Air carrier taxis into critical area of ILS antenna, forces a go around.

Attributes
ACN	157674
Time
Date	199009
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : ord
State Reference	IL
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : mlb
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 4 Turbojet Eng
Navigation In Use	Other
Flight Phase	ground : holding ground other : taxi
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	descent : approach landing : go around
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 225 flight time total : 19000 flight time type : 2200
ASRS Report	157674
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	other anomaly other
Independent Detector	other controllera
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

We were cleared to taxi from our gate to runway 27L via the outer, n-w lakeshore drive, 4R 22L parallel to 27L. We moved up in sequence following an air carrier-a medium large transport. There had been no landing that we had noticed on 27L during our taxi-out and I just assumed the runway 27L was for takeoffs only. When air carrier-a was cleared into position for takeoff, I taxied into his vacated space. This was in the ILS sensitive area. After the air carrier-a departure, tower was talking to air carrier-B aircraft advising him that he was below the glide path. Air carrier B complained of an erratic G/south. The tower said, 'I see why.' another aircraft went around. The taxiway on the north side of 27L was blocked by other aircraft also waiting for takeoff so tower cleared us for takeoff out of sequence to clear the ILS zone. We were not told to hold short of the ILS zone and unknowingly followed the preceding aircraft into the ILS sensitive zone being used by landing traffic.

Original NASA ASRS Text

Title: ACR TAXIS INTO CRITICAL AREA OF ILS ANTENNA, FORCES A GO AROUND.

Narrative: WE WERE CLRED TO TAXI FROM OUR GATE TO RWY 27L VIA THE OUTER, N-W LAKESHORE DRIVE, 4R 22L PARALLEL TO 27L. WE MOVED UP IN SEQUENCE FOLLOWING AN ACR-A MLG. THERE HAD BEEN NO LNDG THAT WE HAD NOTICED ON 27L DURING OUR TAXI-OUT AND I JUST ASSUMED THE RWY 27L WAS FOR TKOFS ONLY. WHEN ACR-A WAS CLRED INTO POS FOR TKOF, I TAXIED INTO HIS VACATED SPACE. THIS WAS IN THE ILS SENSITIVE AREA. AFTER THE ACR-A DEP, TWR WAS TALKING TO ACR-B ACFT ADVISING HIM THAT HE WAS BELOW THE GLIDE PATH. ACR B COMPLAINED OF AN ERRATIC G/S. THE TWR SAID, 'I SEE WHY.' ANOTHER ACFT WENT AROUND. THE TXWY ON THE N SIDE OF 27L WAS BLOCKED BY OTHER ACFT ALSO WAITING FOR TKOF SO TWR CLRED US FOR TKOF OUT OF SEQUENCE TO CLR THE ILS ZONE. WE WERE NOT TOLD TO HOLD SHORT OF THE ILS ZONE AND UNKNOWINGLY FOLLOWED THE PRECEDING ACFT INTO THE ILS SENSITIVE ZONE BEING USED BY LNDG 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.