Wrong transponder code.

Attributes
ACN	122507
Time
Date	198909
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : ord
State Reference	IL
Altitude	msl bound lower : 3000 msl bound upper : 3000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : ord tracon : bld
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 3 Turbojet Eng
Navigation In Use	Other
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : commercial pilot : instrument
Experience	flight time last 90 days : 150 flight time total : 18000 flight time type : 700
ASRS Report	122507
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	non adherence : far other anomaly other
Independent Detector	other controllera
Resolutory Action	other other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Ord approach controller questioned our transponder code about 8 mi out on visibility approach to runway 9L at ord. I looked and saw code XXXX set instead of our original discrete code. First officer said he had reset code to XXXX when we were cleared for visibility approach. I was involved with flying the approach and looking for traffic, and did not see him reach down and change code. This was my first trip with this first officer, but I was surprised at his confusion about transponder settings, as this is a common occurrence to accept a visibility approach on an IFR flight plan. We discussed his action after landing.

Original NASA ASRS Text

Title: WRONG TRANSPONDER CODE.

Narrative: ORD APCH CTLR QUESTIONED OUR XPONDER CODE ABOUT 8 MI OUT ON VIS APCH TO RWY 9L AT ORD. I LOOKED AND SAW CODE XXXX SET INSTEAD OF OUR ORIGINAL DISCRETE CODE. F/O SAID HE HAD RESET CODE TO XXXX WHEN WE WERE CLRED FOR VIS APCH. I WAS INVOLVED WITH FLYING THE APCH AND LOOKING FOR TFC, AND DID NOT SEE HIM REACH DOWN AND CHANGE CODE. THIS WAS MY FIRST TRIP WITH THIS F/O, BUT I WAS SURPRISED AT HIS CONFUSION ABOUT XPONDER SETTINGS, AS THIS IS A COMMON OCCURRENCE TO ACCEPT A VIS APCH ON AN IFR FLT PLAN. WE DISCUSSED HIS ACTION AFTER LNDG.

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