E145 crew 300 ft off assigned altitude had not noticed a logbook entry describing an altitude encode...

Attributes
ACN	561236
Time
Date	200209
Day	Sun
Local Time Of Day	0601 To 1200
Place
State Reference	OH
Altitude	msl bound lower : 15000 msl bound upper : 15300
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zid.artcc
Operator	common carrier : air carrier
Make Model Name	EMB ERJ 145 ER&LR
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zid.artcc
Operator	common carrier : air carrier
Make Model Name	Do 328 TP (Turboprop)
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 3900 flight time type : 1000
ASRS Report	561236
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne less severe maintenance problem : non compliance with mel non adherence : required legal separation
Independent Detector	atc equipment other atc equipment : radar/mode c aircraft equipment : tcas other controllera other flight crewa
Resolutory Action	controller : issued advisory flight crew : returned to assigned altitude other
Miss Distance	horizontal : 300 vertical : 700
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

On initial contact with ZID, our flight was assigned to climb to 15000 ft MSL. We were then given crossing TA's for a DO328 crossing at 16000 ft. We leveled at 15000 ft roughly 10 mi from the target at 16000 ft. Shortly thereafter, we were queried by ATC 'verify level at 15000 ft' which we verified. After a few seconds pause, the other aircraft queried ATC as to our altitude, apparently as a result of a TCASII TA. He indicated that to him it appeared as if we were level at 15300 ft. ATC then asked us to check our altimeter and once again verify altitude as 15000 ft because he also showed our altitude readout as 300 ft high! We had the crossing traffic in sight and reported as such and also verified our altimeter setting and altitude at 15000 ft. The traffic passed without incident. We noted the altitude encoder discrepancy in the aircraft maintenance log and took appropriate MEL procedures at our destination.

Original NASA ASRS Text

Title: E145 CREW 300 FT OFF ASSIGNED ALT HAD NOT NOTICED A LOGBOOK ENTRY DESCRIBING AN ALT ENCODER PROB.

Narrative: ON INITIAL CONTACT WITH ZID, OUR FLT WAS ASSIGNED TO CLB TO 15000 FT MSL. WE WERE THEN GIVEN XING TA'S FOR A DO328 XING AT 16000 FT. WE LEVELED AT 15000 FT ROUGHLY 10 MI FROM THE TARGET AT 16000 FT. SHORTLY THEREAFTER, WE WERE QUERIED BY ATC 'VERIFY LEVEL AT 15000 FT' WHICH WE VERIFIED. AFTER A FEW SECONDS PAUSE, THE OTHER ACFT QUERIED ATC AS TO OUR ALT, APPARENTLY AS A RESULT OF A TCASII TA. HE INDICATED THAT TO HIM IT APPEARED AS IF WE WERE LEVEL AT 15300 FT. ATC THEN ASKED US TO CHK OUR ALTIMETER AND ONCE AGAIN VERIFY ALT AS 15000 FT BECAUSE HE ALSO SHOWED OUR ALT READOUT AS 300 FT HIGH! WE HAD THE XING TFC IN SIGHT AND RPTED AS SUCH AND ALSO VERIFIED OUR ALTIMETER SETTING AND ALT AT 15000 FT. THE TFC PASSED WITHOUT INCIDENT. WE NOTED THE ALT ENCODER DISCREPANCY IN THE ACFT MAINT LOG AND TOOK APPROPRIATE MEL PROCS AT OUR DEST.

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.

E145 crew 300 ft off assigned altitude had not noticed a logbook entry describing an altitude encoder problem.