Flight crew of large transport had a TCAS ii alert but traffic was never pointed out by controller.

Attributes
ACN	173617
Time
Date	199103
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : pbi
State Reference	FL
Altitude	msl bound lower : 3600 msl bound upper : 4000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : pbi
Operator	general aviation : corporate
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	descent : approach descent other
Route In Use	arrival other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : commercial pilot : atp
Experience	flight time last 90 days : 80 flight time total : 7500 flight time type : 2500
ASRS Report	173617
Person 2
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : overshoot non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : regained aircraft control
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

On approach into west palm beach international airport, and while descending to 4000' MSL our TCAS ii showed an 'aircraft/target' about 10 O'clock and 3.5 mi at about our same altitude and descending at the same rate we were. We 'both captain and first officer' were looking to see this aircraft which we finally did spot however, during this time we went about 350-400' below our assigned altitude. We corrected this immediately and climbed back to 4000', a few seconds later we got a TA on this traffic. During this time approach control advised us about our altitude however, they never did advise us of that traffic. That aircraft appeared to be a glider doing acrobatics.

Original NASA ASRS Text

Title: FLT CREW OF LGT HAD A TCAS II ALERT BUT TRAFFIC WAS NEVER POINTED OUT BY CTLR.

Narrative: ON APCH INTO W PALM BEACH INTL ARPT, AND WHILE DSNDING TO 4000' MSL OUR TCAS II SHOWED AN 'ACFT/TARGET' ABOUT 10 O'CLOCK AND 3.5 MI AT ABOUT OUR SAME ALT AND DSNDING AT THE SAME RATE WE WERE. WE 'BOTH CAPT AND F/O' WERE LOOKING TO SEE THIS ACFT WHICH WE FINALLY DID SPOT HOWEVER, DURING THIS TIME WE WENT ABOUT 350-400' BELOW OUR ASSIGNED ALT. WE CORRECTED THIS IMMEDIATELY AND CLBED BACK TO 4000', A FEW SECS LATER WE GOT A TA ON THIS TFC. DURING THIS TIME APCH CTL ADVISED US ABOUT OUR ALT HOWEVER, THEY NEVER DID ADVISE US OF THAT TFC. THAT ACFT APPEARED TO BE A GLIDER DOING ACROBATICS.

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.