An air carrier B737-200 leaves its assigned altitude while the first officer PNF is off on a company...

Attributes
ACN	417210
Time
Date	199810
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : mia
State Reference	FL
Altitude	msl bound lower : 14500 msl bound upper : 16000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zma tracon : mia tower : bgm
Operator	common carrier : air carrier
Make Model Name	B737-200
Operating Under FAR Part	Part 121
Flight Phase	descent other
Route In Use	arrival other enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : instrument pilot : commercial
Experience	flight time last 90 days : 200 flight time total : 5400 flight time type : 1400
ASRS Report	417210
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance non adherence other other anomaly other
Independent Detector	other flight crewa
Resolutory Action	controller : issued new clearance
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

While switching from ZMA to mia approach, PF descended to 12000 ft from (assigned) 16000 ft after radio handoff and directive to slow to 210 KTS and turn to heading 120 degrees. PNF did not hear the 12000 ft assignment, and queried PF, who stopped descent at 14500 ft. No conflict arose, in VFR conditions, and we were shortly cleared down to 8000 ft by approach for an uneventful landing in mia. PNF was contacting company on different frequency, and was unaware of PF deviation from assigned altitude. (No traffic anywhere near us, just think confusion arose from 'all those twos,' ie, heading 120 degrees and airspeed 210 KTS.)

Original NASA ASRS Text

Title: AN ACR B737-200 LEAVES ITS ASSIGNED ALT WHILE THE FO PNF IS OFF ON A COMPANY CALL.

Narrative: WHILE SWITCHING FROM ZMA TO MIA APCH, PF DSNDED TO 12000 FT FROM (ASSIGNED) 16000 FT AFTER RADIO HDOF AND DIRECTIVE TO SLOW TO 210 KTS AND TURN TO HDG 120 DEGS. PNF DID NOT HEAR THE 12000 FT ASSIGNMENT, AND QUERIED PF, WHO STOPPED DSCNT AT 14500 FT. NO CONFLICT AROSE, IN VFR CONDITIONS, AND WE WERE SHORTLY CLRED DOWN TO 8000 FT BY APCH FOR AN UNEVENTFUL LNDG IN MIA. PNF WAS CONTACTING COMPANY ON DIFFERENT FREQ, AND WAS UNAWARE OF PF DEV FROM ASSIGNED ALT. (NO TFC ANYWHERE NEAR US, JUST THINK CONFUSION AROSE FROM 'ALL THOSE TWOS,' IE, HDG 120 DEGS AND AIRSPD 210 KTS.)

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.

An air carrier B737-200 leaves its assigned altitude while the first officer PNF is off on a company call.