Instruction flight cleared for ILS approach descended from 2600 MSL to 2000 MSL to intercept the GS.

Attributes
ACN	187154
Time
Date	199108
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : roc
State Reference	NY
Altitude	msl bound lower : 2000 msl bound upper : 2600
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Controlling Facilities	tracon : roc
Operator	general aviation : instructional
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Retractable Gear
Flight Phase	descent : approach descent other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	instruction : instructor other personnel other
Qualification	pilot : commercial pilot : cfi pilot : instrument
Experience	flight time last 90 days : 130 flight time total : 1870 flight time type : 150
ASRS Report	187154
Person 2
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	other controllera
Resolutory Action	none taken : anomaly accepted
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Flight was local instrument instruction flight receiving radar vectors to ILS 4 roc from local approach controller. The approach is flown straight in from elroy at 2600 MSL to GS. If procedure turn is required descent to 2000 MSL is acceptable established inbound on localizer. When radar vectored 2000 MSL to GS is sometimes issued as final altitude. In this case controller instructions were maintain 2600 until established on localizer cleared ILS 4 approach. I continued to 2000 MSL once established on localizer inbound. The controller expected us to maintain 2600 to GS intercept. The controller questioned our altitude and alerted me to the misunderstanding. The approach was completed without incident. VFR conditions existed with airport in sight during entire procedure. I feel the use of both 2000 and 2600 MSL in past approachs led to my confusion in this case.

Original NASA ASRS Text

Title: INSTRUCTION FLT CLRED FOR ILS APCH DSNDED FROM 2600 MSL TO 2000 MSL TO INTERCEPT THE GS.

Narrative: FLT WAS LCL INST INSTRUCTION FLT RECEIVING RADAR VECTORS TO ILS 4 ROC FROM LCL APCH CTLR. THE APCH IS FLOWN STRAIGHT IN FROM ELROY AT 2600 MSL TO GS. IF PROC TURN IS REQUIRED DSCNT TO 2000 MSL IS ACCEPTABLE ESTABLISHED INBOUND ON LOC. WHEN RADAR VECTORED 2000 MSL TO GS IS SOMETIMES ISSUED AS FINAL ALT. IN THIS CASE CTLR INSTRUCTIONS WERE MAINTAIN 2600 UNTIL ESTABLISHED ON LOC CLRED ILS 4 APCH. I CONTINUED TO 2000 MSL ONCE ESTABLISHED ON LOC INBOUND. THE CTLR EXPECTED US TO MAINTAIN 2600 TO GS INTERCEPT. THE CTLR QUESTIONED OUR ALT AND ALERTED ME TO THE MISUNDERSTANDING. THE APCH WAS COMPLETED WITHOUT INCIDENT. VFR CONDITIONS EXISTED WITH ARPT IN SIGHT DURING ENTIRE PROC. I FEEL THE USE OF BOTH 2000 AND 2600 MSL IN PAST APCHS LED TO MY CONFUSION IN THIS CASE.

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.