BAE4100 descends below crossing restr altitude on arrival to iad.

Attributes
ACN	452880
Time
Date	199910
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	intersection : hyper
State Reference	VA
Altitude	msl bound lower : 8500 msl bound upper : 9000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : iad.tracon
Operator	common carrier : air carrier
Make Model Name	Jetstream 41
Operating Under FAR Part	Part 121
Flight Phase	descent : approach descent : intermediate altitude descent : vacating altitude
Route In Use	arrival : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : cfi pilot : commercial
Experience	flight time last 90 days : 180 flight time total : 2100 flight time type : 900
ASRS Report	452880
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : overshoot altitude deviation : crossing restriction not met non adherence : far non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	controller : issued alert flight crew : returned to original clearance
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Ewr direct iad, night, clear, traffic intensity 5 out of 10. Instructions: cross hyper intersection at 9000 ft and then cross robert intersection at 8000 ft. I set up the FMS to cross hyper at 9000 ft and the captain set the altitude selector to 8000 ft but adjusted the rate of descent in excess of the required to cross hyper at 9000 ft, causing us to descend below 9000 ft prior to hyper. He thought the instructions were at or below and made a change to the descent rate after I verified the appropriate descent rate, which was originally input. ATC queried us at 8500 ft and we climbed back up to cross hyper at 9000 ft. I should have watched the captain closer, but he did have the FMS set right the first time. He should have let me know of the new change.

Original NASA ASRS Text

Title: BAE4100 DSNDS BELOW XING RESTR ALT ON ARR TO IAD.

Narrative: EWR DIRECT IAD, NIGHT, CLR, TFC INTENSITY 5 OUT OF 10. INSTRUCTIONS: CROSS HYPER INTXN AT 9000 FT AND THEN CROSS ROBERT INTXN AT 8000 FT. I SET UP THE FMS TO CROSS HYPER AT 9000 FT AND THE CAPT SET THE ALT SELECTOR TO 8000 FT BUT ADJUSTED THE RATE OF DSCNT IN EXCESS OF THE REQUIRED TO CROSS HYPER AT 9000 FT, CAUSING US TO DSND BELOW 9000 FT PRIOR TO HYPER. HE THOUGHT THE INSTRUCTIONS WERE AT OR BELOW AND MADE A CHANGE TO THE DSCNT RATE AFTER I VERIFIED THE APPROPRIATE DSCNT RATE, WHICH WAS ORIGINALLY INPUT. ATC QUERIED US AT 8500 FT AND WE CLBED BACK UP TO CROSS HYPER AT 9000 FT. I SHOULD HAVE WATCHED THE CAPT CLOSER, BUT HE DID HAVE THE FMS SET RIGHT THE FIRST TIME. HE SHOULD HAVE LET ME KNOW OF THE NEW CHANGE.

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.