Air carrier large transport descends below assigned altitude.

Attributes
ACN	138174
Time
Date	199002
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : lga
State Reference	NY
Altitude	msl bound lower : 6600 msl bound upper : 7000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : n90
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	descent other
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : atp pilot : cfi
Experience	flight time last 90 days : 70 flight time total : 5000
ASRS Report	138174
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	altitude deviation : overshoot non adherence : clearance non adherence : required legal separation
Independent Detector	other controllera
Resolutory Action	flight crew : returned to intended course or assigned course other
Consequence	Other
Miss Distance	horizontal : 3000 vertical : 1000
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

About 22 NM southwest of lga VOR I read back a clearance that I believe was for an altitude of 7000' MSL (reporter must mean 6000'[?]). At about 6600' the controller on north.Y. Approach on frequency 127.3 called to our attention that the altitude was 7000' MSL. There was traffic and we had him in sight and climbed back to 7000'. Supplemental information from acn 138176: thought we were cleared to descend to 6000'. Read back 'descending to 6000.' reaching 6800', controller asked if we were leveling at assigned altitude of 7000'. Replied that we were descending to 6000'. Followed his instructions to climb immediately to 7000'.

Original NASA ASRS Text

Title: ACR LGT DESCENDS BELOW ASSIGNED ALT.

Narrative: ABOUT 22 NM SW OF LGA VOR I READ BACK A CLRNC THAT I BELIEVE WAS FOR AN ALT OF 7000' MSL (RPTR MUST MEAN 6000'[?]). AT ABOUT 6600' THE CTLR ON N.Y. APCH ON FREQ 127.3 CALLED TO OUR ATTN THAT THE ALT WAS 7000' MSL. THERE WAS TFC AND WE HAD HIM IN SIGHT AND CLBED BACK TO 7000'. SUPPLEMENTAL INFO FROM ACN 138176: THOUGHT WE WERE CLRED TO DSND TO 6000'. READ BACK 'DSNDING TO 6000.' REACHING 6800', CTLR ASKED IF WE WERE LEVELING AT ASSIGNED ALT OF 7000'. REPLIED THAT WE WERE DSNDING TO 6000'. FOLLOWED HIS INSTRUCTIONS TO CLB IMMEDIATELY TO 7000'.

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.