Government navigation aid flight inspection aircraft descends below assigned altitude.

Attributes
ACN	144047
Time
Date	199004
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : hou
State Reference	TX
Altitude	msl bound lower : 23600 msl bound upper : 24000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zhu artcc : zhn
Operator	other
Make Model Name	Light Transport, Low Wing, 2 Turboprop Eng
Flight Phase	descent other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 10000
ASRS Report	144047
Person 2
Affiliation	government : faa
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:

During descent into iah for ILS flight calibration of iah ILS, the copilot was flying aircraft. The aircraft commander (PIC) in right seat was watching WX radar, setting up radios for the flight check, looking outside to see heavy thunderstorm cells and how to deviate around them. ATC clearance to descend maintain FL240. The above mentioned cockpit workload diverted the PIC's attention. The copilot descended below FL240 and the PIC caught the error as the aircraft went through FL236. Aircraft immediately leveled and climbed back to FL240. No evasive action required. Contributing factors were using non proficient coplts from flight inspection procedures section who fly about once every 4-6 weeks, deviation around heavy thunderstorm activity, cockpit workload and of flight calibration activities. To prevent further occurrence, coplts should be full time and proficient and let flight calibration duties go, even if the mission has to be terminated when all these factors require so much attention.

Original NASA ASRS Text

Title: GOVERNMENT NAVIGATION AID FLT INSPECTION ACFT DESCENDS BELOW ASSIGNED ALT.

Narrative: DURING DSNT INTO IAH FOR ILS FLT CALIBRATION OF IAH ILS, THE COPLT WAS FLYING ACFT. THE ACFT COMMANDER (PIC) IN RIGHT SEAT WAS WATCHING WX RADAR, SETTING UP RADIOS FOR THE FLT CHK, LOOKING OUTSIDE TO SEE HEAVY TSTM CELLS AND HOW TO DEVIATE AROUND THEM. ATC CLRNC TO DSND MAINTAIN FL240. THE ABOVE MENTIONED COCKPIT WORKLOAD DIVERTED THE PIC'S ATTN. THE COPLT DSNDED BELOW FL240 AND THE PIC CAUGHT THE ERROR AS THE ACFT WENT THROUGH FL236. ACFT IMMEDIATELY LEVELED AND CLBED BACK TO FL240. NO EVASIVE ACTION REQUIRED. CONTRIBUTING FACTORS WERE USING NON PROFICIENT COPLTS FROM FLT INSPECTION PROCS SECTION WHO FLY ABOUT ONCE EVERY 4-6 WKS, DEVIATION AROUND HEAVY TSTM ACTIVITY, COCKPIT WORKLOAD AND OF FLT CALIBRATION ACTIVITIES. TO PREVENT FURTHER OCCURRENCE, COPLTS SHOULD BE FULL TIME AND PROFICIENT AND LET FLT CALIBRATION DUTIES GO, EVEN IF THE MISSION HAS TO BE TERMINATED WHEN ALL THESE FACTORS REQUIRE SO MUCH ATTN.

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.