C182 pilots have an altitude deviation during approach to pdk.

Attributes
ACN	718466
Time
Date	200611
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : a80.tracon
State Reference	GA
Altitude	msl single value : 3000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : a80.tracon
Operator	general aviation : personal
Make Model Name	Skylane 182/RG Turbo Skylane/RG
Operating Under FAR Part	Part 91
Flight Phase	descent : approach
Route In Use	arrival : on vectors
Flight Plan	IFR
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : commercial
Experience	flight time last 90 days : 4 flight time total : 530 flight time type : 150
ASRS Report	718466
Events
Anomaly	aircraft equipment problem : critical altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly
Independent Detector	other flight crewa
Resolutory Action	controller : issued new clearance none taken : anomaly accepted
Supplementary
Problem Areas	Weather Aircraft Flight Crew Human Performance
Primary Problem	Aircraft

Narrative:

We experienced a total directional gyro failure while in IMC on the missed approach procedure off winder airport (wdr) near athens; GA. We reported this to atl approach control. We were in IMC proceeding back to pdk airport; and were given vectors for the ILS runway 21 approach at pdk with an assigned altitude of 4000 ft. As we were turning to intercept the localizer; we noticed that we had descended to approximately 3200 ft. We do not know for sure how long we were below 4000 ft; but we would estimate that it was for 1 min or so. As soon as we noticed the deviation; we began a climb back to 4000 ft. We contacted the controller to confirm that we had been assigned 4000 ft and not 3000 ft. The controller said we were assigned 4000 ft; but that 3400 ft was our new assigned altitude. The rest of the flight was normal. A contributing factor to the altitude loss was that we were looking at the wet compass and the CDI during the turn to intercept the ILS. Since the wet compass takes time to settle; we were focusing on this to assure ourselves that we had turned to the proper heading for the approach. Another contributing factor is that we were in IMC at the time without reference to any external references which would have let us know that we had lost altitude. Another contributing factor is that the PF had only approximately 4 hours of flying in the past 90 days.

Original NASA ASRS Text

Title: C182 PLTS HAVE AN ALTDEV DURING APCH TO PDK.

Narrative: WE EXPERIENCED A TOTAL DIRECTIONAL GYRO FAILURE WHILE IN IMC ON THE MISSED APCH PROC OFF WINDER ARPT (WDR) NEAR ATHENS; GA. WE RPTED THIS TO ATL APCH CTL. WE WERE IN IMC PROCEEDING BACK TO PDK ARPT; AND WERE GIVEN VECTORS FOR THE ILS RWY 21 APCH AT PDK WITH AN ASSIGNED ALT OF 4000 FT. AS WE WERE TURNING TO INTERCEPT THE LOC; WE NOTICED THAT WE HAD DSNDED TO APPROX 3200 FT. WE DO NOT KNOW FOR SURE HOW LONG WE WERE BELOW 4000 FT; BUT WE WOULD ESTIMATE THAT IT WAS FOR 1 MIN OR SO. AS SOON AS WE NOTICED THE DEV; WE BEGAN A CLB BACK TO 4000 FT. WE CONTACTED THE CTLR TO CONFIRM THAT WE HAD BEEN ASSIGNED 4000 FT AND NOT 3000 FT. THE CTLR SAID WE WERE ASSIGNED 4000 FT; BUT THAT 3400 FT WAS OUR NEW ASSIGNED ALT. THE REST OF THE FLT WAS NORMAL. A CONTRIBUTING FACTOR TO THE ALT LOSS WAS THAT WE WERE LOOKING AT THE WET COMPASS AND THE CDI DURING THE TURN TO INTERCEPT THE ILS. SINCE THE WET COMPASS TAKES TIME TO SETTLE; WE WERE FOCUSING ON THIS TO ASSURE OURSELVES THAT WE HAD TURNED TO THE PROPER HDG FOR THE APCH. ANOTHER CONTRIBUTING FACTOR IS THAT WE WERE IN IMC AT THE TIME WITHOUT REF TO ANY EXTERNAL REFS WHICH WOULD HAVE LET US KNOW THAT WE HAD LOST ALT. ANOTHER CONTRIBUTING FACTOR IS THAT THE PF HAD ONLY APPROX 4 HRS OF FLYING IN THE PAST 90 DAYS.

Data retrieved from NASA's ASRS site as of January 2009 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.