Air carrier on visual approach descends below GS and exits TCA floor.

Attributes
ACN	197311
Time
Date	199112
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : atl
State Reference	GA
Altitude	msl bound lower : 2500 msl bound upper : 3500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : atl tower : sna
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	descent : approach
Route In Use	approach : visual enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : flight engineer pilot : commercial pilot : atp
Experience	flight time last 90 days : 180 flight time total : 7500 flight time type : 1000
ASRS Report	197311
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	non adherence : far other spatial deviation
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

On approach to atl. Captain hand flying. First officer with raw data selected to comply with recent procedure change. At 3500 ft MSL approximately 10-15 southeast of atl VOR with preceding traffic in sight, ATC cleared us for visual approach. We armed approach mode so flight director would work on selected ILS frequency weights. GS captured and captain descended below 3500 ft setting off altitude alert. Since 3500 ft is published climb out altitude and we were hand flying a visual approach that is where we wanted the MCP altitude. Captain asked about a gate and I called ramp control distracting myself (my fault). On slope at approximately 2500- 2600 ft the captain and I both thought we looked low and leveled off till we reintercepted a good visual glide path. Simultaneously the ILS GS changed its weights indication and showed us low. We were on a visual and caused no conflict, but technically we descended below the TCA floor of 3500 in that area (I think). The problems: the captain hand flew and didn't monitor position/altitude versus the HSI display. The first officer (me) called for a gate instead of watching, and the first officer (me) is not accustomed to looking at raw data any more. (I've been on large transport/widebody transport for almost 2 yrs.)

Original NASA ASRS Text

Title: ACR ON VISUAL APCH DSNDS BELOW GS AND EXITS TCA FLOOR.

Narrative: ON APCH TO ATL. CAPT HAND FLYING. FO WITH RAW DATA SELECTED TO COMPLY WITH RECENT PROC CHANGE. AT 3500 FT MSL APPROX 10-15 SE OF ATL VOR WITH PRECEDING TFC IN SIGHT, ATC CLRED US FOR VISUAL APCH. WE ARMED APCH MODE SO FLT DIRECTOR WOULD WORK ON SELECTED ILS FREQ WTS. GS CAPTURED AND CAPT DSNDED BELOW 3500 FT SETTING OFF ALT ALERT. SINCE 3500 FT IS PUBLISHED CLB OUT ALT AND WE WERE HAND FLYING A VISUAL APCH THAT IS WHERE WE WANTED THE MCP ALT. CAPT ASKED ABOUT A GATE AND I CALLED RAMP CTL DISTRACTING MYSELF (MY FAULT). ON SLOPE AT APPROX 2500- 2600 FT THE CAPT AND I BOTH THOUGHT WE LOOKED LOW AND LEVELED OFF TILL WE REINTERCEPTED A GOOD VISUAL GLIDE PATH. SIMULTANEOUSLY THE ILS GS CHANGED ITS WTS INDICATION AND SHOWED US LOW. WE WERE ON A VISUAL AND CAUSED NO CONFLICT, BUT TECHNICALLY WE DSNDED BELOW THE TCA FLOOR OF 3500 IN THAT AREA (I THINK). THE PROBLEMS: THE CAPT HAND FLEW AND DIDN'T MONITOR POS/ALT VERSUS THE HSI DISPLAY. THE FO (ME) CALLED FOR A GATE INSTEAD OF WATCHING, AND THE FO (ME) IS NOT ACCUSTOMED TO LOOKING AT RAW DATA ANY MORE. (I'VE BEEN ON LGT/WDB FOR ALMOST 2 YRS.)

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.