Altitude bust. Clearance interpretation.

Attributes
ACN	274606
Time
Date	199406
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : sea
State Reference	WA
Altitude	msl bound lower : 9000 msl bound upper : 13000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zse
Operator	general aviation : corporate
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 91
Flight Phase	climbout : intermediate altitude cruise 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 : 10200 flight time type : 500
ASRS Report	274606
Person 2
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : cfi pilot : atp
Experience	flight time last 90 days : 120 flight time total : 7500 flight time type : 500
ASRS Report	274605
Events
Anomaly	altitude deviation : overshoot conflict : airborne less severe non adherence : clearance non adherence : required legal separation other anomaly other
Independent Detector	other controllera
Resolutory Action	none taken : detected after the fact
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 27000 vertical : 1000
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I, as PF, heard 130 thinking this to mean we were cleared to 13000 ft. Along with this clearance was a frequency change. I climbed to 13000 ft and discovered from next controller that we were at wrong altitude. Due to frequency congestion, pilot/copilot workload, copilot did not notice my error. To add to the confusion there was an 'ab' on frequency, our call sign was 'ba.' pilot/copilot need to verify altitude changes and this is normally our SOP. Pilot/copilot coordination will be looked at in our operation very closely. Supplemental information from acn 274605: copilot read back to departure controller the assigned heading of 130 degrees, climb to 9000 ft. Pilot heard 130 and thought that to be the altitude cleared to. At the same time the copilot was getting charts out for letdown into pdx, and switching frequency to ZSE. Copilot did not notice climb to 13000 ft. ZSE advised of error to us. Called them on phone. They told me of 4.5 separation -- not enough. Copilot and pilot need to verify what the other is doing.

Original NASA ASRS Text

Title: ALT BUST. CLRNC INTERP.

Narrative: I, AS PF, HEARD 130 THINKING THIS TO MEAN WE WERE CLRED TO 13000 FT. ALONG WITH THIS CLRNC WAS A FREQ CHANGE. I CLBED TO 13000 FT AND DISCOVERED FROM NEXT CTLR THAT WE WERE AT WRONG ALT. DUE TO FREQ CONGESTION, PLT/COPLT WORKLOAD, COPLT DID NOT NOTICE MY ERROR. TO ADD TO THE CONFUSION THERE WAS AN 'AB' ON FREQ, OUR CALL SIGN WAS 'BA.' PLT/COPLT NEED TO VERIFY ALT CHANGES AND THIS IS NORMALLY OUR SOP. PLT/COPLT COORD WILL BE LOOKED AT IN OUR OP VERY CLOSELY. SUPPLEMENTAL INFO FROM ACN 274605: COPLT READ BACK TO DEP CTLR THE ASSIGNED HDG OF 130 DEGS, CLB TO 9000 FT. PLT HEARD 130 AND THOUGHT THAT TO BE THE ALT CLRED TO. AT THE SAME TIME THE COPLT WAS GETTING CHARTS OUT FOR LETDOWN INTO PDX, AND SWITCHING FREQ TO ZSE. COPLT DID NOT NOTICE CLB TO 13000 FT. ZSE ADVISED OF ERROR TO US. CALLED THEM ON PHONE. THEY TOLD ME OF 4.5 SEPARATION -- NOT ENOUGH. COPLT AND PLT NEED TO VERIFY WHAT THE OTHER IS DOING.

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.