During an instrument training flight the wrong altimeter setting was made causing a low altitude readout to ATC. In addition, the mode C altitude readout seems to differ to that of the aircraft altimeter in some instances according to ATC feedback.

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Attributes
ACN	350960
Time
Date	199610
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : svm airport : fnt
State Reference	MI
Altitude	msl bound lower : 4700 msl bound upper : 5000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : dtw
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	IFR
Person 1
Affiliation	Other
Function	instruction : instructor
Qualification	other other : other pilot : commercial pilot : instrument pilot : cfi
Experience	flight time last 90 days : 45 flight time total : 1300 flight time type : 700
ASRS Report	350960
Person 2
Affiliation	Other
Function	instruction : trainee
Qualification	pilot : private
Events
Anomaly	aircraft equipment problem : less severe other anomaly other
Independent Detector	other controllera
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Flint departure just handed us off to detroit approach, who gave us a new altimeter setting, which was noticeably higher than flint's. We reset the altimeter and adjusted our altitude. We understood the new setting to be 30.37. Soon, detroit advised us that we were 300 ft low, and told us that the correct altimeter was 30.27. Even after resetting to 30.27, we were still advised of being 100-200 ft low, but soon were told we were at the assigned altitude (5000 ft). Previously, flint had no problem with our altitude readout. Detroit said that maybe the difference was due to colder temperatures in our location. In the future I will clarify any altimeter setting that doesn't initially seem right. Also, I will request periodic mode C checks while airborne.

Original NASA ASRS Text

Title: DURING AN INST TRAINING FLT THE WRONG ALTIMETER SETTING WAS MADE CAUSING A LOW ALT READOUT TO ATC. IN ADDITION, THE MODE C ALT READOUT SEEMS TO DIFFER TO THAT OF THE ACFT ALTIMETER IN SOME INSTANCES ACCORDING TO ATC FEEDBACK.

Narrative: FLINT DEP JUST HANDED US OFF TO DETROIT APCH, WHO GAVE US A NEW ALTIMETER SETTING, WHICH WAS NOTICEABLY HIGHER THAN FLINT'S. WE RESET THE ALTIMETER AND ADJUSTED OUR ALT. WE UNDERSTOOD THE NEW SETTING TO BE 30.37. SOON, DETROIT ADVISED US THAT WE WERE 300 FT LOW, AND TOLD US THAT THE CORRECT ALTIMETER WAS 30.27. EVEN AFTER RESETTING TO 30.27, WE WERE STILL ADVISED OF BEING 100-200 FT LOW, BUT SOON WERE TOLD WE WERE AT THE ASSIGNED ALT (5000 FT). PREVIOUSLY, FLINT HAD NO PROB WITH OUR ALT READOUT. DETROIT SAID THAT MAYBE THE DIFFERENCE WAS DUE TO COLDER TEMPS IN OUR LOCATION. IN THE FUTURE I WILL CLARIFY ANY ALTIMETER SETTING THAT DOESN'T INITIALLY SEEM RIGHT. ALSO, I WILL REQUEST PERIODIC MODE C CHKS WHILE AIRBORNE.

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.