autopilot again. After trading seats I looked back at the altitude display to see that the aircraft had descended over 1;000 ft. The relief pilot saw it at the same time and commanded the aircraft to arrest its descent and climb back to FL190. The center controller contacted the aircrew to notify them of the altitude loss and the aircrew informed the controller that the aircraft was returning to its assigned altitude.

Original NASA ASRS Text

Title: MQ-9 pilot reports a programming error that results in a 1;000 FT altitude deviation before it's detected and corrected.

Narrative: While operating an MQ-9 Unmanned aircraft system; I was level as assigned by Center at FL190. I designed a pre-program mission to allow the aircraft to loiter over a surveillance target. While designing the mission I mistakenly allowed the first waypoint of that mission to be left at its default altitude of 6;000 MSL. After giving the aircraft autopilot the instruction to fly the mission I immediately noticed its decreasing altitude. I immediately disabled the autopilot resulting in only a minimal altitude loss. I corrected the design of the operational mission; and thought that I sent it to the aircraft. However during that time I became distracted with a handover brief to another pilot. Before getting out of the seat to handover to the Relief Pilot I activated pre-program for the autopilot again. After trading seats I looked back at the altitude display to see that the aircraft had descended over 1;000 FT. The Relief Pilot saw it at the same time and commanded the aircraft to arrest its descent and climb back to FL190. The Center Controller contacted the aircrew to notify them of the altitude loss and the aircrew informed the Controller that the aircraft was returning to its assigned altitude.

Data retrieved from NASA's ASRS site as of July 2013 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.

Mq-9 pilot reports a programming error that results in a 1;000 ft altitude deviation before it's detected and corrected.