Light transport on IFR flight plan has near midair collision with small transport during descent.

Attributes
ACN	241068
Time
Date	199305
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : hou
State Reference	NY
Altitude	msl bound lower : 7000 msl bound upper : 7800
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Operator	other
Make Model Name	Light Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Route In Use	enroute : on vectors enroute airway : n90
Flight Plan	IFR
Aircraft 2
Make Model Name	Small Transport, Low Wing, 2 Turboprop Eng
Flight Phase	climbout : intermediate altitude
Person 1
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial pilot : cfi
Experience	flight time last 90 days : 100 flight time total : 2300 flight time type : 200
ASRS Report	241068
Person 2
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : nmac inflight encounter : vfr in imc non adherence : far
Independent Detector	other flight crewa
Resolutory Action	none taken : insufficient time
Consequence	Other
Miss Distance	horizontal : 0 vertical : 300
Supplementary
Primary Problem	Flight Crew Human Performance

Narrative:

While descending between hugunot and coate on the northern arrival into teterboro, controller alerted us to traffic '12 O'clock and 8 mi, opposite direction, 6000 ft appears to be climbing, type unknown.' we were in a descent to 7000 ft and were in and out of cumulus clouds. I reported the traffic not in sight and the controller issued a left turn to 120 degrees and reported the traffic 12 - 1 O'clock, 6600 ft in a 'slow climb.' this position and altitude put the traffic in cumulus and it was not in sight. I reported the aircraft not in sight. Controller issued an immediate left turn to 090 degrees and a climb to 7500 ft. The captain reacted rather slowly to this call for immediate turn and climb and as it turned out the aircraft (an small transport) popped out of a cumulus cloud about 300 ft above us and just left of the nose of our aircraft (light transport). Had he followed the controller's commands exactly, there is no doubt in my mind we could have hit the other aircraft. I used to criticize TCASII as an overly expensive over-reaction. I am now convinced of its validity.

Original NASA ASRS Text

Title: LTT ON IFR FLT PLAN HAS NMAC WITH SMT DURING DSCNT.

Narrative: WHILE DSNDING BTWN HUGUNOT AND COATE ON THE NORTHERN ARR INTO TETERBORO, CTLR ALERTED US TO TFC '12 O'CLOCK AND 8 MI, OPPOSITE DIRECTION, 6000 FT APPEARS TO BE CLBING, TYPE UNKNOWN.' WE WERE IN A DSCNT TO 7000 FT AND WERE IN AND OUT OF CUMULUS CLOUDS. I RPTED THE TFC NOT IN SIGHT AND THE CTLR ISSUED A L TURN TO 120 DEGS AND RPTED THE TFC 12 - 1 O'CLOCK, 6600 FT IN A 'SLOW CLB.' THIS POS AND ALT PUT THE TFC IN CUMULUS AND IT WAS NOT IN SIGHT. I RPTED THE ACFT NOT IN SIGHT. CTLR ISSUED AN IMMEDIATE L TURN TO 090 DEGS AND A CLB TO 7500 FT. THE CAPT REACTED RATHER SLOWLY TO THIS CALL FOR IMMEDIATE TURN AND CLB AND AS IT TURNED OUT THE ACFT (AN SMT) POPPED OUT OF A CUMULUS CLOUD ABOUT 300 FT ABOVE US AND JUST L OF THE NOSE OF OUR ACFT (LTT). HAD HE FOLLOWED THE CTLR'S COMMANDS EXACTLY, THERE IS NO DOUBT IN MY MIND WE COULD HAVE HIT THE OTHER ACFT. I USED TO CRITICIZE TCASII AS AN OVERLY EXPENSIVE OVER-REACTION. I AM NOW CONVINCED OF ITS VALIDITY.

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.