Altitude deviation on ILS approach.

Attributes
ACN	104952
Time
Date	198902
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : pit
State Reference	PA
Altitude	msl bound lower : 2600 msl bound upper : 3000
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : pit
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent : approach descent other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 28 flight time total : 20 flight time type : 0
ASRS Report	104952
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
Independent Detector	other controllera other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Captain was flying IFR ILS approach to runway 28L at pit. We were cleared for the approach to maintain 3000' until established. After localizer was captured, flight director was engaged command bars indicated descend. The captain started a descent at 2700'. I asked if he had a good G/south, about a second later approach control advised that altitude was showing 2600' and maintain 3000'. Climb was complied with to 3000'. Approach was completed to landing. This was last leg of a four day trip we were both tired, I think this was the major factor that the captain failed to realize flight director was not in the capture mode.

Original NASA ASRS Text

Title: ALT DEVIATION ON ILS APCH.

Narrative: CAPT WAS FLYING IFR ILS APCH TO RWY 28L AT PIT. WE WERE CLRED FOR THE APCH TO MAINTAIN 3000' UNTIL ESTABLISHED. AFTER LOC WAS CAPTURED, FLT DIRECTOR WAS ENGAGED COMMAND BARS INDICATED DSND. THE CAPT STARTED A DSCNT AT 2700'. I ASKED IF HE HAD A GOOD G/S, ABOUT A SECOND LATER APCH CTL ADVISED THAT ALT WAS SHOWING 2600' AND MAINTAIN 3000'. CLB WAS COMPLIED WITH TO 3000'. APCH WAS COMPLETED TO LNDG. THIS WAS LAST LEG OF A FOUR DAY TRIP WE WERE BOTH TIRED, I THINK THIS WAS THE MAJOR FACTOR THAT THE CAPT FAILED TO REALIZE FLT DIRECTOR WAS NOT IN THE CAPTURE MODE.

Data retrieved from NASA's ASRS site as of August 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.