Medium large transport in positive control area has TCASII RA, responds.

Attributes
ACN	236735
Time
Date	199303
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : uin
State Reference	IL
Altitude	msl bound lower : 23500 msl bound upper : 24000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zkc
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Route In Use	arrival other
Flight Plan	IFR
Aircraft 2
Operator	other
Make Model Name	Fighter
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 130 flight time total : 11000 flight time type : 900
ASRS Report	236735
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : nmac non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 700 vertical : 500
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Flight operating oma-stl. While inbound on the rivers 1 arrival between irk and uin and at assigned altitude FL240, the following event transpired. TCASII showed a red TA at approximately 11-12 O'clock, 1600 ft above, but descending. Sighting visually, I observed 2 military fgt types, in loose formation, crossing the flight path from left to right at approximately 90 degree angle and higher. Immediately thereafter the TCASII aural alert sounded 'descend, descend.' the captain commanded descend, I disengaged the autoplt and pushed the aircraft over to descend. I looked up and saw a third military aircraft at 11:30 position, in a hard left bank and climb. This aircraft was slightly above and in front, passing left to right. After this aircraft cleared and with no further TCASII alerts I pulled back up to altitude. An inquiry was made of ZKC about the flight and the controller advised of a military flight at FL250. I believe without the TCASII a midair might have occurred. It appeared that at least one of the military aircraft in the flight was not at his assigned altitude.

Original NASA ASRS Text

Title: MLG IN PCA HAS TCASII RA, RESPONDS.

Narrative: FLT OPERATING OMA-STL. WHILE INBOUND ON THE RIVERS 1 ARR BTWN IRK AND UIN AND AT ASSIGNED ALT FL240, THE FOLLOWING EVENT TRANSPIRED. TCASII SHOWED A RED TA AT APPROX 11-12 O'CLOCK, 1600 FT ABOVE, BUT DSNDING. SIGHTING VISUALLY, I OBSERVED 2 MIL FGT TYPES, IN LOOSE FORMATION, XING THE FLT PATH FROM L TO R AT APPROX 90 DEG ANGLE AND HIGHER. IMMEDIATELY THEREAFTER THE TCASII AURAL ALERT SOUNDED 'DSND, DSND.' THE CAPT COMMANDED DSND, I DISENGAGED THE AUTOPLT AND PUSHED THE ACFT OVER TO DSND. I LOOKED UP AND SAW A THIRD MIL ACFT AT 11:30 POS, IN A HARD L BANK AND CLB. THIS ACFT WAS SLIGHTLY ABOVE AND IN FRONT, PASSING L TO R. AFTER THIS ACFT CLRED AND WITH NO FURTHER TCASII ALERTS I PULLED BACK UP TO ALT. AN INQUIRY WAS MADE OF ZKC ABOUT THE FLT AND THE CTLR ADVISED OF A MIL FLT AT FL250. I BELIEVE WITHOUT THE TCASII A MIDAIR MIGHT HAVE OCCURRED. IT APPEARED THAT AT LEAST ONE OF THE MIL ACFT IN THE FLT WAS NOT AT HIS ASSIGNED ALT.

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.