<< >> NASA ASRS Report 336757, May 1996

An air carrier aircraft with TCASII took evasive action climb and turn from an aircraft without TCASII in oceanic airspace.

Attributes
ACN	336757
Time
Date	199605
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : ozn
State Reference	FO
Altitude	msl bound lower : 33000 msl bound upper : 33000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : czqx
Operator	common carrier : air carrier
Make Model Name	B747-C/F
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	cruise other
Route In Use	enroute : atlantic
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	cruise other cruise other
Route In Use	enroute : atlantic
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : cfi pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 200 flight time total : 8200 flight time type : 2000
ASRS Report	336757
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : excursion from assigned altitude other anomaly other other spatial deviation
Independent Detector	other flight crewa other other : unspecified cockpit
Resolutory Action	flight crew : returned to intended course or assigned course flight crew : took evasive action other
Consequence	Other
Miss Distance	vertical : 2500
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

We were a B747 freighter flight cruising at 33000 ft on nat track B on may/sun/96. We were overtaking a flight that was at 3500 ft at N59000 W32000. As we passed under the B757, we noticed he started a turn and climb. We asked him on the common frequency why he took evasive action and he claimed his TCASII showed us as a conflict. He then said his TCASII showed us at the proper altitude. We had no TCASII on our aircraft due to the waiver for freighters. There was never any conflict that I could see. I feel the TCASII aircraft received a bad RA advisory. I think that if we had TCASII, that we would have had a better picture of what the B757 was doing.

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Original NASA ASRS Text

Title: AN ACR ACFT WITH TCASII TOOK EVASIVE ACTION CLB AND TURN FROM AN ACFT WITHOUT TCASII IN OCEANIC AIRSPACE.

Narrative: WE WERE A B747 FREIGHTER FLT CRUISING AT 33000 FT ON NAT TRACK B ON MAY/SUN/96. WE WERE OVERTAKING A FLT THAT WAS AT 3500 FT AT N59000 W32000. AS WE PASSED UNDER THE B757, WE NOTICED HE STARTED A TURN AND CLB. WE ASKED HIM ON THE COMMON FREQ WHY HE TOOK EVASIVE ACTION AND HE CLAIMED HIS TCASII SHOWED US AS A CONFLICT. HE THEN SAID HIS TCASII SHOWED US AT THE PROPER ALT. WE HAD NO TCASII ON OUR ACFT DUE TO THE WAIVER FOR FREIGHTERS. THERE WAS NEVER ANY CONFLICT THAT I COULD SEE. I FEEL THE TCASII ACFT RECEIVED A BAD RA ADVISORY. I THINK THAT IF WE HAD TCASII, THAT WE WOULD HAVE HAD A BETTER PICTURE OF WHAT THE B757 WAS DOING.

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.