Air carrier widebody transport altitude deviation excursion from clearance altitude.

Attributes
ACN	195545
Time
Date	199111
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : lrp
State Reference	PA
Altitude	msl bound lower : 28000 msl bound upper : 28500
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zny tower : mci
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 4 Turbojet Eng
Navigation In Use	Other
Flight Phase	cruise other
Route In Use	enroute airway : j6
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : cfi pilot : commercial pilot : flight engineer
Experience	flight time last 90 days : 100 flight time total : 22500 flight time type : 40
ASRS Report	195545
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
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
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

On descent into iad, we were level at FL280. ZNY gave us a clearance to descend and cross a point 20 DME northeast of lrp VOR at and maintain FL200. The first officer read back the clearance and set the altitude alert to 20000 ft. He also went from altitude hold to altitude select which I had not called for or noticed. That step takes the autoplt out of altitude hold. As this was a descent at pilot's discretion (as long as we met our crossing restriction) and it was too far out to begin our descent, I was checking the map and reviewing the arrival. The aircraft began a gradual climb to approximately 28500 ft. The so asked what our altitude was suppose to be. I then looked at the altimeter and began an immediate correction back to FL280. Center asked what our altitude was, and we advised him that we were correcting back and beginning our descent to FL200. This could have been prevented if the confign of the autoplt, when changed, would have been announced, especially by the PNF.

Original NASA ASRS Text

Title: ACR WDB ALTDEV EXCURSION FROM CLRNC ALT.

Narrative: ON DSCNT INTO IAD, WE WERE LEVEL AT FL280. ZNY GAVE US A CLRNC TO DSND AND CROSS A POINT 20 DME NE OF LRP VOR AT AND MAINTAIN FL200. THE FO READ BACK THE CLRNC AND SET THE ALT ALERT TO 20000 FT. HE ALSO WENT FROM ALT HOLD TO ALT SELECT WHICH I HAD NOT CALLED FOR OR NOTICED. THAT STEP TAKES THE AUTOPLT OUT OF ALT HOLD. AS THIS WAS A DSCNT AT PLT'S DISCRETION (AS LONG AS WE MET OUR XING RESTRICTION) AND IT WAS TOO FAR OUT TO BEGIN OUR DSCNT, I WAS CHKING THE MAP AND REVIEWING THE ARR. THE ACFT BEGAN A GRADUAL CLB TO APPROX 28500 FT. THE SO ASKED WHAT OUR ALT WAS SUPPOSE TO BE. I THEN LOOKED AT THE ALTIMETER AND BEGAN AN IMMEDIATE CORRECTION BACK TO FL280. CENTER ASKED WHAT OUR ALT WAS, AND WE ADVISED HIM THAT WE WERE CORRECTING BACK AND BEGINNING OUR DSCNT TO FL200. THIS COULD HAVE BEEN PREVENTED IF THE CONFIGN OF THE AUTOPLT, WHEN CHANGED, WOULD HAVE BEEN ANNOUNCED, ESPECIALLY BY THE PNF.

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.