C9 crew had an altitude excursion in ZLA class east airspace.

Attributes
ACN	511470
Time
Date	200105
Day	Tue
Place
Locale Reference	airport : njk.airport
State Reference	CA
Altitude	msl bound lower : 7000 msl bound upper : 9000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	other
Make Model Name	DC-9 Undifferentiated or Other Model
Flight Phase	descent : intermediate altitude
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zla.artcc
Operator	other
Make Model Name	Hiller Helicopter, Undifferentiated or Other Model
Flight Phase	cruise : level
Person 1
Affiliation	government : military
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : multi engine pilot : commercial pilot : atp
Experience	flight time last 90 days : 58 flight time total : 4700 flight time type : 1192
ASRS Report	511470
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance non adherence : published procedure non adherence : far other anomaly other
Resolutory Action	controller : issued new clearance controller : issued alert none taken : detected after the fact
Miss Distance	horizontal : 24000 vertical : 0
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation other

Narrative:

Inbound and descending to el centro, ca (njk), I called the field in sight while on a vector to gwire to our cleared altitude of 9000 ft. I was told to continue on the vector. After passing gwire and about to enter mexican airspace, I asked center if we could turn and again we had the field in sight. They cleared us direct el centro (clearance originally to imperial) but no altitude was given. They also gave us a traffic call. I called traffic and field in sight and my copilot clicked off the autoplt and headed for the field descending. We both assumed we were cleared for the visual approach. Passing 7000 ft, center asked what altitude we were at. I replied passing 7000 ft. They said our last assigned was 9000 ft, gave me a number to call, then cleared us for the visual. A combination of wanting and expecting the visual, having the traffic in sight, and the field, then getting an amended clearance that didn't include an altitude set, us up for thinking we were cleared for something we wanted and expected.

Original NASA ASRS Text

Title: C9 CREW HAD AN ALT EXCURSION IN ZLA CLASS E AIRSPACE.

Narrative: INBOUND AND DSNDING TO EL CENTRO, CA (NJK), I CALLED THE FIELD IN SIGHT WHILE ON A VECTOR TO GWIRE TO OUR CLRED ALT OF 9000 FT. I WAS TOLD TO CONTINUE ON THE VECTOR. AFTER PASSING GWIRE AND ABOUT TO ENTER MEXICAN AIRSPACE, I ASKED CTR IF WE COULD TURN AND AGAIN WE HAD THE FIELD IN SIGHT. THEY CLRED US DIRECT EL CENTRO (CLRNC ORIGINALLY TO IMPERIAL) BUT NO ALT WAS GIVEN. THEY ALSO GAVE US A TFC CALL. I CALLED TFC AND FIELD IN SIGHT AND MY COPLT CLICKED OFF THE AUTOPLT AND HEADED FOR THE FIELD DSNDING. WE BOTH ASSUMED WE WERE CLRED FOR THE VISUAL APCH. PASSING 7000 FT, CTR ASKED WHAT ALT WE WERE AT. I REPLIED PASSING 7000 FT. THEY SAID OUR LAST ASSIGNED WAS 9000 FT, GAVE ME A NUMBER TO CALL, THEN CLRED US FOR THE VISUAL. A COMBINATION OF WANTING AND EXPECTING THE VISUAL, HAVING THE TFC IN SIGHT, AND THE FIELD, THEN GETTING AN AMENDED CLRNC THAT DIDN'T INCLUDE AN ALT SET, US UP FOR THINKING WE WERE CLRED FOR SOMETHING WE WANTED AND EXPECTED.

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.