Medium large transport flight crew descends below assigned altitude on a STAR. Error caught quickly.

Attributes
ACN	335150
Time
Date	199605
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : iah
State Reference	TX
Altitude	msl bound lower : 9800 msl bound upper : 10000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zhu tower : dca
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	descent other
Route In Use	arrival star : star
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 9000 flight time type : 1800
ASRS Report	335150
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : overshoot non adherence : clearance
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:

We were cleared to cross hoagi at 10000 ft. Approaching hoagi I called 11000 ft. The first officer acknowledged and decreased the rate of descent. Passing 10500 ft with 2 mi to go to hoagi, we were given a frequency change and clearance. While I was reading back and looking down to put in the frequency the first officer descended below 10000 ft. I saw this at 9900 ft, but the first officer had already caught it and was returning to 10000 ft. The lowest the altimeter read was 9800 ft. Both altimeters and the altitude alerter were set correctly at 30.00 inches. I let myself become distracted with the new clearance and frequency right at level off and missed the descent through the assigned altitude.

Original NASA ASRS Text

Title: MLG FLC DSNDS BELOW ASSIGNED ALT ON A STAR. ERROR CAUGHT QUICKLY.

Narrative: WE WERE CLRED TO CROSS HOAGI AT 10000 FT. APCHING HOAGI I CALLED 11000 FT. THE FO ACKNOWLEDGED AND DECREASED THE RATE OF DSCNT. PASSING 10500 FT WITH 2 MI TO GO TO HOAGI, WE WERE GIVEN A FREQ CHANGE AND CLRNC. WHILE I WAS READING BACK AND LOOKING DOWN TO PUT IN THE FREQ THE FO DSNDED BELOW 10000 FT. I SAW THIS AT 9900 FT, BUT THE FO HAD ALREADY CAUGHT IT AND WAS RETURNING TO 10000 FT. THE LOWEST THE ALTIMETER READ WAS 9800 FT. BOTH ALTIMETERS AND THE ALT ALERTER WERE SET CORRECTLY AT 30.00 INCHES. I LET MYSELF BECOME DISTRACTED WITH THE NEW CLRNC AND FREQ RIGHT AT LEVEL OFF AND MISSED THE DSCNT THROUGH THE ASSIGNED ALT.

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.