<< >> NASA ASRS Report 340700, July 1996

An air carrier B727 refused a descent clearance on the advice of TCASII. Descending would have caused an near midair collision with a VFR VMC bonanza.

Attributes
ACN	340700
Time
Date	199607
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : buj airport : dfw
State Reference	TX
Altitude	msl bound lower : 10000 msl bound upper : 10000
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zfw
Operator	common carrier : air carrier
Make Model Name	B727-200
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	cruise other
Route In Use	arrival other arrival star : star
Flight Plan	IFR
Aircraft 2
Make Model Name	Bonanza 35
Operating Under FAR Part	Part 91
Flight Phase	cruise other
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	340700
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	conflict : nmac non adherence : published procedure other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	vertical : 500
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	other

Narrative:

While flying the blue ridge 7 arrival to dfw, we were given a descent clearance from 10000 ft to 9000 ft. At the same time, TCASII was giving us a TA, for traffic at 12 O'clock, opposite direction at 9500 ft. We declined the clearance and the traffic, a beech bonanza, passed directly below us with 500 ft vertical clearance. At that time, TCASII was warning us to monitor vertical descent. At no time did ATC advice us of this traffic. When I asked them if they had the aircraft on radar, I was simply told that I was clear of traffic. I am convinced that following the initial clearance to 9000 ft would have resulted in a midair collision.

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Original NASA ASRS Text

Title: AN ACR B727 REFUSED A DSCNT CLRNC ON THE ADVICE OF TCASII. DSNDING WOULD HAVE CAUSED AN NMAC WITH A VFR VMC BONANZA.

Narrative: WHILE FLYING THE BLUE RIDGE 7 ARR TO DFW, WE WERE GIVEN A DSCNT CLRNC FROM 10000 FT TO 9000 FT. AT THE SAME TIME, TCASII WAS GIVING US A TA, FOR TFC AT 12 O'CLOCK, OPPOSITE DIRECTION AT 9500 FT. WE DECLINED THE CLRNC AND THE TFC, A BEECH BONANZA, PASSED DIRECTLY BELOW US WITH 500 FT VERT CLRNC. AT THAT TIME, TCASII WAS WARNING US TO MONITOR VERT DSCNT. AT NO TIME DID ATC ADVICE US OF THIS TFC. WHEN I ASKED THEM IF THEY HAD THE ACFT ON RADAR, I WAS SIMPLY TOLD THAT I WAS CLR OF TFC. I AM CONVINCED THAT FOLLOWING THE INITIAL CLRNC TO 9000 FT WOULD HAVE RESULTED IN A MIDAIR COLLISION.

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.