Air carrier medium large transport fails to descend to meet crossing restriction.

Attributes
ACN	132111
Time
Date	198912
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : dqo
State Reference	DE
Altitude	msl bound lower : 26000 msl bound upper : 29000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other descent other
Route In Use	arrival star : star enroute airway : j51
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 150 flight time total : 11000 flight time type : 2000
ASRS Report	132111
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : crossing restriction not met altitude deviation : undershoot non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	none taken : detected after the fact
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We were level at FL290 and received a clearance to cross 30 south of dupont at FL260. The first officer set the altitude alert to 260 and I sent a circular index mounted on my control wheel to the number 30 to indicate the mileage. At that point it is my procedure to complete the DME at which I will begin the descent. Before I could complete the computation the F/a's called with a question and the distraction was enough that I never returned to the computation. ATC called a little later and gave us an additional crossing restriction of 11,000 at somto intersection. I realized at that point we were 22 DME south of dqo and had not begun a descent. ATC never mentioned our failure to make the first crossing restriction at 30 DME. My first officer was 'out of the loop' for a few mins while he completed some required paperwork. He was therefore lost as a back-up to my performance. Human performance: this was the 3RD day of a 3-DAY trip which had report times of XX05, XY30, and XZ15. I had very little notification to fly this trip and so began with only 4 hours of sleep. Being a night person the sleep deficit built-up further as the trip went on.

Original NASA ASRS Text

Title: ACR MLG FAILS TO DESCEND TO MEET CROSSING RESTRICTION.

Narrative: WE WERE LEVEL AT FL290 AND RECEIVED A CLRNC TO CROSS 30 S OF DUPONT AT FL260. THE F/O SET THE ALT ALERT TO 260 AND I SENT A CIRCULAR INDEX MOUNTED ON MY CONTROL WHEEL TO THE NUMBER 30 TO INDICATE THE MILEAGE. AT THAT POINT IT IS MY PROC TO COMPLETE THE DME AT WHICH I WILL BEGIN THE DSCNT. BEFORE I COULD COMPLETE THE COMPUTATION THE F/A'S CALLED WITH A QUESTION AND THE DISTR WAS ENOUGH THAT I NEVER RETURNED TO THE COMPUTATION. ATC CALLED A LITTLE LATER AND GAVE US AN ADDITIONAL XING RESTRICTION OF 11,000 AT SOMTO INTXN. I REALIZED AT THAT POINT WE WERE 22 DME S OF DQO AND HAD NOT BEGUN A DSCNT. ATC NEVER MENTIONED OUR FAILURE TO MAKE THE FIRST XING RESTRICTION AT 30 DME. MY F/O WAS 'OUT OF THE LOOP' FOR A FEW MINS WHILE HE COMPLETED SOME REQUIRED PAPERWORK. HE WAS THEREFORE LOST AS A BACK-UP TO MY PERFORMANCE. HUMAN PERFORMANCE: THIS WAS THE 3RD DAY OF A 3-DAY TRIP WHICH HAD REPORT TIMES OF XX05, XY30, AND XZ15. I HAD VERY LITTLE NOTIFICATION TO FLY THIS TRIP AND SO BEGAN WITH ONLY 4 HRS OF SLEEP. BEING A NIGHT PERSON THE SLEEP DEFICIT BUILT-UP FURTHER AS THE TRIP WENT ON.

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.