Altitude deviation altitude excursion.

Attributes
ACN	314690
Time
Date	199509
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : oak
State Reference	CA
Altitude	msl bound lower : 8500 msl bound upper : 9000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : oak
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 : approach descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : atp
Experience	flight time last 90 days : 210 flight time total : 15000 flight time type : 500
ASRS Report	314690
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 170 flight time total : 7000 flight time type : 1100
ASRS Report	314691
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance non adherence other other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	controller : issued new clearance flight crew : became reoriented none taken : anomaly accepted
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

While being radar vectored for an approach to oak the PF (captain) was handling ATC, while PNF (first officer) was doing a PA to the passenger. Some communication was confused or misunderstood and the assigned altitude was uncertain. 9000 ft was set on the altitude alerter, but the PF understood that 7000 ft was the last assigned altitude. We had descended to 8500 ft before a discussion between the PF and PNF regarding the last assigned altitude was. It was determined to request confirmation. No immediate response was received from ATC. We were finally given 8000 ft with no comments made. As a result, we do not know if any excursion or deviation was made. ATC was very busy and was giving speed, altitudes, heading, traffic and clrncs quite rapidly. I can understand and appreciate their workload, however too much information, too fast, is not a good combination as confusion and misinterpretation can be introduced. Overall, I feel that ATC does a commendable job under their circumstances. Supplemental information from acn 314691: I thought we were cleared to 7000 ft, slow to 180 KTS. I slowed the airplane, while leveling off at approximately 9000 ft. The first officer did not hear descend to 7000 ft, so the altitude alerter was set at 9000 ft. I then started to descend to 7000 ft and the alerter went off. I leveled off at 8500 ft and climbed back up to 9000 ft. I asked the first officer to verify we were cleared to 7000 ft. He asked approach what our clearance altitude was (twice). ATC then responded, 'air carrier X descend to 8000 ft, we have traffic behind you at 7000 ft.'

Original NASA ASRS Text

Title: ALT DEV ALT EXCURSION.

Narrative: WHILE BEING RADAR VECTORED FOR AN APCH TO OAK THE PF (CAPT) WAS HANDLING ATC, WHILE PNF (FO) WAS DOING A PA TO THE PAX. SOME COM WAS CONFUSED OR MISUNDERSTOOD AND THE ASSIGNED ALT WAS UNCERTAIN. 9000 FT WAS SET ON THE ALT ALERTER, BUT THE PF UNDERSTOOD THAT 7000 FT WAS THE LAST ASSIGNED ALT. WE HAD DSNDED TO 8500 FT BEFORE A DISCUSSION BTWN THE PF AND PNF REGARDING THE LAST ASSIGNED ALT WAS. IT WAS DETERMINED TO REQUEST CONFIRMATION. NO IMMEDIATE RESPONSE WAS RECEIVED FROM ATC. WE WERE FINALLY GIVEN 8000 FT WITH NO COMMENTS MADE. AS A RESULT, WE DO NOT KNOW IF ANY EXCURSION OR DEV WAS MADE. ATC WAS VERY BUSY AND WAS GIVING SPD, ALTS, HDG, TFC AND CLRNCS QUITE RAPIDLY. I CAN UNDERSTAND AND APPRECIATE THEIR WORKLOAD, HOWEVER TOO MUCH INFO, TOO FAST, IS NOT A GOOD COMBINATION AS CONFUSION AND MISINTERPRETATION CAN BE INTRODUCED. OVERALL, I FEEL THAT ATC DOES A COMMENDABLE JOB UNDER THEIR CIRCUMSTANCES. SUPPLEMENTAL INFO FROM ACN 314691: I THOUGHT WE WERE CLRED TO 7000 FT, SLOW TO 180 KTS. I SLOWED THE AIRPLANE, WHILE LEVELING OFF AT APPROX 9000 FT. THE FO DID NOT HEAR DSND TO 7000 FT, SO THE ALT ALERTER WAS SET AT 9000 FT. I THEN STARTED TO DSND TO 7000 FT AND THE ALERTER WENT OFF. I LEVELED OFF AT 8500 FT AND CLBED BACK UP TO 9000 FT. I ASKED THE FO TO VERIFY WE WERE CLRED TO 7000 FT. HE ASKED APCH WHAT OUR CLRNC ALT WAS (TWICE). ATC THEN RESPONDED, 'ACR X DSND TO 8000 FT, WE HAVE TFC BEHIND YOU AT 7000 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.