An A320 entered a 'thrust lock' condition during a go around after toga was not selected. This confu...

Narrative:

Altitude deviation of about 500 ft occurred when the autothrust system went into thrust lock in the toga position. We climbed from 2000-2500 ft. We were in level flight being vectored back around for another approach after performing a go around due to an aircraft on the runway (he was in position and holding; but would not respond to tower's repeated attempts to clear him for takeoff). The go around was not initiated by positioning thrust levers to toga; rather an open climb was selected to 2000 ft. We began the go around from about 1200-1300 ft AGL. However; within about 15 seconds of initiating the go around; the captain did select toga briefly; then returned the thrust levers to the climb detent. This did not put it into srs and ground trk mode however; and we still had the landing memos displayed on the upper ECAM. That is why another attempt was made to go to toga (briefly; then return to climb detent) while in level flight. But it does not explain how or why the autothrust went to thrust lock while at toga position. It seems that maybe the autothrust somehow disconnected when the levers were not toga. In any case the event caused a flap overspd alert and the gain of 500 ft. Autothrust and autoplt were disconnected. We did reactivate and confirm the approach. It was after that when things returned to normal. Autoplt and autothrust were re-engaged; and we completed a normal landing. ATC made no mention of the altitude deviation. The flap overspd was written up. The captain explained that it didn't make sense to go to toga to climb about 700-800 ft; and that is why he flew it the way he did (very smooth by the way). And he did go to toga momentarily to get it into the go around mode; but it didn't happen. We agreed that maybe he didn't leave the thrust levers in the toga position long enough for the FMGC to recognize it. Still; it doesn't explain the thrust lock at toga that we got later on; but I can't help but think that not using toga initially had something to do with it. I will remember this episode the next time I do a go around whether I'm PF or pm. Always start a go around with toga; even if it is only momentarily as the manual suggests (when initiating above 1000 ft AGL).

Original NASA ASRS Text

Title: AN A320 ENTERED A 'THRUST LOCK' CONDITION DURING A GO AROUND AFTER TOGA WAS NOT SELECTED. THIS CONFUSED THE CREW AS THE ACFT OVERSPED THE FLAPS AND CLB 500 FT HIGH.

Narrative: ALTDEV OF ABOUT 500 FT OCCURRED WHEN THE AUTOTHRUST SYS WENT INTO THRUST LOCK IN THE TOGA POS. WE CLBED FROM 2000-2500 FT. WE WERE IN LEVEL FLT BEING VECTORED BACK AROUND FOR ANOTHER APCH AFTER PERFORMING A GAR DUE TO AN ACFT ON THE RWY (HE WAS IN POS AND HOLDING; BUT WOULD NOT RESPOND TO TWR'S REPEATED ATTEMPTS TO CLR HIM FOR TKOF). THE GAR WAS NOT INITIATED BY POSITIONING THRUST LEVERS TO TOGA; RATHER AN OPEN CLB WAS SELECTED TO 2000 FT. WE BEGAN THE GAR FROM ABOUT 1200-1300 FT AGL. HOWEVER; WITHIN ABOUT 15 SECONDS OF INITIATING THE GAR; THE CAPT DID SELECT TOGA BRIEFLY; THEN RETURNED THE THRUST LEVERS TO THE CLB DETENT. THIS DID NOT PUT IT INTO SRS AND GND TRK MODE HOWEVER; AND WE STILL HAD THE LNDG MEMOS DISPLAYED ON THE UPPER ECAM. THAT IS WHY ANOTHER ATTEMPT WAS MADE TO GO TO TOGA (BRIEFLY; THEN RETURN TO CLB DETENT) WHILE IN LEVEL FLT. BUT IT DOES NOT EXPLAIN HOW OR WHY THE AUTOTHRUST WENT TO THRUST LOCK WHILE AT TOGA POS. IT SEEMS THAT MAYBE THE AUTOTHRUST SOMEHOW DISCONNECTED WHEN THE LEVERS WERE NOT TOGA. IN ANY CASE THE EVENT CAUSED A FLAP OVERSPD ALERT AND THE GAIN OF 500 FT. AUTOTHRUST AND AUTOPLT WERE DISCONNECTED. WE DID REACTIVATE AND CONFIRM THE APCH. IT WAS AFTER THAT WHEN THINGS RETURNED TO NORMAL. AUTOPLT AND AUTOTHRUST WERE RE-ENGAGED; AND WE COMPLETED A NORMAL LNDG. ATC MADE NO MENTION OF THE ALTDEV. THE FLAP OVERSPD WAS WRITTEN UP. THE CAPT EXPLAINED THAT IT DIDN'T MAKE SENSE TO GO TO TOGA TO CLB ABOUT 700-800 FT; AND THAT IS WHY HE FLEW IT THE WAY HE DID (VERY SMOOTH BY THE WAY). AND HE DID GO TO TOGA MOMENTARILY TO GET IT INTO THE GAR MODE; BUT IT DIDN'T HAPPEN. WE AGREED THAT MAYBE HE DIDN'T LEAVE THE THRUST LEVERS IN THE TOGA POS LONG ENOUGH FOR THE FMGC TO RECOGNIZE IT. STILL; IT DOESN'T EXPLAIN THE THRUST LOCK AT TOGA THAT WE GOT LATER ON; BUT I CAN'T HELP BUT THINK THAT NOT USING TOGA INITIALLY HAD SOMETHING TO DO WITH IT. I WILL REMEMBER THIS EPISODE THE NEXT TIME I DO A GAR WHETHER I'M PF OR PM. ALWAYS START A GAR WITH TOGA; EVEN IF IT IS ONLY MOMENTARILY AS THE MANUAL SUGGESTS (WHEN INITIATING ABOVE 1000 FT AGL).

Data retrieved from NASA's ASRS site as of May 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.

Attributes
ACN	804661
Time
Date	200809
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl bound lower : 2000 msl bound upper : 2500
Environment
Flight Conditions	VMC
Aircraft 1
Controlling Facilities	tracon : zzz.tracon tower : zzz.tower
Operator	common carrier : air carrier
Make Model Name	A320
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : approach landing : go around
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
ASRS Report	804661
Events
Anomaly	altitude deviation : overshoot non adherence : company policies non adherence : published procedure other anomaly
Independent Detector	other flight crewa
Resolutory Action	flight crew : overrode automation flight crew : regained aircraft control
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

An A320 entered a 'thrust lock' condition during a go around after toga was not selected. This confused the crew as the aircraft oversped the flaps and climb 500 ft high.