<< >> NASA ASRS Report 331610, March 1996

Miscom between TRACON and flight crew. Either another aircraft answered the clearance given to the flight crew or the controller thought he had given it, because reporter captain says that neither he nor his first officer heard any other clearance than what they were flying.

Attributes
ACN	331610
Time
Date	199603
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : sfo
State Reference	CA
Altitude	msl bound lower : 6000 msl bound upper : 7000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : oak tower : phl
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 20000 flight time type : 3000
ASRS Report	331610
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude other anomaly other other spatial deviation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Supplementary
Primary Problem	Ambiguous
Air Traffic Incident	other

Narrative:

Descending out of 7000 ft to 6000 ft, on a radar vector to intercept the runway 28L localizer, the approach controller called to inform us our cleared altitude was 7000 ft, not 6000 ft, and our intercept radar heading was different than we were flying. Neither the first officer nor I remember hearing or reading back any other clearance than the one we were flying. We do not have any way to determine how the event arose, whether we missed a clearance, or one was not issued as the controller thought, or the clearance was accepted by another aircraft. Both pilots distinctly remember clearance to 6000 ft.

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Original NASA ASRS Text

Title: MISCOM BTWN TRACON AND FLC. EITHER ANOTHER ACFT ANSWERED THE CLRNC GIVEN TO THE FLC OR THE CTLR THOUGHT HE HAD GIVEN IT, BECAUSE RPTR CAPT SAYS THAT NEITHER HE NOR HIS FO HEARD ANY OTHER CLRNC THAN WHAT THEY WERE FLYING.

Narrative: DSNDING OUT OF 7000 FT TO 6000 FT, ON A RADAR VECTOR TO INTERCEPT THE RWY 28L LOC, THE APCH CTLR CALLED TO INFORM US OUR CLRED ALT WAS 7000 FT, NOT 6000 FT, AND OUR INTERCEPT RADAR HDG WAS DIFFERENT THAN WE WERE FLYING. NEITHER THE FO NOR I REMEMBER HEARING OR READING BACK ANY OTHER CLRNC THAN THE ONE WE WERE FLYING. WE DO NOT HAVE ANY WAY TO DETERMINE HOW THE EVENT AROSE, WHETHER WE MISSED A CLRNC, OR ONE WAS NOT ISSUED AS THE CTLR THOUGHT, OR THE CLRNC WAS ACCEPTED BY ANOTHER ACFT. BOTH PLTS DISTINCTLY REMEMBER CLRNC TO 6000 FT.

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.