<< >> NASA ASRS Report 226415, November 1992

An air carrier light transport climbed in response to a TCASII alert in IMC. ATC gave the reporting light transport instructions to level at an altitude that had already been passed.

Attributes
ACN	226415
Time
Date	199211
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : dfw
State Reference	TX
Altitude	msl bound lower : 4300 msl bound upper : 5000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : dfw tower : mdw
Operator	common carrier : air carrier
Make Model Name	Light Transport, Low Wing, 2 Turboprop Eng
Navigation In Use	Other Other
Flight Phase	cruise other descent other
Route In Use	arrival other arrival star : star enroute : on vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 12000 flight time type : 3000
ASRS Report	226415
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
Independent Detector	aircraft equipment other aircraft equipment : unspecified other controllera other flight crewa
Resolutory Action	controller : issued new clearance flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 6000 vertical : 400
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Pilot Deviation other

Narrative:

Air carrier light transport was flying the acton 2 arrival into dfw, altitude 5000 ft, IAS 210 KTS. Radar vector heading. ATC 118.1 cleared air carrier light transport to descend to 3000 ft and slow to 190 KIAS. A descent of 1500 FPM was established and power set to establish this decelerating descent. As the aircraft passed 4500 ft, ATC cleared air carrier light transport to level at 4500 ft and gave TA 12 O'clock, 2 1/2 mi, 4000 ft. A climb attitude of 1900 FPM was commanded and climb power set. The aircraft began ascent at 4100 ft. Concurrently, a TCASII RA warning commanded a climb of 1750 FPM. The 1900 FPM climb was maintained until TCASII command ceased. The aircraft was leveled at 4600 ft. The ATC clearance for air carrier light transport was to descend and slow was read back to the controller, as was the level at 4500 ft clearance. Recommend ATC should verify/acknowledge readback to ensure that communicated clrncs reflect ATC intent.

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Original NASA ASRS Text

Title: AN ACR LTT CLBED IN RESPONSE TO A TCASII ALERT IN IMC. ATC GAVE THE RPTING LTT INSTRUCTIONS TO LEVEL AT AN ALT THAT HAD ALREADY BEEN PASSED.

Narrative: ACR LTT WAS FLYING THE ACTON 2 ARR INTO DFW, ALT 5000 FT, IAS 210 KTS. RADAR VECTOR HDG. ATC 118.1 CLRED ACR LTT TO DSND TO 3000 FT AND SLOW TO 190 KIAS. A DSCNT OF 1500 FPM WAS ESTABLISHED AND PWR SET TO ESTABLISH THIS DECELERATING DSCNT. AS THE ACFT PASSED 4500 FT, ATC CLRED ACR LTT TO LEVEL AT 4500 FT AND GAVE TA 12 O'CLOCK, 2 1/2 MI, 4000 FT. A CLB ATTITUDE OF 1900 FPM WAS COMMANDED AND CLB PWR SET. THE ACFT BEGAN ASCENT AT 4100 FT. CONCURRENTLY, A TCASII RA WARNING COMMANDED A CLB OF 1750 FPM. THE 1900 FPM CLB WAS MAINTAINED UNTIL TCASII COMMAND CEASED. THE ACFT WAS LEVELED AT 4600 FT. THE ATC CLRNC FOR ACR LTT WAS TO DSND AND SLOW WAS READ BACK TO THE CTLR, AS WAS THE LEVEL AT 4500 FT CLRNC. RECOMMEND ATC SHOULD VERIFY/ACKNOWLEDGE READBACK TO ENSURE THAT COMMUNICATED CLRNCS REFLECT ATC INTENT.

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.