Flight crew of an A300 descended and turned inbound prematurely on approach transition to runway 5R ...

Attributes
ACN	579730
Time
Date	200304
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : mmmx.airport
State Reference	FO
Altitude	msl single value : 9300
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	tower : mmmx.tower
Operator	common carrier : air carrier
Make Model Name	A300
Operating Under FAR Part	Part 121
Navigation In Use	ils localizer & glide slope : 5r other
Flight Phase	descent : approach
Route In Use	approach : instrument precision
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	579730
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
ASRS Report	579733
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : published procedure non adherence : clearance non adherence : company policies non adherence : far other anomaly other anomaly other spatial deviation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance controller : issued advisory flight crew : regained aircraft control flight crew : returned to intended or assigned course flight crew : became reoriented flight crew : overcame equipment problem
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We were on the 160 degree radial smo, approximately 5 DME, and cleared for the approach ILS DME 2, runway 5R, mex. I was the PF. The autoplt clicked off just as the first officer was changing frequencys from approach to tower. I reached up and reengaged the #1 autoplt. We had already checked radios and EFIS. The aircraft started a left turn. I thought it was to intercept the localizer, so started the descent to 8800 ft MSL. I looked at the display to see if 'localizer' appeared. I did not see it. I could see buildings down off my left and then looked at my navigation display to see we were off course to the left. I stopped the descent at around 9300 ft MSL and started back to the right when tower controller asked about our position. He said we were left of course. We asked for a vector to intercept the localizer for runway 5R. He asked if we had ground contact and also if we had the airport in sight. We said we had ground contact, but not the airport at that time, so he gave us a heading to intercept the localizer and was ok with the altitude we were holding. We completed the approach and landed. I could have detected this premature turn earlier if I had briefed the turn radial 248 degrees and had the first officer on raw data. Next time, I will definitely brief that and be ready for the unexpected. I don't know why the autoplt clicked off.

Original NASA ASRS Text

Title: FLT CREW OF AN A300 DSNDED AND TURNED INBOUND PREMATURELY ON APCH TRANSITION TO RWY 5R AT MEX.

Narrative: WE WERE ON THE 160 DEG RADIAL SMO, APPROX 5 DME, AND CLRED FOR THE APCH ILS DME 2, RWY 5R, MEX. I WAS THE PF. THE AUTOPLT CLICKED OFF JUST AS THE FO WAS CHANGING FREQS FROM APCH TO TWR. I REACHED UP AND REENGAGED THE #1 AUTOPLT. WE HAD ALREADY CHKED RADIOS AND EFIS. THE ACFT STARTED A L TURN. I THOUGHT IT WAS TO INTERCEPT THE LOC, SO STARTED THE DSCNT TO 8800 FT MSL. I LOOKED AT THE DISPLAY TO SEE IF 'LOC' APPEARED. I DID NOT SEE IT. I COULD SEE BUILDINGS DOWN OFF MY L AND THEN LOOKED AT MY NAV DISPLAY TO SEE WE WERE OFF COURSE TO THE L. I STOPPED THE DSCNT AT AROUND 9300 FT MSL AND STARTED BACK TO THE R WHEN TWR CTLR ASKED ABOUT OUR POS. HE SAID WE WERE L OF COURSE. WE ASKED FOR A VECTOR TO INTERCEPT THE LOC FOR RWY 5R. HE ASKED IF WE HAD GND CONTACT AND ALSO IF WE HAD THE ARPT IN SIGHT. WE SAID WE HAD GND CONTACT, BUT NOT THE ARPT AT THAT TIME, SO HE GAVE US A HEADING TO INTERCEPT THE LOC AND WAS OK WITH THE ALT WE WERE HOLDING. WE COMPLETED THE APCH AND LANDED. I COULD HAVE DETECTED THIS PREMATURE TURN EARLIER IF I HAD BRIEFED THE TURN RADIAL 248 DEGS AND HAD THE FO ON RAW DATA. NEXT TIME, I WILL DEFINITELY BRIEF THAT AND BE READY FOR THE UNEXPECTED. I DON'T KNOW WHY THE AUTOPLT CLICKED OFF.

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.

Flight crew of an A300 descended and turned inbound prematurely on approach transition to runway 5R at mex.