Emj jet on approach to ord experienced ILS reception problem prompting go around.

Attributes
ACN	610307
Time
Date	200403
Day	Thu
Place
Locale Reference	airport : ord.airport
State Reference	IL
Altitude	agl single value : 1800
Aircraft 1
Controlling Facilities	tracon : c90.tracon
Operator	common carrier : air carrier
Make Model Name	Embraer Jet Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	ils localizer & glide slope : 9l
Flight Phase	descent : approach landing : missed approach
Route In Use	approach : instrument precision approach : traffic pattern
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	610307
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : multi engine pilot : commercial
ASRS Report	610310
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance flight crew : overrode automation flight crew : landed in emergency condition flight crew : declared emergency flight crew : executed go around
Consequence	faa : reviewed incident with flight crew other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

On the ILS to runway 9R, we got multiple erratic HSI deflections during the approach. As we approached ord at about 1800 ft AGL, we elected to abandon the approach. Decision was made to request a separate ILS frequency to try and solve the problem. Minimum fuel was declared. ATC started giving delay vectors for sequencing with traffic and they insisted that runway 9L was unavailable and it would have to be runway 9R. So we declared fuel critical and were given runway 9L and turned onto the ILS. On the ILS to runway 9L, both HSI's exhibited the same erratic behavior. We took the autoplt off and hand flew the approach electing to ignore the deflections that were out of the median/mean. Supplemental information from acn 610310: determined that it was not localizer signal, but our receivers. Chose to continue approach. CDI steadied just outside the marker.

Original NASA ASRS Text

Title: EMJ JET ON APCH TO ORD EXPERIENCED ILS RECEPTION PROB PROMPTING GAR.

Narrative: ON THE ILS TO RWY 9R, WE GOT MULTIPLE ERRATIC HSI DEFLECTIONS DURING THE APCH. AS WE APCHED ORD AT ABOUT 1800 FT AGL, WE ELECTED TO ABANDON THE APCH. DECISION WAS MADE TO REQUEST A SEPARATE ILS FREQ TO TRY AND SOLVE THE PROB. MINIMUM FUEL WAS DECLARED. ATC STARTED GIVING DELAY VECTORS FOR SEQUENCING WITH TFC AND THEY INSISTED THAT RWY 9L WAS UNAVAILABLE AND IT WOULD HAVE TO BE RWY 9R. SO WE DECLARED FUEL CRITICAL AND WERE GIVEN RWY 9L AND TURNED ONTO THE ILS. ON THE ILS TO RWY 9L, BOTH HSI'S EXHIBITED THE SAME ERRATIC BEHAVIOR. WE TOOK THE AUTOPLT OFF AND HAND FLEW THE APCH ELECTING TO IGNORE THE DEFLECTIONS THAT WERE OUT OF THE MEDIAN/MEAN. SUPPLEMENTAL INFO FROM ACN 610310: DETERMINED THAT IT WAS NOT LOC SIGNAL, BUT OUR RECEIVERS. CHOSE TO CONTINUE APCH. CDI STEADIED JUST OUTSIDE THE MARKER.

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.