IFR E145 has TCAS RA with VFR aircraft level 500 feet above their assigned altitude of 17000 ft MSL.

Attributes
ACN	782323
Time
Date	200804
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : gso.airport
State Reference	NC
Altitude	msl single value : 17000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc.artcc
Operator	common carrier : air carrier
Make Model Name	EMB ERJ 145 ER&LR
Operating Under FAR Part	Part 121
Flight Phase	cruise : enroute altitude change cruise : level
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zdc.artcc
Operator	general aviation : corporate
Make Model Name	Cessna Citation Undifferentiated or Other Model
Flight Phase	cruise : level
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 210 flight time total : 3800 flight time type : 3500
ASRS Report	782323
Events
Anomaly	conflict : airborne critical
Independent Detector	aircraft equipment : tcas
Resolutory Action	flight crew : took evasive action
Supplementary
Problem Areas	Airspace Structure Flight Crew Human Performance ATC Human Performance
Primary Problem	Airspace Structure

Narrative:

We were briefly leveled at 17000 ft on our way to our cruising altitude of FL260. ZDC advised us of traffic ahead at 17500 ft. I looked at the TCAS and saw a fast approaching target 500 ft above our altitude. I asked ATC to verify the altitude of the approaching traffic; and she verified 17500 ft. Before I could object; we got an RA commanding a descent. Since we didn't have visual contact with the other aircraft; I asked the first officer to immediately descend. I advised ATC that we left our altitude for an RA and she reiterated that the traffic was VFR. Shortly thereafter; we got a visual on the traffic; and once we were clear of the conflict; we re-climbed to 17000 ft. Shortly thereafter; we received a new altitude and a handoff to ZTL. The first officer and I were discussing the inadequate separation and the fast closure rate and forgot to set our altimeters to standard (the local altimeter setting had been 30.33). ZTL queried us on our altitude and we corrected the problem.

Original NASA ASRS Text

Title: IFR E145 HAS TCAS RA WITH VFR ACFT LEVEL 500 FEET ABOVE THEIR ASSIGNED ALT OF 17000 FT MSL.

Narrative: WE WERE BRIEFLY LEVELED AT 17000 FT ON OUR WAY TO OUR CRUISING ALT OF FL260. ZDC ADVISED US OF TFC AHEAD AT 17500 FT. I LOOKED AT THE TCAS AND SAW A FAST APCHING TARGET 500 FT ABOVE OUR ALT. I ASKED ATC TO VERIFY THE ALT OF THE APCHING TFC; AND SHE VERIFIED 17500 FT. BEFORE I COULD OBJECT; WE GOT AN RA COMMANDING A DSCNT. SINCE WE DIDN'T HAVE VISUAL CONTACT WITH THE OTHER ACFT; I ASKED THE FO TO IMMEDIATELY DSND. I ADVISED ATC THAT WE LEFT OUR ALT FOR AN RA AND SHE REITERATED THAT THE TFC WAS VFR. SHORTLY THEREAFTER; WE GOT A VISUAL ON THE TFC; AND ONCE WE WERE CLR OF THE CONFLICT; WE RE-CLBED TO 17000 FT. SHORTLY THEREAFTER; WE RECEIVED A NEW ALT AND A HDOF TO ZTL. THE FO AND I WERE DISCUSSING THE INADEQUATE SEPARATION AND THE FAST CLOSURE RATE AND FORGOT TO SET OUR ALTIMETERS TO STANDARD (THE LCL ALTIMETER SETTING HAD BEEN 30.33). ZTL QUERIED US ON OUR ALT AND WE CORRECTED THE PROB.

Data retrieved from NASA's ASRS site as of May 2009 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.