Small aircraft off altitude due to altimeter malfunction. Aircraft equipment problem.

Attributes
ACN	307390
Time
Date	199506
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : cmh
State Reference	OH
Altitude	msl bound lower : 6600 msl bound upper : 6900
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : cmh
Operator	general aviation : personal
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Flight Phase	cruise other
Flight Plan	VFR
Aircraft 2
Make Model Name	Beechcraft Twin Turboprop Jet Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	descent other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private
Experience	flight time last 90 days : 21 flight time total : 154 flight time type : 75
ASRS Report	307390
Person 2
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	aircraft equipment problem : less severe conflict : airborne less severe non adherence : far other anomaly other
Independent Detector	other controllera
Resolutory Action	none taken : detected after the fact other
Consequence	faa : reviewed incident with flight crew Other
Miss Distance	horizontal : 2500 vertical : 300
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I was level at 6600 ft when ATC informed me of a king air descending to 7000 ft at my 11 O'clock position. I told ATC that I was looking, negative contact. I heard ATC notifying the king air. The king air came on stating that he had the traffic in sight approximately 10-15 seconds later. At the time of his transmission I spotted the king air and immediately upon his acknowledgement by ATC, reported that I too had him in sight. ATC then said to me, 'I show you at 6900 ft, what is your altitude?' I stated 6600 ft (altimeter set per ATIS 29.99). ATC then said I called you 3 times, you need to pay attention. It is my belief that they did not call 3 times as I called to notify them immediately upon the acknowledgement of the king air's sighting of me. The total time from first transmission until the call from ATC that they had called me 3 times was approximately 30-40 seconds. There was no need for evasive action on my or the king air's part. I then asked to leave the frequency to open my VFR flight plan upon which I was told to squawk 1200 and frequency change approved. I responded by asking which approach controller to call to continue flight following. Cmh ATC then said stay with me for 10 mins. I complied. After approximately 2 mins ATC said notify mansfield ATC upon return from opening your flight plan. I did so only to find that no handoff had been made and mansfield, said I should be in contact with columbus ATC. When I explained that columbus had told me to contact mansfield they assigned me another squawk code. Later I verified my altitude with toledo approach. After confirming altimeter setting and while stable at assigned altitude, they stated that their radar indicated me to be 200 ft above my altimeter reading. Upon arrival at my destination I informed the FBO owner of the discrepancy (rented aircraft) and he said he would check to confirm accuracy.

Original NASA ASRS Text

Title: SMA OFF ALT DUE TO ALTIMETER MALFUNCTION. ACFT EQUIP PROB.

Narrative: I WAS LEVEL AT 6600 FT WHEN ATC INFORMED ME OF A KING AIR DSNDING TO 7000 FT AT MY 11 O'CLOCK POS. I TOLD ATC THAT I WAS LOOKING, NEGATIVE CONTACT. I HEARD ATC NOTIFYING THE KING AIR. THE KING AIR CAME ON STATING THAT HE HAD THE TFC IN SIGHT APPROX 10-15 SECONDS LATER. AT THE TIME OF HIS XMISSION I SPOTTED THE KING AIR AND IMMEDIATELY UPON HIS ACKNOWLEDGEMENT BY ATC, RPTED THAT I TOO HAD HIM IN SIGHT. ATC THEN SAID TO ME, 'I SHOW YOU AT 6900 FT, WHAT IS YOUR ALT?' I STATED 6600 FT (ALTIMETER SET PER ATIS 29.99). ATC THEN SAID I CALLED YOU 3 TIMES, YOU NEED TO PAY ATTN. IT IS MY BELIEF THAT THEY DID NOT CALL 3 TIMES AS I CALLED TO NOTIFY THEM IMMEDIATELY UPON THE ACKNOWLEDGEMENT OF THE KING AIR'S SIGHTING OF ME. THE TOTAL TIME FROM FIRST XMISSION UNTIL THE CALL FROM ATC THAT THEY HAD CALLED ME 3 TIMES WAS APPROX 30-40 SECONDS. THERE WAS NO NEED FOR EVASIVE ACTION ON MY OR THE KING AIR'S PART. I THEN ASKED TO LEAVE THE FREQ TO OPEN MY VFR FLT PLAN UPON WHICH I WAS TOLD TO SQUAWK 1200 AND FREQ CHANGE APPROVED. I RESPONDED BY ASKING WHICH APCH CTLR TO CALL TO CONTINUE FLT FOLLOWING. CMH ATC THEN SAID STAY WITH ME FOR 10 MINS. I COMPLIED. AFTER APPROX 2 MINS ATC SAID NOTIFY MANSFIELD ATC UPON RETURN FROM OPENING YOUR FLT PLAN. I DID SO ONLY TO FIND THAT NO HDOF HAD BEEN MADE AND MANSFIELD, SAID I SHOULD BE IN CONTACT WITH COLUMBUS ATC. WHEN I EXPLAINED THAT COLUMBUS HAD TOLD ME TO CONTACT MANSFIELD THEY ASSIGNED ME ANOTHER SQUAWK CODE. LATER I VERIFIED MY ALT WITH TOLEDO APCH. AFTER CONFIRMING ALTIMETER SETTING AND WHILE STABLE AT ASSIGNED ALT, THEY STATED THAT THEIR RADAR INDICATED ME TO BE 200 FT ABOVE MY ALTIMETER READING. UPON ARR AT MY DEST I INFORMED THE FBO OWNER OF THE DISCREPANCY (RENTED ACFT) AND HE SAID HE WOULD CHK TO CONFIRM ACCURACY.

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.