DC9-40 descended from 2500 ft to 2200 ft prematurely due to improper use of the flight director.

Attributes
ACN	353850
Time
Date	199611
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : bna
State Reference	TN
Altitude	msl bound lower : 2200 msl bound upper : 2500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : bna
Operator	common carrier : air carrier
Make Model Name	DC-9 40
Operating Under FAR Part	Part 121
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : commercial pilot : atp
Experience	flight time last 90 days : 225 flight time total : 10000 flight time type : 400
ASRS Report	353850
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	altitude deviation : excursion from assigned altitude 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:

Cleared 2500 ft until established cleared ILS runway 2C approach. Flight director vertical guidance was still in manual, even though flight director selector to ILS. Followed bars down to 2200 ft. When noticed it was not GS command, returned to 2500 ft. Approach continued normally in VMC.

Original NASA ASRS Text

Title: DC9-40 DSNDED FROM 2500 FT TO 2200 FT PREMATURELY DUE TO IMPROPER USE OF THE FLT DIRECTOR.

Narrative: CLRED 2500 FT UNTIL ESTABLISHED CLRED ILS RWY 2C APCH. FLT DIRECTOR VERT GUIDANCE WAS STILL IN MANUAL, EVEN THOUGH FLT DIRECTOR SELECTOR TO ILS. FOLLOWED BARS DOWN TO 2200 FT. WHEN NOTICED IT WAS NOT GS COMMAND, RETURNED TO 2500 FT. APCH CONTINUED NORMALLY IN VMC.

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.