Air carrier widebody transport altitude deviation crossing restriction not met.

Attributes
ACN	108107
Time
Date	198904
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : cgt
State Reference	IL
Altitude	msl bound lower : 24000 msl bound upper : 24500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zau
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	cruise other descent other
Route In Use	enroute airway : zau
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 6500 flight time type : 2000
ASRS Report	108107
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : crossing restriction not met altitude deviation : undershoot non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	none taken : anomaly accepted none taken : insufficient time
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Flight was cleared to cross 70 east of cgt at FL250. The autoplt was on operating in vertical and latitude navigation modes. The captain, PF this leg, entered the fix and altitude into the computer. As we arrived at our top of descent point, we received a new clearance to cross 70 east of cgt at FL240. After the captain re-entered the new altitude, we were high on our new vertical path, and we received a 'drag required' message. Captain intervened by increasing speed/rate of descent. The altitude arc showed that at our present rate of descent we would cross the fix at FL240. Unfortunately our rate of descent was so high that 1000-2000' prior to reaching FL240 the 'altitude capture' mode started to level the aircraft out. We subsequently crossed the fix approximately 500' above FL240. No report was made to ATC. Through my experience on the widebody transport, I should have alerted the captain, the PF, that since we were already at the top of descent point to make the crossing at FL250, we should start down immediately and modify the computer altitude's thereafter! We both should know now that when your speed and vertical descent are 'maxed out' to make a crossing allowing for no error due to level off, you're cutting it too close. Speed brakes aren't always the desirable way to hurry down, but in this case they were a must!

Original NASA ASRS Text

Title: ACR WDB ALT DEVIATION CROSSING RESTRICTION NOT MET.

Narrative: FLT WAS CLRED TO CROSS 70 E OF CGT AT FL250. THE AUTOPLT WAS ON OPERATING IN VERT AND LAT NAV MODES. THE CAPT, PF THIS LEG, ENTERED THE FIX AND ALT INTO THE COMPUTER. AS WE ARRIVED AT OUR TOP OF DSCNT POINT, WE RECEIVED A NEW CLRNC TO CROSS 70 E OF CGT AT FL240. AFTER THE CAPT RE-ENTERED THE NEW ALT, WE WERE HIGH ON OUR NEW VERT PATH, AND WE RECEIVED A 'DRAG REQUIRED' MESSAGE. CAPT INTERVENED BY INCREASING SPD/RATE OF DSCNT. THE ALT ARC SHOWED THAT AT OUR PRESENT RATE OF DSCNT WE WOULD CROSS THE FIX AT FL240. UNFORTUNATELY OUR RATE OF DSCNT WAS SO HIGH THAT 1000-2000' PRIOR TO REACHING FL240 THE 'ALT CAPTURE' MODE STARTED TO LEVEL THE ACFT OUT. WE SUBSEQUENTLY CROSSED THE FIX APPROX 500' ABOVE FL240. NO RPT WAS MADE TO ATC. THROUGH MY EXPERIENCE ON THE WDB, I SHOULD HAVE ALERTED THE CAPT, THE PF, THAT SINCE WE WERE ALREADY AT THE TOP OF DSCNT POINT TO MAKE THE XING AT FL250, WE SHOULD START DOWN IMMEDIATELY AND MODIFY THE COMPUTER ALT'S THEREAFTER! WE BOTH SHOULD KNOW NOW THAT WHEN YOUR SPD AND VERT DSCNT ARE 'MAXED OUT' TO MAKE A XING ALLOWING FOR NO ERROR DUE TO LEVEL OFF, YOU'RE CUTTING IT TOO CLOSE. SPD BRAKES AREN'T ALWAYS THE DESIRABLE WAY TO HURRY DOWN, BUT IN THIS CASE THEY WERE A MUST!

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.