TCASII. Intruder traffic reported by ATC and flight crew had it visually, but the traffic was descen...

Attributes
ACN	340773
Time
Date	199607
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : dlg
State Reference	AK
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zan
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 135
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Aircraft 2
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	other : unknown
Flight Phase	cruise other descent other
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 300 flight time total : 17000 flight time type : 6000
ASRS Report	340773
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	conflict : airborne less severe
Independent Detector	other controllera other flight crewa
Resolutory Action	none taken : anomaly accepted
Consequence	Other
Supplementary
Air Traffic Incident	other

Narrative:

ATC advised us of jet traffic on a descent to dlg. I replied and told them to keep us advised of their position. ATC advised us again of the jet's position at the same time the traffic showed up on our TCASII (15 mi). At that time I turned on the landing lights and advised my first officer to look for the traffic. At 6 mi on the TCASII, my first officer spotted traffic at 11:30 O'clock and slightly higher. At that time I saw the traffic also and advised ATC that we had traffic in sight. I kept traffic in sight and at approximately 2 mi the jet was descending below our altitude and I told my first officer traffic would be no factor. Then to my first officer's and my surprise, the jet stopped its descent and started to climb. Even though I could tell the jet would pass well off our left side, I told my first officer to turn 20 degrees right just to make sure. I never lost sight of the jet, however, I was confused at why it was climbing since we were above its position. Just prior to the jet becoming abeam our position and now at our altitude, the crew must have seen us because they made a very sharp right turn. At no time did I or my first officer feel we were in danger of a midair and were a little confused at all the maneuvering the jet was making. After the jet passed off our left side at window level I did not feel it was close enough to warrant even an explanation to the passenger. I also do not think ATC did anything unsafe or inappropriate.

Original NASA ASRS Text

Title: TCASII. INTRUDER TFC RPTED BY ATC AND FLC HAD IT VISUALLY, BUT THE TFC WAS DSNDING AND RPTR SAID IT DSNDED BELOW THEIR ALT WHEN SUDDENLY IT STARTED A CLB. RPTR WAS CONFUSED WHY THE TFC STARTED A CLB OUT OF A DSCNT. TFC WAS NEVER CLOSER THAN 2 MI.

Narrative: ATC ADVISED US OF JET TFC ON A DSCNT TO DLG. I REPLIED AND TOLD THEM TO KEEP US ADVISED OF THEIR POS. ATC ADVISED US AGAIN OF THE JET'S POS AT THE SAME TIME THE TFC SHOWED UP ON OUR TCASII (15 MI). AT THAT TIME I TURNED ON THE LNDG LIGHTS AND ADVISED MY FO TO LOOK FOR THE TFC. AT 6 MI ON THE TCASII, MY FO SPOTTED TFC AT 11:30 O'CLOCK AND SLIGHTLY HIGHER. AT THAT TIME I SAW THE TFC ALSO AND ADVISED ATC THAT WE HAD TFC IN SIGHT. I KEPT TFC IN SIGHT AND AT APPROX 2 MI THE JET WAS DSNDING BELOW OUR ALT AND I TOLD MY FO TFC WOULD BE NO FACTOR. THEN TO MY FO'S AND MY SURPRISE, THE JET STOPPED ITS DSCNT AND STARTED TO CLB. EVEN THOUGH I COULD TELL THE JET WOULD PASS WELL OFF OUR L SIDE, I TOLD MY FO TO TURN 20 DEGS R JUST TO MAKE SURE. I NEVER LOST SIGHT OF THE JET, HOWEVER, I WAS CONFUSED AT WHY IT WAS CLBING SINCE WE WERE ABOVE ITS POS. JUST PRIOR TO THE JET BECOMING ABEAM OUR POS AND NOW AT OUR ALT, THE CREW MUST HAVE SEEN US BECAUSE THEY MADE A VERY SHARP R TURN. AT NO TIME DID I OR MY FO FEEL WE WERE IN DANGER OF A MIDAIR AND WERE A LITTLE CONFUSED AT ALL THE MANEUVERING THE JET WAS MAKING. AFTER THE JET PASSED OFF OUR L SIDE AT WINDOW LEVEL I DID NOT FEEL IT WAS CLOSE ENOUGH TO WARRANT EVEN AN EXPLANATION TO THE PAX. I ALSO DO NOT THINK ATC DID ANYTHING UNSAFE OR INAPPROPRIATE.

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.

TCASII. Intruder traffic reported by ATC and flight crew had it visually, but the traffic was descending and reporter said it descended below their altitude when suddenly it started a climb. Reporter was confused why the traffic started a climb out of a descent. Traffic was never closer than 2 mi.