Deviation from assigned altitude.

Attributes
ACN	201794
Time
Date	199202
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : alb
State Reference	NY
Altitude	msl bound lower : 15000 msl bound upper : 16500
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : fyv
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	cruise other
Route In Use	arrival other enroute airway : zbw enroute other
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 7500 flight time type : 2500
ASRS Report	201794
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : atp pilot : flight engineer pilot : commercial
Experience	flight time last 90 days : 180 flight time total : 16000
ASRS Report	201795
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	flight crew : exited penetrated airspace flight crew : returned to intended course or assigned course
Consequence	Other
Miss Distance	vertical : 1500
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation other

Narrative:

Flight dca to alb. We were en route at 15000 when ATC called traffic at 2 O'clock, approximately 10 NM, at 14000. We were IMC but had the traffic on TCASII. As we converged on the traffic our TCASII gave us a TA. Shortly after the vertical separation dropped below 1000 ft and we got a RA from TCASII to climb. We followed the TCASII climb command and advised ATC of our climb. We climbed to approximately 16500 before we got a clear of conflict advisory and we then returned to our assigned altitude. I do not think there ever really was a conflict, but the TCASII commands must be followed if you cannot visually confirm no conflict, I would think the problem is in the TCASII software. But as a pilot you do not know if it is that, or an altimeter error or ATC. All you can, and must do is comply with TCASII commands.

Original NASA ASRS Text

Title: DEV FROM ASSIGNED ALT.

Narrative: FLT DCA TO ALB. WE WERE ENRTE AT 15000 WHEN ATC CALLED TFC AT 2 O'CLOCK, APPROX 10 NM, AT 14000. WE WERE IMC BUT HAD THE TFC ON TCASII. AS WE CONVERGED ON THE TFC OUR TCASII GAVE US A TA. SHORTLY AFTER THE VERT SEPARATION DROPPED BELOW 1000 FT AND WE GOT A RA FROM TCASII TO CLB. WE FOLLOWED THE TCASII CLB COMMAND AND ADVISED ATC OF OUR CLB. WE CLBED TO APPROX 16500 BEFORE WE GOT A CLR OF CONFLICT ADVISORY AND WE THEN RETURNED TO OUR ASSIGNED ALT. I DO NOT THINK THERE EVER REALLY WAS A CONFLICT, BUT THE TCASII COMMANDS MUST BE FOLLOWED IF YOU CANNOT VISUALLY CONFIRM NO CONFLICT, I WOULD THINK THE PROBLEM IS IN THE TCASII SOFTWARE. BUT AS A PLT YOU DO NOT KNOW IF IT IS THAT, OR AN ALTIMETER ERROR OR ATC. ALL YOU CAN, AND MUST DO IS COMPLY WITH TCASII COMMANDS.

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.