Reporter aircraft descended below minimum altitude inbound to the final approach fix.

Attributes
ACN	119819
Time
Date	198908
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : jot
State Reference	IL
Altitude	msl bound lower : 1500 msl bound upper : 2500
Environment
Flight Conditions	Marginal
Light	Night
Aircraft 1
Controlling Facilities	artcc : zau
Operator	common carrier : air taxi
Make Model Name	Small Aircraft, Low Wing, 2 Eng, Retractable Gear
Flight Phase	descent : approach descent other
Flight Plan	IFR
Person 1
Affiliation	company : air taxi
Function	flight crew : single pilot
Qualification	other other : other pilot : commercial pilot : cfi pilot : atp pilot : instrument
Experience	flight time last 90 days : 300 flight time total : 2000 flight time type : 400
ASRS Report	119819
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance non adherence : published procedure other spatial deviation
Independent Detector	other flight crewa
Resolutory Action	flight crew : exited adverse environment none taken : detected after the fact other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

On vectors for the approach. Was cleared for approach and told to maintain 2500 MSL until established. Had studies approach plate twice while en route and had the numbers memorized. Once inbound, I began a slow descent towards the MDA and consequently arrived over the FAF below minimum altitude. I immediately executed missed approach and requested the approach again. Approach cleared me for a second approach and I did the approach as published, making a normal landing. Callback conversation with reporter revealed the following: reporter states that the only cause of this incident was his misreading and misinterpreting the approach plate. He states that he has made similar apches many times and is at a loss to explain this incident.

Original NASA ASRS Text

Title: REPORTER ACFT DESCENDED BELOW MINIMUM ALT INBOUND TO THE FINAL APCH FIX.

Narrative: ON VECTORS FOR THE APCH. WAS CLRED FOR APCH AND TOLD TO MAINTAIN 2500 MSL UNTIL ESTABLISHED. HAD STUDIES APCH PLATE TWICE WHILE ENRTE AND HAD THE NUMBERS MEMORIZED. ONCE INBND, I BEGAN A SLOW DSCNT TOWARDS THE MDA AND CONSEQUENTLY ARRIVED OVER THE FAF BELOW MINIMUM ALT. I IMMEDIATELY EXECUTED MISSED APCH AND REQUESTED THE APCH AGAIN. APCH CLRED ME FOR A SECOND APCH AND I DID THE APCH AS PUBLISHED, MAKING A NORMAL LNDG. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING: REPORTER STATES THAT THE ONLY CAUSE OF THIS INCIDENT WAS HIS MISREADING AND MISINTERPRETING THE APCH PLATE. HE STATES THAT HE HAS MADE SIMILAR APCHES MANY TIMES AND IS AT A LOSS TO EXPLAIN THIS INCIDENT.

Data retrieved from NASA's ASRS site as of August 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.