Close proximity air carrier-large transport air carrier-unk on parallel approachs to dtw.

Attributes
ACN	98689
Time
Date	198811
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : dtw
State Reference	MI
Altitude	msl bound lower : 2300 msl bound upper : 2300
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : dtw tower : phl
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	descent : approach
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : flight engineer pilot : commercial pilot : cfi pilot : atp
Experience	flight time last 90 days : 150 flight time total : 14000
ASRS Report	98689
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	conflict : airborne less severe non adherence : clearance other spatial deviation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Miss Distance	horizontal : 6000 vertical : 0
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Cleared approach to runway 21L. Approach gave vector heading 240 degree to intercept. One minute later approach controller said turn left to avoid traffic on right runway 21R. Approach map shift on HSI causing an approach to 21C or 21R. No missed approach was taken. Successful alignment with 21L was accomplished with raw data. I believe parallel approachs in marginal VFR conditions are an accident waiting to happen.

Original NASA ASRS Text

Title: CLOSE PROX ACR-LGT ACR-UNK ON PARALLEL APCHS TO DTW.

Narrative: CLRED APCH TO RWY 21L. APCH GAVE VECTOR HDG 240 DEG TO INTERCEPT. ONE MINUTE LATER APCH CTLR SAID TURN LEFT TO AVOID TFC ON RIGHT RWY 21R. APCH MAP SHIFT ON HSI CAUSING AN APCH TO 21C OR 21R. NO MISSED APCH WAS TAKEN. SUCCESSFUL ALIGNMENT WITH 21L WAS ACCOMPLISHED WITH RAW DATA. I BELIEVE PARALLEL APCHS IN MARGINAL VFR CONDITIONS ARE AN ACCIDENT WAITING TO HAPPEN.

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.