Altitude deviation altitude excursion during TCASII RA.

Attributes
ACN	262270
Time
Date	199401
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : bwi airport : dca
State Reference	MD
Altitude	msl bound lower : 9200 msl bound upper : 10000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : dca
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	MD-80 Series (DC-9-80) Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	climbout : intermediate altitude cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 75 flight time total : 8000
ASRS Report	262270
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : less severe 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 : became reoriented flight crew : overcame equipment problem flight crew : returned to intended course or assigned course
Consequence	faa : reviewed incident with flight crew
Miss Distance	vertical : 1200
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

Flight from buf to dca, a B737-300. Crew of 5, 22 passenger. We were inbound to dca VOR on course 230 degrees, at 300 KTS, level at 10000 ft. VFR conditions. In contact with dca approach control 124.2. Clearance was 'direct to VOR, maintain 10000 ft.' 10 mi southwest of bwi, our TCASII emitted aural and instrumental warning 'don't climb.' threat target on our display was at 1 O'clock position and red. 1 or 2 seconds later, TCASII commanded 'descend' with the vsi showing red in the climb section and green dots in the descent section. My first officer saw an aircraft below us at 8000 ft or 9000 ft, and delayed leaving 10000 ft momentarily. TCASII then commanded 'increase descent.' I ordered the first officer to comply, and notified ATC that we were out of 10000 ft to comply with TCASII. TCASII alert stopped when we were at 9200 ft and the aircraft below us at our 1O O'clock position, below us, and moving away. Normal approach and landing accomplished at dca. After landing, called dca ATC. They indicated that separation was not lost with aircraft below us and there was no aircraft above us except for one at 13000 ft and level. Assistant chief pilot bwi called bwi approach control. Bwi ATC relayed to him that an md-80 climbing from bwi, cleared to 8000 ft, was climbing so fast that our TCASII interpreted it as a threat through our altitude. I believe the md-80 TCASII was telling them to 'climb' and with ours telling us to 'descend.' well, a potential, very bad situation might have happened. Fortunately, my first officer saw this aircraft below us and averted a close call. Our training with the TCASII unit specified that we are to comply with TCASII conflict warnings unless or until positive visual contact with the intruder provides a corrective course of action. It was looking up for an intruder that wasn't there and it was my first officer who was able to take the correct action. Bwi ATC indicated that this problem with bwi departures setting off false TCASII warnings for dca aircraft has happened before. I might add in closing, that this whole incident took place in about 15 seconds time.

Original NASA ASRS Text

Title: ALTDEV ALT EXCURSION DURING TCASII RA.

Narrative: FLT FROM BUF TO DCA, A B737-300. CREW OF 5, 22 PAX. WE WERE INBOUND TO DCA VOR ON COURSE 230 DEGS, AT 300 KTS, LEVEL AT 10000 FT. VFR CONDITIONS. IN CONTACT WITH DCA APCH CTL 124.2. CLRNC WAS 'DIRECT TO VOR, MAINTAIN 10000 FT.' 10 MI SW OF BWI, OUR TCASII EMITTED AURAL AND INSTRUMENTAL WARNING 'DON'T CLB.' THREAT TARGET ON OUR DISPLAY WAS AT 1 O'CLOCK POS AND RED. 1 OR 2 SECONDS LATER, TCASII COMMANDED 'DSND' WITH THE VSI SHOWING RED IN THE CLB SECTION AND GREEN DOTS IN THE DSCNT SECTION. MY FO SAW AN ACFT BELOW US AT 8000 FT OR 9000 FT, AND DELAYED LEAVING 10000 FT MOMENTARILY. TCASII THEN COMMANDED 'INCREASE DSCNT.' I ORDERED THE FO TO COMPLY, AND NOTIFIED ATC THAT WE WERE OUT OF 10000 FT TO COMPLY WITH TCASII. TCASII ALERT STOPPED WHEN WE WERE AT 9200 FT AND THE ACFT BELOW US AT OUR 1O O'CLOCK POS, BELOW US, AND MOVING AWAY. NORMAL APCH AND LNDG ACCOMPLISHED AT DCA. AFTER LNDG, CALLED DCA ATC. THEY INDICATED THAT SEPARATION WAS NOT LOST WITH ACFT BELOW US AND THERE WAS NO ACFT ABOVE US EXCEPT FOR ONE AT 13000 FT AND LEVEL. ASSISTANT CHIEF PLT BWI CALLED BWI APCH CTL. BWI ATC RELAYED TO HIM THAT AN MD-80 CLBING FROM BWI, CLRED TO 8000 FT, WAS CLBING SO FAST THAT OUR TCASII INTERPRETED IT AS A THREAT THROUGH OUR ALT. I BELIEVE THE MD-80 TCASII WAS TELLING THEM TO 'CLB' AND WITH OURS TELLING US TO 'DSND.' WELL, A POTENTIAL, VERY BAD SIT MIGHT HAVE HAPPENED. FORTUNATELY, MY FO SAW THIS ACFT BELOW US AND AVERTED A CLOSE CALL. OUR TRAINING WITH THE TCASII UNIT SPECIFIED THAT WE ARE TO COMPLY WITH TCASII CONFLICT WARNINGS UNLESS OR UNTIL POSITIVE VISUAL CONTACT WITH THE INTRUDER PROVIDES A CORRECTIVE COURSE OF ACTION. IT WAS LOOKING UP FOR AN INTRUDER THAT WASN'T THERE AND IT WAS MY FO WHO WAS ABLE TO TAKE THE CORRECT ACTION. BWI ATC INDICATED THAT THIS PROB WITH BWI DEPS SETTING OFF FALSE TCASII WARNINGS FOR DCA ACFT HAS HAPPENED BEFORE. I MIGHT ADD IN CLOSING, THAT THIS WHOLE INCIDENT TOOK PLACE IN ABOUT 15 SECONDS TIME.

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.