Widebody transport makes missed approach due to sighting aircraft on TCASII closing their separation...

Attributes
ACN	256213
Time
Date	199311
Day	Fri
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : dtw
State Reference	MI
Altitude	msl bound lower : 3000 msl bound upper : 4000
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : dtw
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 3 Turbojet Eng
Navigation In Use	Other
Flight Phase	descent : approach
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : second officer
Qualification	pilot : instrument pilot : commercial pilot : cfi pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 100 flight time total : 10500 flight time type : 4200
ASRS Report	256213
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 98 flight time total : 12200 flight time type : 1400
ASRS Report	256046
Events
Anomaly	other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action other
Consequence	faa : reviewed incident with flight crew
Miss Distance	vertical : 0
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation other

Narrative:

On ILS approach to runway 21L at detroit, mi. We were on the localizer level at 3000 ft in WX with a strong right crosswind, ice, and turbulence, waiting for GS intercept. Approach control was conducting simultaneous approachs to runway 21R. The captain noticed another aircraft to our right on the TCASII initially 300 ft higher. In a short time the aircraft appeared to be getting closer horizontally and 100 ft vertically. The captain felt very uncomfortable and elected to make a go around and added power and climbed to approximately 4000 ft. We informed approach and they said to maintain 3000 ft which was the published go around altitude. It took several radio calls to explain we left 3000 ft to avoid the other aircraft on TCASII and they finally cleared us to 4000 ft and sequenced us for another approach. In retrospect approach had not informed us of the other aircraft so close on simultaneous approach (even though we assumed he was, we didn't know he was on his localizer). For our part we could have taken slight evasive action while asking approach about the traffic.

Original NASA ASRS Text

Title: WDB MAKES MISSED APCH DUE TO SIGHTING ACFT ON TCASII CLOSING THEIR SEPARATION.

Narrative: ON ILS APCH TO RWY 21L AT DETROIT, MI. WE WERE ON THE LOC LEVEL AT 3000 FT IN WX WITH A STRONG R XWIND, ICE, AND TURB, WAITING FOR GS INTERCEPT. APCH CTL WAS CONDUCTING SIMULTANEOUS APCHS TO RWY 21R. THE CAPT NOTICED ANOTHER ACFT TO OUR R ON THE TCASII INITIALLY 300 FT HIGHER. IN A SHORT TIME THE ACFT APPEARED TO BE GETTING CLOSER HORIZLY AND 100 FT VERTICALLY. THE CAPT FELT VERY UNCOMFORTABLE AND ELECTED TO MAKE A GAR AND ADDED PWR AND CLBED TO APPROX 4000 FT. WE INFORMED APCH AND THEY SAID TO MAINTAIN 3000 FT WHICH WAS THE PUBLISHED GAR ALT. IT TOOK SEVERAL RADIO CALLS TO EXPLAIN WE LEFT 3000 FT TO AVOID THE OTHER ACFT ON TCASII AND THEY FINALLY CLRED US TO 4000 FT AND SEQUENCED US FOR ANOTHER APCH. IN RETROSPECT APCH HAD NOT INFORMED US OF THE OTHER ACFT SO CLOSE ON SIMULTANEOUS APCH (EVEN THOUGH WE ASSUMED HE WAS, WE DIDN'T KNOW HE WAS ON HIS LOC). FOR OUR PART WE COULD HAVE TAKEN SLIGHT EVASIVE ACTION WHILE ASKING APCH ABOUT THE TFC.

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.