Narrative:

While taxing out of an FBO at chicago O'hare airport heading toward the active runway in use the crew began performing the taxi checklist. When the crew was checking the speed brake warning as per aircraft owners manual, the crew found that the warning horn was not activating properly. At the time of this discovery our aircraft was approaching the hold short line of the active runway in use. We were holding short of the active runway trying to activate the warning horn by performing several tests when the tower cleared us for takeoff. Before answering the tower I (first officer/PNF) asked the captain if he would like more time to assess the problem! This was my way of saying we need to address the problem and pull into the block area. The captain's response was, 'no, let's go.' at this time I acknowledged the tower and at the same time performed a silent self-check of all items affiliated with the takeoff warning horn. With all items checked we started our takeoff roll and continued our flight to destination without incident. Some of the factors leading up to this event: trying to get back on schedule which led to a feeling of being rushed, low time/inexperienced captain, captain's disregard of crew input in dealing with situation. The most important corrective action items in this scenario are to never lose sight of items concerning 'safety of flight,' and never rush in any situation. No matter how long it takes or whatever level of experience an individual possesses, always include in your decision making process your crew inputs and utilize your basic cockpit resource management procedures! Callback conversation with reporter revealed the following information: received callbacks from both the first officer and the so of the flight. When accomplishing the before takeoff checklist, the speed brake warning check was not satisfactory. Normally, when all takeoff parameters are met, flaps, speed brake and trim, and the speed brake warning horn is checked, it would not sound if all were set properly. Then, if the speed brake was brought out, with a throttle advanced, the warning would sound. Both flight crew rptrs were concerned about their captain's lack of heeding their input to take more time to assess the problem. They had already been delayed, they were #1 for takeoff and the captain considered it safe to takeoff, in spite of the fact that an important warning system was apparently not working properly.

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Original NASA ASRS Text

Title: WHILE PERFORMING THE TKOF CHKLIST, THE SPD BRAKE WARNING CHK WAS NOT SATISFACTORY. BEING #1 FOR TKOF AND ALREADY DELAYED FLT, CAPT DECIDED TO TKOF ANYWAY.

Narrative: WHILE TAXING OUT OF AN FBO AT CHICAGO O'HARE ARPT HEADING TOWARD THE ACTIVE RWY IN USE THE CREW BEGAN PERFORMING THE TAXI CHKLIST. WHEN THE CREW WAS CHKING THE SPD BRAKE WARNING AS PER ACFT OWNERS MANUAL, THE CREW FOUND THAT THE WARNING HORN WAS NOT ACTIVATING PROPERLY. AT THE TIME OF THIS DISCOVERY OUR ACFT WAS APCHING THE HOLD SHORT LINE OF THE ACTIVE RWY IN USE. WE WERE HOLDING SHORT OF THE ACTIVE RWY TRYING TO ACTIVATE THE WARNING HORN BY PERFORMING SEVERAL TESTS WHEN THE TWR CLRED US FOR TKOF. BEFORE ANSWERING THE TWR I (FO/PNF) ASKED THE CAPT IF HE WOULD LIKE MORE TIME TO ASSESS THE PROB! THIS WAS MY WAY OF SAYING WE NEED TO ADDRESS THE PROB AND PULL INTO THE BLOCK AREA. THE CAPT'S RESPONSE WAS, 'NO, LET'S GO.' AT THIS TIME I ACKNOWLEDGED THE TWR AND AT THE SAME TIME PERFORMED A SILENT SELF-CHK OF ALL ITEMS AFFILIATED WITH THE TKOF WARNING HORN. WITH ALL ITEMS CHKED WE STARTED OUR TKOF ROLL AND CONTINUED OUR FLT TO DEST WITHOUT INCIDENT. SOME OF THE FACTORS LEADING UP TO THIS EVENT: TRYING TO GET BACK ON SCHEDULE WHICH LED TO A FEELING OF BEING RUSHED, LOW TIME/INEXPERIENCED CAPT, CAPT'S DISREGARD OF CREW INPUT IN DEALING WITH SIT. THE MOST IMPORTANT CORRECTIVE ACTION ITEMS IN THIS SCENARIO ARE TO NEVER LOSE SIGHT OF ITEMS CONCERNING 'SAFETY OF FLT,' AND NEVER RUSH IN ANY SIT. NO MATTER HOW LONG IT TAKES OR WHATEVER LEVEL OF EXPERIENCE AN INDIVIDUAL POSSESSES, ALWAYS INCLUDE IN YOUR DECISION MAKING PROCESS YOUR CREW INPUTS AND UTILIZE YOUR BASIC COCKPIT RESOURCE MGMNT PROCS! CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RECEIVED CALLBACKS FROM BOTH THE FO AND THE SO OF THE FLT. WHEN ACCOMPLISHING THE BEFORE TKOF CHKLIST, THE SPD BRAKE WARNING CHK WAS NOT SATISFACTORY. NORMALLY, WHEN ALL TKOF PARAMETERS ARE MET, FLAPS, SPD BRAKE AND TRIM, AND THE SPD BRAKE WARNING HORN IS CHKED, IT WOULD NOT SOUND IF ALL WERE SET PROPERLY. THEN, IF THE SPD BRAKE WAS BROUGHT OUT, WITH A THROTTLE ADVANCED, THE WARNING WOULD SOUND. BOTH FLC RPTRS WERE CONCERNED ABOUT THEIR CAPT'S LACK OF HEEDING THEIR INPUT TO TAKE MORE TIME TO ASSESS THE PROB. THEY HAD ALREADY BEEN DELAYED, THEY WERE #1 FOR TKOF AND THE CAPT CONSIDERED IT SAFE TO TKOF, IN SPITE OF THE FACT THAT AN IMPORTANT WARNING SYS WAS APPARENTLY NOT WORKING PROPERLY.

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.