<< >> NASA ASRS Report 338930, June 1996

A corp jet flight crew failed to meet an assigned altitude crossing restr. During the descent the crew had noticed a discrepancy in the aircraft's compass system and they were attempting to resolve the problem when ATC questioned their descent rate. The crew increased the rate, but the aircraft still crossed 3000 ft high at the restr limit.

Attributes
ACN	338930
Time
Date	199606
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : dta
State Reference	UT
Altitude	msl bound lower : 31000 msl bound upper : 34000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zlc
Operator	general aviation : corporate
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 91
Flight Phase	descent other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 100 flight time total : 5000 flight time type : 1000
ASRS Report	338930
Person 2
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Experience	flight time last 90 days : 100 flight time total : 2000 flight time type : 100
ASRS Report	338939
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : undershoot altitude deviation : crossing restriction not met non adherence : clearance
Independent Detector	other controllera
Resolutory Action	flight crew : returned to intended course or assigned course other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation other

Narrative:

ZLC advised a descent to FL310 at or prior to 15 NM south of delta. We began our descent from FL410 to be at FL310 15 NM south of delta. During the descent it was noted that there was a discrepancy in the compass system. While working the compass problem with the other pilot the descent rate began to slow. Center then queried us as to our rate. We were approaching FL348 with only 3-5 NM to go to the specified point. We then had to take actions required to increase our rate significantly to meet the restr this was undesirable since we were carrying passenger. Center advised that the reason for the descent was departing traffic from slc international. At no time was any evasive action required and no course change was necessary. Cockpit crew procedures had broken down and required more cooperation between pilots.

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Original NASA ASRS Text

Title: A CORP JET FLC FAILED TO MEET AN ASSIGNED ALT XING RESTR. DURING THE DSCNT THE CREW HAD NOTICED A DISCREPANCY IN THE ACFT'S COMPASS SYS AND THEY WERE ATTEMPTING TO RESOLVE THE PROB WHEN ATC QUESTIONED THEIR DSCNT RATE. THE CREW INCREASED THE RATE, BUT THE ACFT STILL CROSSED 3000 FT HIGH AT THE RESTR LIMIT.

Narrative: ZLC ADVISED A DSCNT TO FL310 AT OR PRIOR TO 15 NM S OF DELTA. WE BEGAN OUR DSCNT FROM FL410 TO BE AT FL310 15 NM S OF DELTA. DURING THE DSCNT IT WAS NOTED THAT THERE WAS A DISCREPANCY IN THE COMPASS SYS. WHILE WORKING THE COMPASS PROB WITH THE OTHER PLT THE DSCNT RATE BEGAN TO SLOW. CTR THEN QUERIED US AS TO OUR RATE. WE WERE APCHING FL348 WITH ONLY 3-5 NM TO GO TO THE SPECIFIED POINT. WE THEN HAD TO TAKE ACTIONS REQUIRED TO INCREASE OUR RATE SIGNIFICANTLY TO MEET THE RESTR THIS WAS UNDESIRABLE SINCE WE WERE CARRYING PAX. CTR ADVISED THAT THE REASON FOR THE DSCNT WAS DEPARTING TFC FROM SLC INTL. AT NO TIME WAS ANY EVASIVE ACTION REQUIRED AND NO COURSE CHANGE WAS NECESSARY. COCKPIT CREW PROCS HAD BROKEN DOWN AND REQUIRED MORE COOPERATION BTWN PLTS.

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.