TCASII RA descend.

Attributes
ACN	256325
Time
Date	199311
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : cdw
State Reference	NJ
Altitude	msl bound lower : 3700 msl bound upper : 4000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : n90
Operator	general aviation : corporate
Make Model Name	Medium Transport
Navigation In Use	Other
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : atp pilot : cfi pilot : commercial pilot : instrument
Experience	flight time last 90 days : 60 flight time total : 11000 flight time type : 3000
ASRS Report	256325
Person 2
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

While flying directly over caldwell airport at 4000 ft, TCASII commanded the aircraft to descend at a rate of 1500 FPM. At 3700 ft the command to descend stopped, but did not say 'clear of conflict.' maintenance was advised but TCASII tested ok. New york approach did not have any traffic in our area and was very surprised by our 'TCASII descent.' I feel that someone was doing a transponder (mode C) check at caldwell. This would explain the quickness of the advisory and it suddenly disappearing.

Original NASA ASRS Text

Title: TCASII RA DSND.

Narrative: WHILE FLYING DIRECTLY OVER CALDWELL ARPT AT 4000 FT, TCASII COMMANDED THE ACFT TO DSND AT A RATE OF 1500 FPM. AT 3700 FT THE COMMAND TO DSND STOPPED, BUT DID NOT SAY 'CLR OF CONFLICT.' MAINT WAS ADVISED BUT TCASII TESTED OK. NEW YORK APCH DID NOT HAVE ANY TFC IN OUR AREA AND WAS VERY SURPRISED BY OUR 'TCASII DSCNT.' I FEEL THAT SOMEONE WAS DOING A XPONDER (MODE C) CHK AT CALDWELL. THIS WOULD EXPLAIN THE QUICKNESS OF THE ADVISORY AND IT SUDDENLY DISAPPEARING.

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.