Small transport on test flight to check engines and pressurization descends below assigned altitude.

Attributes
ACN	245573
Time
Date	199306
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : rdu
State Reference	NC
Altitude	msl bound lower : 18000 msl bound upper : 19000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc
Operator	general aviation : corporate
Make Model Name	Small Transport, Low Wing, 2 Turboprop Eng
Navigation In Use	Other Other
Flight Phase	descent other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 4000 flight time type : 800
ASRS Report	245573
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	altitude deviation : overshoot non adherence : clearance other anomaly other
Independent Detector	other controllera 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:

Aircraft on a post maintenance check flight for pressurization and engines. Climb to FL290 and cruise uneventful. During descent, controller initially gave descent to FL260 then 13000 ft. Between FL260 and FL200 clearance was revised to FL190 and acknowledged by pilot and set into altitude alert system. Pilot continued descent and was recording engine parameters and monitoring engine, pressurization, and flight instruments. At this point pilot believed he was still cleared to 13000 ft. (Altitude alert light functioned, aural tone did not.) pilot suddenly recalled clearance revision to FL190 but by this time aircraft had descended to FL180. Pilot applied climb power and started returning to FL190 just as ATC called to confirm altitude cleared to. Contributing factors: single pilot with only visual altitude during alert (no aural). Excessive reliance on aural altitude alert system. Complex mission: trouble-shooting multiple system and recording results. Pilot distracted from task at hand. Prior clearance to a lower altitude acknowledged during a peak period of cockpit activity (i.e., not fully impressed despite entry into altitude alert system). Close in to landing site and expectations for descent were there. Poor priorities given to the tasking the pilot was encountering.

Original NASA ASRS Text

Title: SMT ON TEST FLT TO CHK ENGS AND PRESSURIZATION DSNDS BELOW ASSIGNED ALT.

Narrative: ACFT ON A POST MAINT CHK FLT FOR PRESSURIZATION AND ENGS. CLB TO FL290 AND CRUISE UNEVENTFUL. DURING DSCNT, CTLR INITIALLY GAVE DSCNT TO FL260 THEN 13000 FT. BTWN FL260 AND FL200 CLRNC WAS REVISED TO FL190 AND ACKNOWLEDGED BY PLT AND SET INTO ALT ALERT SYS. PLT CONTINUED DSCNT AND WAS RECORDING ENG PARAMETERS AND MONITORING ENG, PRESSURIZATION, AND FLT INSTS. AT THIS POINT PLT BELIEVED HE WAS STILL CLRED TO 13000 FT. (ALT ALERT LIGHT FUNCTIONED, AURAL TONE DID NOT.) PLT SUDDENLY RECALLED CLRNC REVISION TO FL190 BUT BY THIS TIME ACFT HAD DSNDED TO FL180. PLT APPLIED CLB PWR AND STARTED RETURNING TO FL190 JUST AS ATC CALLED TO CONFIRM ALT CLRED TO. CONTRIBUTING FACTORS: SINGLE PLT WITH ONLY VISUAL ALT DURING ALERT (NO AURAL). EXCESSIVE RELIANCE ON AURAL ALT ALERT SYS. COMPLEX MISSION: TROUBLE-SHOOTING MULTIPLE SYS AND RECORDING RESULTS. PLT DISTRACTED FROM TASK AT HAND. PRIOR CLRNC TO A LOWER ALT ACKNOWLEDGED DURING A PEAK PERIOD OF COCKPIT ACTIVITY (I.E., NOT FULLY IMPRESSED DESPITE ENTRY INTO ALT ALERT SYS). CLOSE IN TO LNDG SITE AND EXPECTATIONS FOR DSCNT WERE THERE. POOR PRIORITIES GIVEN TO THE TASKING THE PLT WAS ENCOUNTERING.

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.