While giving IMC orientation to student, instructor pilot descends through assigned altitude.

Attributes
ACN	436658
Time
Date	199905
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : mli.airport
State Reference	IL
Altitude	msl bound lower : 2500 msl bound upper : 4000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : mli.tracon
Operator	general aviation : instructional
Make Model Name	Skyhawk 172/Cutlass 172
Flight Phase	cruise : enroute altitude change
Flight Plan	IFR Combined VFR
Person 1
Affiliation	other
Function	instruction : instructor
Qualification	pilot : multi engine pilot : commercial pilot : instrument pilot : cfi
Experience	controller radar : 5.5 flight time last 90 days : 400 flight time total : 800 flight time type : 95
ASRS Report	436658
Person 2
Affiliation	other
Function	instruction : trainee
Qualification	pilot : student
Events
Anomaly	altitude deviation : overshoot non adherence : clearance non adherence : published procedure non adherence : far other spatial deviation
Independent Detector	atc equipment other atc equipment : radar other controllera
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

My student and I were going to the south practice area to do ground reference maneuvers. I decided that this would be a good introduction to IMC. I asked for and received an IFR block altitude between 3000-5000 ft. We entered the clouds at approximately 3000 ft. We broke out on top approximately 3800-4000 ft. While I was explaining the importance of trusting your instruments and not trying to rely on visual references, I noticed my student seemed uneasy not being able to see the ground. I started down through the clouds. We broke out below the clouds, I glanced at the altimeter. I thought it read 3500 ft. As I continued to descend, I called moline departure to cancel IFR. The controller then advised me that I was at 2500 ft and descending. I immediately pitched to regain the altitude of 3000 ft. In the same transmission, the controller canceled my IFR and I was told to maintain VFR. How the problem arose: I misread the altimeter and inadvertently went below 3000 ft. Contributing factors: my student's uneasiness in IMC distraction my attention from the importance of my 3000 ft assigned altitude. How it was discovered: when I called to cancel IFR, ATC advised me that I was at 2500 ft.

Original NASA ASRS Text

Title: WHILE GIVING IMC ORIENTATION TO STUDENT, INSTRUCTOR PLT DSNDS THROUGH ASSIGNED ALT.

Narrative: MY STUDENT AND I WERE GOING TO THE S PRACTICE AREA TO DO GND REF MANEUVERS. I DECIDED THAT THIS WOULD BE A GOOD INTRODUCTION TO IMC. I ASKED FOR AND RECEIVED AN IFR BLOCK ALT BTWN 3000-5000 FT. WE ENTERED THE CLOUDS AT APPROX 3000 FT. WE BROKE OUT ON TOP APPROX 3800-4000 FT. WHILE I WAS EXPLAINING THE IMPORTANCE OF TRUSTING YOUR INSTS AND NOT TRYING TO RELY ON VISUAL REFS, I NOTICED MY STUDENT SEEMED UNEASY NOT BEING ABLE TO SEE THE GND. I STARTED DOWN THROUGH THE CLOUDS. WE BROKE OUT BELOW THE CLOUDS, I GLANCED AT THE ALTIMETER. I THOUGHT IT READ 3500 FT. AS I CONTINUED TO DSND, I CALLED MOLINE DEP TO CANCEL IFR. THE CTLR THEN ADVISED ME THAT I WAS AT 2500 FT AND DSNDING. I IMMEDIATELY PITCHED TO REGAIN THE ALT OF 3000 FT. IN THE SAME XMISSION, THE CTLR CANCELED MY IFR AND I WAS TOLD TO MAINTAIN VFR. HOW THE PROB AROSE: I MISREAD THE ALTIMETER AND INADVERTENTLY WENT BELOW 3000 FT. CONTRIBUTING FACTORS: MY STUDENT'S UNEASINESS IN IMC DISTR MY ATTN FROM THE IMPORTANCE OF MY 3000 FT ASSIGNED ALT. HOW IT WAS DISCOVERED: WHEN I CALLED TO CANCEL IFR, ATC ADVISED ME THAT I WAS AT 2500 FT.

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.