B747-400 crew had an altitude deviation after a missed approach in IMC WX at ord.

Attributes
ACN	568060
Time
Date	200212
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : ord.airport
State Reference	IL
Altitude	msl bound lower : 5000 msl bound upper : 6500
Environment
Flight Conditions	IMC
Weather Elements	Snow
Aircraft 1
Controlling Facilities	tracon : c90.tracon
Operator	common carrier : air carrier
Make Model Name	B747-400
Operating Under FAR Part	Part 121
Flight Phase	landing : go around
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Experience	flight time type : 431
ASRS Report	568060
Person 2
Affiliation	company : air carrier
Function	flight crew : relief pilot
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Experience	flight time last 90 days : 100 flight time total : 8000 flight time type : 3325
ASRS Report	567467
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter : weather non adherence : clearance non adherence : company policies non adherence : far non adherence : published procedure other anomaly other
Independent Detector	atc equipment other atc equipment : radar other controllera other flight crewa other flight crewb
Resolutory Action	controller : issued alert flight crew : returned to assigned altitude none taken : detected after the fact
Consequence	other
Supplementary
Problem Areas	Flight Crew Human Performance Environmental Factor
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

After a go around at ord, we were level at 5000 ft. The airplane was on autoplt and the captain apparently and inexplicably hit the toga button. The aircraft started to accelerate and climb. I advised the captain that we were climbing and that we should descend. I noticed the captain struggling with the yoke, and I noticed the airplane still accelerating, so I manually reduced the throttles to idle in efforts to help him descend. ATC advised us that our mode C appeared to be malfunctioning. He showed us at 6300 ft. I told ATC that we were descending back down. Supplemental information from acn #567467: we were assigned 5000 ft after a missed approach while we were maneuvering for another try. The captain hit the go around switch, and the aircraft climbed to 6500 ft before the captain got control of the aircraft and started back down. The first officer told him to descend, but he didn't hear. At the time, he was task saturated, and was trying to do too much himself and not using his crew. Approach control reported that his mode C must be broken, because he showed us climbing through 6300 ft. Supplemental information from acn #567468: after a go around with the captain flying, we were given vectors to a different runway (runway 32R), when we were given vectors to intercept the approach. The captain hit the toga switch and ended up climbing to 6400 ft before beginning the descent for the approach. Our assigned altitude was 5000 ft when we were cleared to intercept the approach. Approach said 'check your mode C and descend.

Original NASA ASRS Text

Title: B747-400 CREW HAD AN ALTDEV AFTER A MISSED APCH IN IMC WX AT ORD.

Narrative: AFTER A GAR AT ORD, WE WERE LEVEL AT 5000 FT. THE AIRPLANE WAS ON AUTOPLT AND THE CAPT APPARENTLY AND INEXPLICABLY HIT THE TOGA BUTTON. THE ACFT STARTED TO ACCELERATE AND CLB. I ADVISED THE CAPT THAT WE WERE CLBING AND THAT WE SHOULD DSND. I NOTICED THE CAPT STRUGGLING WITH THE YOKE, AND I NOTICED THE AIRPLANE STILL ACCELERATING, SO I MANUALLY REDUCED THE THROTTLES TO IDLE IN EFFORTS TO HELP HIM DSND. ATC ADVISED US THAT OUR MODE C APPEARED TO BE MALFUNCTIONING. HE SHOWED US AT 6300 FT. I TOLD ATC THAT WE WERE DSNDING BACK DOWN. SUPPLEMENTAL INFO FROM ACN #567467: WE WERE ASSIGNED 5000 FT AFTER A MISSED APCH WHILE WE WERE MANEUVERING FOR ANOTHER TRY. THE CAPT HIT THE GAR SWITCH, AND THE ACFT CLBED TO 6500 FT BEFORE THE CAPT GOT CTL OF THE ACFT AND STARTED BACK DOWN. THE FO TOLD HIM TO DSND, BUT HE DIDN'T HEAR. AT THE TIME, HE WAS TASK SATURATED, AND WAS TRYING TO DO TOO MUCH HIMSELF AND NOT USING HIS CREW. APCH CTL RPTED THAT HIS MODE C MUST BE BROKEN, BECAUSE HE SHOWED US CLBING THROUGH 6300 FT. SUPPLEMENTAL INFO FROM ACN #567468: AFTER A GAR WITH THE CAPT FLYING, WE WERE GIVEN VECTORS TO A DIFFERENT RWY (RWY 32R), WHEN WE WERE GIVEN VECTORS TO INTERCEPT THE APCH. THE CAPT HIT THE TOGA SWITCH AND ENDED UP CLBING TO 6400 FT BEFORE BEGINNING THE DSCNT FOR THE APCH. OUR ASSIGNED ALT WAS 5000 FT WHEN WE WERE CLRED TO INTERCEPT THE APCH. APCH SAID 'CHK YOUR MODE C AND DSND.

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.