Small aircraft has near midair collision with commuter aircraft on IMC approach.

Attributes
ACN	275221
Time
Date	199406
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : cwa
State Reference	WI
Altitude	msl bound lower : 3000 msl bound upper : 4000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zmp
Operator	general aviation : personal
Make Model Name	M-20 J (201)
Operating Under FAR Part	Part 91
Flight Phase	descent : approach
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 135
Flight Phase	descent : approach
Route In Use	approach : straight in
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private pilot : instrument
Experience	flight time last 90 days : 30 flight time total : 400 flight time type : 100
ASRS Report	275221
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : nmac non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	none taken : insufficient time
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 300 vertical : 0
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Problem situation: 2 aircraft converging on ILS runway 8 approach at cwa (non radar controled). 1 aircraft was (on final) inbound at 3000 ft and 1 was outbound on initial procedure turn (same radial/bearing). According to center controller, outbound aircraft was to have maintained 4000 ft. Outbound pilot understood instructions to be maintain 4000 ft until or to danci (initial approach fix), report danci outbound. Upon reporting danci outbound, outbound pilot descended from 4000 ft to the published approach mins of 3000 ft. Discovery: outbound pilot reported altitude of 3000 ft. Inbound commuter pilot reported passing outbound plane within 300 ft at the same altitude. Contributing factors center controllers intent was to avoid a normal hold for the outbound aircraft by an extended outbound procedure turn at an altitude 1000 ft higher than the published minimums for the approach. Contributing factors: the situation and intent of the center controller was not communicated to the outbound pilot. Upon reporting 'danci outbound' (initial approach fix). No mention of altitude, i.e., 'maintain 4000 ft' was communicated by center to the outbound pilot. Corrective action: at non radar IFR approach environments, if non published or standard approach procedures and/or altitudes are given, the center controllers should: 1) outline the situation and the changes (this would increase understanding and communication) to the pilots. 2) reinforce the instructions at different reporting points and/or fixes to the pilot.

Original NASA ASRS Text

Title: SMA HAS NMAC WITH COMMUTER ACFT ON IMC APCH.

Narrative: PROB SIT: 2 ACFT CONVERGING ON ILS RWY 8 APCH AT CWA (NON RADAR CTLED). 1 ACFT WAS (ON FINAL) INBOUND AT 3000 FT AND 1 WAS OUTBOUND ON INITIAL PROC TURN (SAME RADIAL/BEARING). ACCORDING TO CTR CTLR, OUTBOUND ACFT WAS TO HAVE MAINTAINED 4000 FT. OUTBOUND PLT UNDERSTOOD INSTRUCTIONS TO BE MAINTAIN 4000 FT UNTIL OR TO DANCI (INITIAL APCH FIX), RPT DANCI OUTBOUND. UPON RPTING DANCI OUTBOUND, OUTBOUND PLT DSNDED FROM 4000 FT TO THE PUBLISHED APCH MINS OF 3000 FT. DISCOVERY: OUTBOUND PLT RPTED ALT OF 3000 FT. INBOUND COMMUTER PLT RPTED PASSING OUTBOUND PLANE WITHIN 300 FT AT THE SAME ALT. CONTRIBUTING FACTORS CTR CTLRS INTENT WAS TO AVOID A NORMAL HOLD FOR THE OUTBOUND ACFT BY AN EXTENDED OUTBOUND PROC TURN AT AN ALT 1000 FT HIGHER THAN THE PUBLISHED MINIMUMS FOR THE APCH. CONTRIBUTING FACTORS: THE SIT AND INTENT OF THE CTR CTLR WAS NOT COMMUNICATED TO THE OUTBOUND PLT. UPON RPTING 'DANCI OUTBOUND' (INITIAL APCH FIX). NO MENTION OF ALT, I.E., 'MAINTAIN 4000 FT' WAS COMMUNICATED BY CTR TO THE OUTBOUND PLT. CORRECTIVE ACTION: AT NON RADAR IFR APCH ENVIRONMENTS, IF NON PUBLISHED OR STANDARD APCH PROCS AND/OR ALTS ARE GIVEN, THE CTR CTLRS SHOULD: 1) OUTLINE THE SIT AND THE CHANGES (THIS WOULD INCREASE UNDERSTANDING AND COM) TO THE PLTS. 2) REINFORCE THE INSTRUCTIONS AT DIFFERENT RPTING POINTS AND/OR FIXES TO THE PLT.

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.