A B757-200 flight crew responded to a TCAS RA with a small single engine aircraft within the washing...

Attributes
ACN	912912
Time
Date	201010
Local Time Of Day	0001-0600
Place
Locale Reference	IAD.Airport
State Reference	DC
Aircraft 1
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	Vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Small Aircraft High Wing 1 Eng Fixed Gear
Operating Under FAR Part	Part 91
Flight Plan	VFR
Person 1
Function	First Officer Pilot Not Flying
Experience	Flight Crew Last 90 Days 260 Flight Crew Total 16000 Flight Crew Type 4500
Events
Anomaly	ATC Issue All Types Conflict NMAC Deviation - Altitude Excursion From Assigned Altitude

Narrative:

At the time we were at 5;000 ft on vectors for 1C at iad under control from potomac approach. The captain and I noticed a target on TCAS that was climbing slowly through 4;000 ft headed at us. The captain prepared for a TCAS RA while the controller was talking to other aircraft. The TCAS RA told us to climb as the opposing aircraft; a single engine high wing aircraft; passed through 4;800 ft. The captain disconnected the autopilot and increased altitude to approximately 5;400 ft and I told potomac approach we were in a TCAS climb for traffic to which potomac approach said there was a VFR target within a mile and that he was not talking to him and that the altitude was unknown. The amount of separation between the small aircraft and our 757 was approx 400 ft. In fact the captain noticed that the other aircraft did reach 5;000 ft before descending back down to 4;500 ft.

Original NASA ASRS Text

Title: A B757-200 Flight Crew responded to a TCAS RA with a small single engine aircraft within the Washington Class B. ATC advised they were not in contact with the smaller aircraft.

Narrative: At the time we were at 5;000 FT on vectors for 1C at IAD under control from Potomac Approach. The Captain and I noticed a target on TCAS that was climbing slowly through 4;000 FT headed at us. The Captain prepared for a TCAS RA while the Controller was talking to other aircraft. The TCAS RA told us to CLIMB as the opposing aircraft; a single engine high wing aircraft; passed through 4;800 FT. The Captain disconnected the autopilot and increased altitude to approximately 5;400 FT and I told Potomac Approach we were in a TCAS CLIMB for traffic to which Potomac Approach said there was a VFR target within a mile and that he was not talking to him and that the altitude was unknown. The amount of separation between the small aircraft and our 757 was approx 400 FT. In fact the Captain noticed that the other aircraft did reach 5;000 FT before descending back down to 4;500 FT.

Data retrieved from NASA's ASRS site as of April 2012 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.

A B757-200 flight crew responded to a TCAS RA with a small single engine aircraft within the washington class B. ATC advised they were not in contact with the smaller aircraft.