DC10 crew had an altitude deviation in ZLA class east airspace on arrival to las.

Attributes
ACN	544036
Time
Date	200204
Day	Sun
Local Time Of Day	1201 To 1800
Place
State Reference	AZ
Altitude	msl bound lower : 11000 msl bound upper : 12000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zla.artcc
Operator	common carrier : air carrier
Make Model Name	DC-10 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : second officer
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 150 flight time total : 7000 flight time type : 3000
ASRS Report	544036
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	aircraft equipment problem : critical altitude deviation : excursion from assigned altitude other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to assigned altitude none taken : detected after the fact
Consequence	other
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft Company
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

As the so on a flight from ZZZ-las, we were on vectors for the arrival into las. The aircraft had been acting up. We lost a generator and the autoplt (#2) had lost altitude on several occasions. I was attempting to get arrival information and contacting company to give inbound information when we were on vectors from ATC at 12000 ft. Suddenly, I noticed that we were descending and the captain made mention that we should be at 12000 ft as we were descending to 11000 ft. The captain and copilot switched to autoplt #1 and selected vertical speed back to 12000 ft. The rest of the flight was without incident. This could have occurred without some breakdown in crew coordination, ATC, and aircraft system degradation. Since both pilot and copilot haven't flown in a while, I should have paid more attention to the route flown. At our company, so's are not given commercial chart approach plates.

Original NASA ASRS Text

Title: DC10 CREW HAD AN ALTDEV IN ZLA CLASS E AIRSPACE ON ARR TO LAS.

Narrative: AS THE SO ON A FLT FROM ZZZ-LAS, WE WERE ON VECTORS FOR THE ARR INTO LAS. THE ACFT HAD BEEN ACTING UP. WE LOST A GENERATOR AND THE AUTOPLT (#2) HAD LOST ALT ON SEVERAL OCCASIONS. I WAS ATTEMPTING TO GET ARR INFO AND CONTACTING COMPANY TO GIVE INBOUND INFO WHEN WE WERE ON VECTORS FROM ATC AT 12000 FT. SUDDENLY, I NOTICED THAT WE WERE DSNDING AND THE CAPT MADE MENTION THAT WE SHOULD BE AT 12000 FT AS WE WERE DSNDING TO 11000 FT. THE CAPT AND COPLT SWITCHED TO AUTOPLT #1 AND SELECTED VERT SPD BACK TO 12000 FT. THE REST OF THE FLT WAS WITHOUT INCIDENT. THIS COULD HAVE OCCURRED WITHOUT SOME BREAKDOWN IN CREW COORD, ATC, AND ACFT SYS DEGRADATION. SINCE BOTH PLT AND COPLT HAVEN'T FLOWN IN A WHILE, I SHOULD HAVE PAID MORE ATTN TO THE RTE FLOWN. AT OUR COMPANY, SO'S ARE NOT GIVEN COMMERCIAL CHART APCH PLATES.

Data retrieved from NASA's ASRS site as of July 2007 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.