Commuter aircraft descends below assigned altitude.

Attributes
ACN	246186
Time
Date	199307
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : tup
State Reference	MS
Altitude	msl bound lower : 5800 msl bound upper : 7000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Light Transport, Low Wing, 2 Turboprop Eng
Flight Phase	descent other
Route In Use	enroute airway : zme
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : cfi pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 150 flight time total : 3470 flight time type : 120
ASRS Report	246186
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Experience	flight time last 90 days : 280 flight time total : 2850 flight time type : 480
ASRS Report	246279
Events
Anomaly	altitude deviation : overshoot conflict : airborne less severe non adherence : clearance non adherence : required legal separation other anomaly other
Independent Detector	other controllera
Resolutory Action	flight crew : returned to intended course or assigned course other
Consequence	Other
Miss Distance	horizontal : 12000 vertical : 200
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

When descending from cruise at 8000 ft MSL to an ATC assigned altitude of 7000 ft, ATC called and asked altitude. Captain responded 5800 ft MSL and ATC gave traffic at 12 O'clock descending at 5600 ft MSL, 2 mi. During this time during the descent, the first officer was off center frequency talking on company frequency as SOP's (15 mins in-range call). SOP states 1000 ft above and 300 ft above assigned altitude calls. No altitude (selector) warning system or autoplt installed on the airplane. PF was working the radios, flying the airplane, maintaining an assigned airspeed (170 KTS). ATC assigned heading during the time the altitude deviation was encountered. The PF immediately climbed back to 7000 ft. No further action was taken. Also, during this time strong thunderstorms were in the area and we were deviating around them. Both crew members crew duty day began early at XA00 am. Already have flown 5 hours 54 mins and made 6 lndgs, 5 of which were instrument approachs.

Original NASA ASRS Text

Title: COMMUTER ACFT DSNDS BELOW ASSIGNED ALT.

Narrative: WHEN DSNDING FROM CRUISE AT 8000 FT MSL TO AN ATC ASSIGNED ALT OF 7000 FT, ATC CALLED AND ASKED ALT. CAPT RESPONDED 5800 FT MSL AND ATC GAVE TFC AT 12 O'CLOCK DSNDING AT 5600 FT MSL, 2 MI. DURING THIS TIME DURING THE DSCNT, THE FO WAS OFF CTR FREQ TALKING ON COMPANY FREQ AS SOP'S (15 MINS IN-RANGE CALL). SOP STATES 1000 FT ABOVE AND 300 FT ABOVE ASSIGNED ALT CALLS. NO ALT (SELECTOR) WARNING SYS OR AUTOPLT INSTALLED ON THE AIRPLANE. PF WAS WORKING THE RADIOS, FLYING THE AIRPLANE, MAINTAINING AN ASSIGNED AIRSPD (170 KTS). ATC ASSIGNED HDG DURING THE TIME THE ALTDEV WAS ENCOUNTERED. THE PF IMMEDIATELY CLBED BACK TO 7000 FT. NO FURTHER ACTION WAS TAKEN. ALSO, DURING THIS TIME STRONG TSTMS WERE IN THE AREA AND WE WERE DEVIATING AROUND THEM. BOTH CREW MEMBERS CREW DUTY DAY BEGAN EARLY AT XA00 AM. ALREADY HAVE FLOWN 5 HRS 54 MINS AND MADE 6 LNDGS, 5 OF WHICH WERE INST APCHS.

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.