Flight crew took traffic call as altitude assignment.

Attributes
ACN	282688
Time
Date	199409
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : bos
State Reference	MA
Altitude	msl bound lower : 4700 msl bound upper : 5000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : bos
Operator	common carrier : air carrier
Make Model Name	SF 340A
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent : approach
Route In Use	arrival 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 : 190 flight time total : 7000 flight time type : 2500
ASRS Report	282688
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial pilot : cfi
Experience	flight time last 90 days : 180 flight time total : 1680 flight time type : 150
ASRS Report	282687
Events
Anomaly	altitude deviation : overshoot non adherence : clearance other anomaly other
Independent Detector	other controllera other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Approach assigned 4000 ft and advise company traffic left to right be- 1900 at 4000 ft. Readback 4000 ft looking for traffic. Spotted traffic and commented, 'why did he (the controller) give us 4000 ft if company is 4000 ft, we decided to slow the descent. By this time traffic had passed and left the area. At 4700 ft, the controller said, 'confirm altitude 5000 ft' and climbed to 5000 ft. Obviously the controller wanted us at 5000 ft. Rather than debating with the controller on a congested frequency, we said, 'roger 5000 ft.' next time if we think altitudes don't make sense, we are going to ask the controller for confirmation, regardless of radio congestion.

Original NASA ASRS Text

Title: FLC TOOK TFC CALL AS ALT ASSIGNMENT.

Narrative: APCH ASSIGNED 4000 FT AND ADVISE COMPANY TFC L TO R BE- 1900 AT 4000 FT. READBACK 4000 FT LOOKING FOR TFC. SPOTTED TFC AND COMMENTED, 'WHY DID HE (THE CTLR) GIVE US 4000 FT IF COMPANY IS 4000 FT, WE DECIDED TO SLOW THE DSCNT. BY THIS TIME TFC HAD PASSED AND LEFT THE AREA. AT 4700 FT, THE CTLR SAID, 'CONFIRM ALT 5000 FT' AND CLBED TO 5000 FT. OBVIOUSLY THE CTLR WANTED US AT 5000 FT. RATHER THAN DEBATING WITH THE CTLR ON A CONGESTED FREQ, WE SAID, 'ROGER 5000 FT.' NEXT TIME IF WE THINK ALTS DON'T MAKE SENSE, WE ARE GOING TO ASK THE CTLR FOR CONFIRMATION, REGARDLESS OF RADIO CONGESTION.

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.