Traffic given by ATC and TCASII, medium large transport flight crew climbs to avoid unknown VFR traf...

Attributes
ACN	193274
Time
Date	199110
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : mrb
State Reference	WV
Altitude	msl bound lower : 17500 msl bound upper : 18000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	climbout : intermediate altitude descent other
Route In Use	arrival other enroute airway : zdc
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Experience	flight time last 90 days : 150 flight time total : 5000 flight time type : 1500
ASRS Report	193274
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : nmac
Independent Detector	aircraft equipment other aircraft equipment : unspecified other controllera
Resolutory Action	flight crew : took evasive action other
Consequence	faa : reviewed incident with flight crew
Miss Distance	vertical : 450
Supplementary
Primary Problem	Ambiguous

Narrative:

Flight from pit-iad with jump seat rider. Normal flight to cruise FL200 to FL220. On morgontown 2 arrival approximately 50 mi from martinsburg ATC said descend to 15000. After passing 19000 ATC asked where our destination was. We said iad. Then after descending through 18000 ft ATC said level at FL180 due to VFR traffic at 17500 and by the time we acknowledged we were at 17500 and adding power. TCASII told us to monitor vertical speed as we start to climb, TCASII RA climb, climb now. We climbed back to FL180. TCASII indicated 100-500 ft. After landing the captain called the center. They said they had us confused and thought we were landing at bwi. They should have had us at 11000 at mumsy intersection, but they cleared us to 15000. We never saw the traffic, the cockpit was busy plus a little extra with a jump seat rider. TCASII helped and was very informative. We were descending 2000-2500 FPM so ATC probably had lagged information.

Original NASA ASRS Text

Title: TFC GIVEN BY ATC AND TCASII, MLG FLC CLBS TO AVOID UNKNOWN VFR TFC.

Narrative: FLT FROM PIT-IAD WITH JUMP SEAT RIDER. NORMAL FLT TO CRUISE FL200 TO FL220. ON MORGONTOWN 2 ARR APPROX 50 MI FROM MARTINSBURG ATC SAID DSND TO 15000. AFTER PASSING 19000 ATC ASKED WHERE OUR DEST WAS. WE SAID IAD. THEN AFTER DSNDING THROUGH 18000 FT ATC SAID LEVEL AT FL180 DUE TO VFR TFC AT 17500 AND BY THE TIME WE ACKNOWLEDGED WE WERE AT 17500 AND ADDING PWR. TCASII TOLD US TO MONITOR VERT SPD AS WE START TO CLB, TCASII RA CLB, CLB NOW. WE CLBED BACK TO FL180. TCASII INDICATED 100-500 FT. AFTER LNDG THE CAPT CALLED THE CENTER. THEY SAID THEY HAD US CONFUSED AND THOUGHT WE WERE LNDG AT BWI. THEY SHOULD HAVE HAD US AT 11000 AT MUMSY INTXN, BUT THEY CLRED US TO 15000. WE NEVER SAW THE TFC, THE COCKPIT WAS BUSY PLUS A LITTLE EXTRA WITH A JUMP SEAT RIDER. TCASII HELPED AND WAS VERY INFORMATIVE. WE WERE DSNDING 2000-2500 FPM SO ATC PROBABLY HAD LAGGED INFO.

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.

Traffic given by ATC and TCASII, medium large transport flight crew climbs to avoid unknown VFR traffic.