An air carrier medium large transport descended in response to a TCASII command.

Attributes
ACN	243275
Time
Date	199306
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : zdc
State Reference	DC
Altitude	msl bound lower : 26700 msl bound upper : 27000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc tower : lga
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	climbout : intermediate altitude cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : cfi pilot : atp
Experience	flight time last 90 days : 150 flight time total : 8000 flight time type : 5000
ASRS Report	243275
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : overshoot conflict : airborne less severe non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : took evasive action flight crew : returned to intended course or assigned course
Consequence	Other
Miss Distance	horizontal : 7000 vertical : 700
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We were descending to FL270. As the first officer initiated the level off the TCASII gave us an RA and commanded an increased rate of descent. At the same time, center was trying to advise us about the traffic. Since center and the TCASII were talking at the same time, I was unable to hear what center was saying. The first officer started to follow the TCASII command and by the time I commanded him to level off we were 200 ft below our assigned altitude. Center then advised us they had an altitude 'hit' on us and that the other traffic was at FL260. I didn't find out the status of the other traffic, but I can only imagine they must have been climbing to their assigned altitude as our TCASII called for a maximum rate descent (in excess of 4000 FPM). I believe if we had followed the TCASII recommendation, this would have resulted in a near miss. I don't remember the exact time and position of this occurrence, only that we were in ZDC airspace on or near J55 on a trip from fll to ewr.

Original NASA ASRS Text

Title: AN ACR MLG DSNDED IN RESPONSE TO A TCASII COMMAND.

Narrative: WE WERE DSNDING TO FL270. AS THE FO INITIATED THE LEVEL OFF THE TCASII GAVE US AN RA AND COMMANDED AN INCREASED RATE OF DSCNT. AT THE SAME TIME, CTR WAS TRYING TO ADVISE US ABOUT THE TFC. SINCE CTR AND THE TCASII WERE TALKING AT THE SAME TIME, I WAS UNABLE TO HEAR WHAT CTR WAS SAYING. THE FO STARTED TO FOLLOW THE TCASII COMMAND AND BY THE TIME I COMMANDED HIM TO LEVEL OFF WE WERE 200 FT BELOW OUR ASSIGNED ALT. CTR THEN ADVISED US THEY HAD AN ALT 'HIT' ON US AND THAT THE OTHER TFC WAS AT FL260. I DIDN'T FIND OUT THE STATUS OF THE OTHER TFC, BUT I CAN ONLY IMAGINE THEY MUST HAVE BEEN CLBING TO THEIR ASSIGNED ALT AS OUR TCASII CALLED FOR A MAX RATE DSCNT (IN EXCESS OF 4000 FPM). I BELIEVE IF WE HAD FOLLOWED THE TCASII RECOMMENDATION, THIS WOULD HAVE RESULTED IN A NEAR MISS. I DON'T REMEMBER THE EXACT TIME AND POS OF THIS OCCURRENCE, ONLY THAT WE WERE IN ZDC AIRSPACE ON OR NEAR J55 ON A TRIP FROM FLL TO EWR.

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.