TCASII RA from traffic leveling 1000 ft below.

Attributes
ACN	189935
Time
Date	199109
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : bna
State Reference	TN
Altitude	msl bound lower : 26000 msl bound upper : 26250
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zme tower : mem
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Route In Use	enroute airway : zme
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : commercial pilot : atp pilot : instrument
Experience	flight time last 90 days : 200 flight time total : 13000 flight time type : 6000
ASRS Report	189935
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : commercial pilot : instrument
Experience	flight time last 90 days : 220 flight time total : 4100 flight time type : 100
ASRS Report	189815
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance 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	horizontal : 18000 vertical : 1250
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

This is not a near miss. Altitude deviation was only 250 ft so it was not an altitude bust. We were in cruise at FL260. Got a TCASII RA. Climbed 250 ft to comply. Then got clear of conflict. Problem with TCASII is that computer does not know an intruder is going to level off, so it issues an RA. This intruding aircraft leveled off at FL250. Solution is that we must have a climb rate at no more than 1000 FPM last 1000 ft. Then computers in both aircraft will not issue RA's.

Original NASA ASRS Text

Title: TCASII RA FROM TFC LEVELING 1000 FT BELOW.

Narrative: THIS IS NOT A NEAR MISS. ALT DEV WAS ONLY 250 FT SO IT WAS NOT AN ALT BUST. WE WERE IN CRUISE AT FL260. GOT A TCASII RA. CLBED 250 FT TO COMPLY. THEN GOT CLR OF CONFLICT. PROBLEM WITH TCASII IS THAT COMPUTER DOES NOT KNOW AN INTRUDER IS GOING TO LEVEL OFF, SO IT ISSUES AN RA. THIS INTRUDING ACFT LEVELED OFF AT FL250. SOLUTION IS THAT WE MUST HAVE A CLB RATE AT NO MORE THAN 1000 FPM LAST 1000 FT. THEN COMPUTERS IN BOTH ACFT WILL NOT ISSUE RA'S.

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.