Confusion in ord tower when air carrier medium large transport reports flap warning horn at takeoff, then has transmission advising continuation of takeoff by flight crew blocked by frequency congestion.

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Attributes
ACN	136505
Time
Date	199002
Day	Mon
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	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	climbout : takeoff
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 20000 flight time type : 400
ASRS Report	136505
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 3000 flight time type : 250
ASRS Report	136504
Events
Anomaly	aircraft equipment problem : less severe other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : overcame equipment problem
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Aircraft was cleared for takeoff by ord on runway 27L. Engines were brought up to 1.4 EPR and an aural flap warning sounded. At my direction copilot informed tower of our flap warning. An immediate check found that the flap setting indicator at the left side of pedestal was positioned at 9.5 degrees. The indicator in no way controls actual position of flaps/slats. They were properly set at 11 degrees and takeoff. Indicator was reset to 11 degrees and warning ceased. Copilot told tower we were continuing takeoff roll. This second transmission was apparently blocked by other aircraft xmissions because tower asked if we were aborting. He again informed them we were continuing takeoff. I elected to continue because source of warning was immediately found, aircraft gross weight was low (108.0) and sufficient runway remained for safe takeoff or abort if any further problem occurred prior to or at V1. At no time did tower cancel our takeoff clearance. Although situation was under control in cockpit and posed no safety problems, a moment of confusion existed in tower because our second transmission was blocked by other aircraft.

Original NASA ASRS Text

Title: CONFUSION IN ORD TWR WHEN ACR MLG REPORTS FLAP WARNING HORN AT TKOF, THEN HAS TRANSMISSION ADVISING CONTINUATION OF TKOF BY FLT CREW BLOCKED BY FREQ CONGESTION.

Narrative: ACFT WAS CLRED FOR TKOF BY ORD ON RWY 27L. ENGS WERE BROUGHT UP TO 1.4 EPR AND AN AURAL FLAP WARNING SOUNDED. AT MY DIRECTION COPLT INFORMED TWR OF OUR FLAP WARNING. AN IMMEDIATE CHK FOUND THAT THE FLAP SETTING INDICATOR AT THE LEFT SIDE OF PEDESTAL WAS POSITIONED AT 9.5 DEGS. THE INDICATOR IN NO WAY CONTROLS ACTUAL POS OF FLAPS/SLATS. THEY WERE PROPERLY SET AT 11 DEGS AND TKOF. INDICATOR WAS RESET TO 11 DEGS AND WARNING CEASED. COPLT TOLD TWR WE WERE CONTINUING TKOF ROLL. THIS SECOND XMISSION WAS APPARENTLY BLOCKED BY OTHER ACFT XMISSIONS BECAUSE TWR ASKED IF WE WERE ABORTING. HE AGAIN INFORMED THEM WE WERE CONTINUING TKOF. I ELECTED TO CONTINUE BECAUSE SOURCE OF WARNING WAS IMMEDIATELY FOUND, ACFT GROSS WT WAS LOW (108.0) AND SUFFICIENT RWY REMAINED FOR SAFE TKOF OR ABORT IF ANY FURTHER PROB OCCURRED PRIOR TO OR AT V1. AT NO TIME DID TWR CANCEL OUR TKOF CLRNC. ALTHOUGH SITUATION WAS UNDER CONTROL IN COCKPIT AND POSED NO SAFETY PROBS, A MOMENT OF CONFUSION EXISTED IN TWR BECAUSE OUR SECOND XMISSION WAS BLOCKED BY OTHER ACFT.

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.