A300 flight crew has altitude excursion during cruise.

Attributes
ACN	702104
Time
Date	200607
Local Time Of Day	0001 To 0600
Place
Locale Reference	atc facility : zid.artcc
State Reference	IN
Altitude	msl bound lower : 25700 msl bound upper : 26000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zid.artcc
Operator	common carrier : air carrier
Make Model Name	A300
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
ASRS Report	702104
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	altitude deviation : undershoot non adherence : clearance
Independent Detector	other controllerb other flight crewa other flight crewb
Resolutory Action	controller : issued advisory flight crew : returned to assigned altitude
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft
Primary Problem	Flight Crew Human Performance

Narrative:

Passing 11000 ft in climb from sdf; crew heard and felt a loud bang noise in forward section of aircraft. Immediately reduced speed and maintained normal flight. Checked pressurization and all system; all system normal. While troubleshooting cause of loud noise; crew neglected to set 29.92 in altimeters. First officer was PF; and jumpseater came up to cockpit to also assist in determining cause of noise. This distraction the PF to not notice the altimeter. ATC after several mins in cruise noted that we appeared approximately 300 ft low on our altitude; and to check our altimeters. Immediately set .92 and climbed 300 ft to be level at FL260. Flight proceeded normally from that point on. Upon landing; had cargo inspected and found that a basketball size container weighing approximately 50 pounds had been left unsecured and had fallen onto the main cargo deck -- a very heavy dense object was in container.

Original NASA ASRS Text

Title: A300 FLT CREW HAS ALT EXCURSION DURING CRUISE.

Narrative: PASSING 11000 FT IN CLB FROM SDF; CREW HEARD AND FELT A LOUD BANG NOISE IN FORWARD SECTION OF ACFT. IMMEDIATELY REDUCED SPD AND MAINTAINED NORMAL FLT. CHKED PRESSURIZATION AND ALL SYS; ALL SYS NORMAL. WHILE TROUBLESHOOTING CAUSE OF LOUD NOISE; CREW NEGLECTED TO SET 29.92 IN ALTIMETERS. FO WAS PF; AND JUMPSEATER CAME UP TO COCKPIT TO ALSO ASSIST IN DETERMINING CAUSE OF NOISE. THIS DISTR THE PF TO NOT NOTICE THE ALTIMETER. ATC AFTER SEVERAL MINS IN CRUISE NOTED THAT WE APPEARED APPROX 300 FT LOW ON OUR ALT; AND TO CHK OUR ALTIMETERS. IMMEDIATELY SET .92 AND CLBED 300 FT TO BE LEVEL AT FL260. FLT PROCEEDED NORMALLY FROM THAT POINT ON. UPON LNDG; HAD CARGO INSPECTED AND FOUND THAT A BASKETBALL SIZE CONTAINER WEIGHING APPROX 50 LBS HAD BEEN LEFT UNSECURED AND HAD FALLEN ONTO THE MAIN CARGO DECK -- A VERY HVY DENSE OBJECT WAS IN CONTAINER.

Data retrieved from NASA's ASRS site as of January 2009 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.