A B727 flight crew descended below the assigned altitude near atl.

Attributes
ACN	453789
Time
Date	199910
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : atl.airport
State Reference	GA
Altitude	msl bound lower : 11600 msl bound upper : 12000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : atl.tracon
Operator	common carrier : air carrier
Make Model Name	B727-200
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude descent : approach
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 15000 flight time type : 300
ASRS Report	453789
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 6500 flight time type : 1500
ASRS Report	453790
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	other flight crewa other flight crewb other other : 3
Resolutory Action	flight crew : returned to assigned altitude
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We were on a vector by approach and the autoplt was flying (but has no automatic leveloff capability). We were cleared to 12000 ft and during the leveloff we were given a runway change. Our attention was momentarily shifted to the runway and approach preparation. In the meantime, the aircraft descended to 11600 ft. We all saw this about the same time and we climbed back up to 12000 ft. I believe the problem to be we all became distraction by the runway change at a critical time. Supplemental information from acn 453790: I was flying. We were given a heading change and runway change so I looked down to find approach plate. Bottom line: I chose to search for approach plate at a critical time when I should have waited and done this support work with autoplt on altitude hold.

Original NASA ASRS Text

Title: A B727 FLC DSNDED BELOW THE ASSIGNED ALT NEAR ATL.

Narrative: WE WERE ON A VECTOR BY APCH AND THE AUTOPLT WAS FLYING (BUT HAS NO AUTO LEVELOFF CAPABILITY). WE WERE CLRED TO 12000 FT AND DURING THE LEVELOFF WE WERE GIVEN A RWY CHANGE. OUR ATTN WAS MOMENTARILY SHIFTED TO THE RWY AND APCH PREPARATION. IN THE MEANTIME, THE ACFT DSNDED TO 11600 FT. WE ALL SAW THIS ABOUT THE SAME TIME AND WE CLBED BACK UP TO 12000 FT. I BELIEVE THE PROB TO BE WE ALL BECAME DISTR BY THE RWY CHANGE AT A CRITICAL TIME. SUPPLEMENTAL INFO FROM ACN 453790: I WAS FLYING. WE WERE GIVEN A HDG CHANGE AND RWY CHANGE SO I LOOKED DOWN TO FIND APCH PLATE. BOTTOM LINE: I CHOSE TO SEARCH FOR APCH PLATE AT A CRITICAL TIME WHEN I SHOULD HAVE WAITED AND DONE THIS SUPPORT WORK WITH AUTOPLT ON ALT HOLD.

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.