Air carrier medium large transport altitude deviation excursion from clearance altitude in response ...

Attributes
ACN	190408
Time
Date	199109
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : gvf
State Reference	VA
Altitude	msl bound lower : 29000 msl bound upper : 29500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc tower : dfw
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 : zdc
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	climbout : intermediate altitude cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : cfi pilot : instrument pilot : atp pilot : commercial
Experience	flight time last 90 days : 120 flight time total : 8000
ASRS Report	190408
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : returned to intended course or assigned course
Consequence	Other
Miss Distance	horizontal : 0 vertical : 1500
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Altitude deviation due to TCASII resolution command at cruise altitude level flight 29000 ft. TCASII suddenly issued a TA swiftly followed by an RA of 'climb, climb, now'. Without any traffic in sight we could only comply. With the altitude of 29500 we sighted an air carrier Y medium large transport just below the nose but still at least 1000 ft below. As air carrier Y passed under, the TCASII checked our climb and we descended down to cruise altitude. ATC was questioned about the traffic and they confirmed that it was at 28000 ft. It is our feeling that the medium large transport's high rate of climb during its final 1000 ft of its climb to level off was interpreted as a threat by the TCASII and an advisory was issued even though separation was adequate.

Original NASA ASRS Text

Title: ACR MLG ALT DEV EXCURSION FROM CLRNC ALT IN RESPONSE TO TCASII RA.

Narrative: ALT DEV DUE TO TCASII RESOLUTION COMMAND AT CRUISE ALT LEVEL FLT 29000 FT. TCASII SUDDENLY ISSUED A TA SWIFTLY FOLLOWED BY AN RA OF 'CLB, CLB, NOW'. WITHOUT ANY TFC IN SIGHT WE COULD ONLY COMPLY. WITH THE ALT OF 29500 WE SIGHTED AN ACR Y MLG JUST BELOW THE NOSE BUT STILL AT LEAST 1000 FT BELOW. AS ACR Y PASSED UNDER, THE TCASII CHKED OUR CLB AND WE DSNDED DOWN TO CRUISE ALT. ATC WAS QUESTIONED ABOUT THE TFC AND THEY CONFIRMED THAT IT WAS AT 28000 FT. IT IS OUR FEELING THAT THE MLG'S HIGH RATE OF CLB DURING ITS FINAL 1000 FT OF ITS CLB TO LEVEL OFF WAS INTERPRETED AS A THREAT BY THE TCASII AND AN ADVISORY WAS ISSUED EVEN THOUGH SEPARATION WAS ADEQUATE.

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.

Air carrier medium large transport altitude deviation excursion from clearance altitude in response to TCASII RA.