Delayed start of descent.

Attributes
ACN	290006
Time
Date	199411
Day	Tue
Place
Locale Reference	atc facility : hec
State Reference	CA
Altitude	msl bound lower : 35000 msl bound upper : 35000
Aircraft 1
Controlling Facilities	artcc : zla
Operator	common carrier : air carrier
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 3500 flight time type : 800
ASRS Report	290006
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : undershoot non adherence : clearance other anomaly other
Independent Detector	other controllera other flight crewa
Resolutory Action	flight crew : became reoriented 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:

ZLA told us to descend from FL350 to FL280. I answered and changed the altitude window (B-757) to FL280. My company's procedure is for the PNF to change the altitude window and talk, while the PF work all other mode control panel changes (with the autoplt on). We were getting ready to do a lynxx-7 descent into bur when ATC 'interrupted' us. When I dialed in the altitude and answered ATC, I immediately went back to what I was doing -- programming the FMC for the descent, assuming the captain would initiate the descent. After a short while, the controller snapped at us to begin the descent and gave us an altitude restriction to make, which we made without a problem. I don't think there was a serious problem, but there could have been. What bothered me was that, instead of just doing what I've always done in my flying career when I'm told to descend, pulling power and descending, the FMC is now my first thought when I want to make the aircraft do something. It's wonderful most of the time, except during time critical phases of flight when it can become an attention magnet.

Original NASA ASRS Text

Title: DELAYED START OF DSCNT.

Narrative: ZLA TOLD US TO DSND FROM FL350 TO FL280. I ANSWERED AND CHANGED THE ALT WINDOW (B-757) TO FL280. MY COMPANY'S PROC IS FOR THE PNF TO CHANGE THE ALT WINDOW AND TALK, WHILE THE PF WORK ALL OTHER MODE CTL PANEL CHANGES (WITH THE AUTOPLT ON). WE WERE GETTING READY TO DO A LYNXX-7 DSCNT INTO BUR WHEN ATC 'INTERRUPTED' US. WHEN I DIALED IN THE ALT AND ANSWERED ATC, I IMMEDIATELY WENT BACK TO WHAT I WAS DOING -- PROGRAMMING THE FMC FOR THE DSCNT, ASSUMING THE CAPT WOULD INITIATE THE DSCNT. AFTER A SHORT WHILE, THE CTLR SNAPPED AT US TO BEGIN THE DSCNT AND GAVE US AN ALT RESTRICTION TO MAKE, WHICH WE MADE WITHOUT A PROB. I DON'T THINK THERE WAS A SERIOUS PROB, BUT THERE COULD HAVE BEEN. WHAT BOTHERED ME WAS THAT, INSTEAD OF JUST DOING WHAT I'VE ALWAYS DONE IN MY FLYING CAREER WHEN I'M TOLD TO DSND, PULLING PWR AND DSNDING, THE FMC IS NOW MY FIRST THOUGHT WHEN I WANT TO MAKE THE ACFT DO SOMETHING. IT'S WONDERFUL MOST OF THE TIME, EXCEPT DURING TIME CRITICAL PHASES OF FLT WHEN IT CAN BECOME AN ATTN MAGNET.

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.