While in the arrival phase approaching sea, flight crew believes clearance to descend to 5000 ft was...

Attributes
ACN	403966
Time
Date	199806
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : sea
State Reference	WA
Altitude	msl bound lower : 6000 msl bound upper : 7000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : sea
Operator	common carrier : air carrier
Make Model Name	Dash 8-100
Operating Under FAR Part	Part 121
Flight Phase	cruise other descent other
Route In Use	arrival other arrival star : star enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air taxi
Make Model Name	S-76/S-76 Mark II
Operating Under FAR Part	Part 135
Flight Phase	climbout : intermediate altitude cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : commercial pilot : atp
Experience	flight time last 90 days : 202 flight time total : 7886 flight time type : 1981
ASRS Report	403966
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : commercial pilot : instrument
Experience	flight time last 90 days : 187 flight time total : 5210 flight time type : 594
ASRS Report	404509
Events
Anomaly	conflict : airborne less severe other anomaly other
Independent Detector	atc equipment other atc equipment : unspecified other controllera other flight crewa
Resolutory Action	controller : issued new clearance flight crew : returned to intended course or assigned course other
Consequence	Other
Miss Distance	horizontal : 3500 vertical : 700
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

We were flying the jawbn 5 arrival inbound from diggn. The first officer transmitted a readback of a descent and turn clearance which I had not heard as being directed at us. During his readback, I heard him state a heading of 150 degrees but I remember the altitude as being garbled for some reason. I may have had the #2 communication switched to company frequency. The autoplt was engaged. I moved the heading bug to 150 degrees and asked him to confirm the assigned altitude. He advised we were cleared to 5000 ft and I set the altitude preselect to 5000 ft and commenced a descent at 1000 FPM. Several mins later, we noticed traffic ahead on a close to reciprocal heading below us -- range approximately 3-5 mi and I think the TCASII showed about 600 ft below us. Very shortly after this (perhaps 2 seconds), sea approach asked us to climb immediately to 7000 ft. I disengaged the autoplt, added power and transitioned from a descent to a climb, leveling at 7000 ft. Just after initiating the climb, the TCASII gave us an RA to 'climb.' as I was leveling off through about 6700-6800 ft for 7000 ft, the advisory changed to 'monitor vertical speed.' it may have been below this altitude -- events happened rather quickly. Once level at 7000 ft, the first officer replied that he had given a readback of 5000 ft. The controller advised that she had not heard that. I don't know if she meant she had not heard any readback or just the altitude portion or something altogether different. The first officer was absolutely certain of his readback of 5000 ft and had showed no hesitation when I had asked him earlier to confirm the altitude. Supplemental information from acn 404509: contributing factors: condition of headset below average, causing high cockpit noise level to be a mild distraction. Intercom between pilots had to be turned up high. Congested airspace. Nonstandard vector profile on approach to sea.

Original NASA ASRS Text

Title: WHILE IN THE ARR PHASE APCHING SEA, FLC BELIEVES CLRNC TO DSND TO 5000 FT WAS ISSUED BY THE CTLR. AFTER CREW RECEIVED A TCASII TA AND AN RA, THE CTLR ADVISED CLRNC TO 7000 FT HAD BEEN ISSUED.

Narrative: WE WERE FLYING THE JAWBN 5 ARR INBOUND FROM DIGGN. THE FO XMITTED A READBACK OF A DSCNT AND TURN CLRNC WHICH I HAD NOT HEARD AS BEING DIRECTED AT US. DURING HIS READBACK, I HEARD HIM STATE A HDG OF 150 DEGS BUT I REMEMBER THE ALT AS BEING GARBLED FOR SOME REASON. I MAY HAVE HAD THE #2 COM SWITCHED TO COMPANY FREQ. THE AUTOPLT WAS ENGAGED. I MOVED THE HDG BUG TO 150 DEGS AND ASKED HIM TO CONFIRM THE ASSIGNED ALT. HE ADVISED WE WERE CLRED TO 5000 FT AND I SET THE ALT PRESELECT TO 5000 FT AND COMMENCED A DSCNT AT 1000 FPM. SEVERAL MINS LATER, WE NOTICED TFC AHEAD ON A CLOSE TO RECIPROCAL HDG BELOW US -- RANGE APPROX 3-5 MI AND I THINK THE TCASII SHOWED ABOUT 600 FT BELOW US. VERY SHORTLY AFTER THIS (PERHAPS 2 SECONDS), SEA APCH ASKED US TO CLB IMMEDIATELY TO 7000 FT. I DISENGAGED THE AUTOPLT, ADDED PWR AND TRANSITIONED FROM A DSCNT TO A CLB, LEVELING AT 7000 FT. JUST AFTER INITIATING THE CLB, THE TCASII GAVE US AN RA TO 'CLB.' AS I WAS LEVELING OFF THROUGH ABOUT 6700-6800 FT FOR 7000 FT, THE ADVISORY CHANGED TO 'MONITOR VERT SPD.' IT MAY HAVE BEEN BELOW THIS ALT -- EVENTS HAPPENED RATHER QUICKLY. ONCE LEVEL AT 7000 FT, THE FO REPLIED THAT HE HAD GIVEN A READBACK OF 5000 FT. THE CTLR ADVISED THAT SHE HAD NOT HEARD THAT. I DON'T KNOW IF SHE MEANT SHE HAD NOT HEARD ANY READBACK OR JUST THE ALT PORTION OR SOMETHING ALTOGETHER DIFFERENT. THE FO WAS ABSOLUTELY CERTAIN OF HIS READBACK OF 5000 FT AND HAD SHOWED NO HESITATION WHEN I HAD ASKED HIM EARLIER TO CONFIRM THE ALT. SUPPLEMENTAL INFO FROM ACN 404509: CONTRIBUTING FACTORS: CONDITION OF HEADSET BELOW AVERAGE, CAUSING HIGH COCKPIT NOISE LEVEL TO BE A MILD DISTR. INTERCOM BTWN PLTS HAD TO BE TURNED UP HIGH. CONGESTED AIRSPACE. NONSTANDARD VECTOR PROFILE ON APCH TO SEA.

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.

While in the arrival phase approaching sea, flight crew believes clearance to descend to 5000 ft was issued by the controller. After crew received a TCASII TA and an RA, the controller advised clearance to 7000 ft had been issued.