<< >> NASA ASRS Report 199724, January 1992

Air carrier Y climb to occupied altitude had less than standard separation from air carrier X. System error. Air carrier X non compliance with ATC instructions failed to climb to new assigned altitude. Pilot deviation.

Attributes
ACN	199724
Time
Date	199201
Day	Sat
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : aus
State Reference	TX
Altitude	msl bound lower : 18000 msl bound upper : 18000
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Controlling Facilities	artcc : zhu tower : dtw
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	climbout : intermediate altitude
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller military : 4 controller non radar : 3 controller radar : 3
ASRS Report	199724
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : clearance non adherence : required legal separation non adherence : published procedure
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	faa : investigated
Miss Distance	horizontal : 24000 vertical : 800
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error Pilot Deviation

Narrative:

Air carrier X departed austin wbound and checked on level at 10000 ft. I climbed him to 11000 ft then to 15000 ft when he entered my airspace. Air carrier Y checked on northbound out of san antonio leaving 11000 ft for 13000 ft. I told him 'roger' and let him level off to keep him under and eventually ladder him up under air carrier X. I was already laddering air carrier X under a northbound air carrier. I climbed air carrier Y to FL180. I climbed air carrier Y to FL180 thinking I had issued 17000 ft. Later I climbed air carrier X to FL230. When I say he never left FL180, I went back and stopped air carrier Y at 17000, but air carrier Y was already passing behind air carrier X. Air carrier Y said he was out of 17400 ft. He asked if I wanted him to go back down and I said yes. He said he was out of 17700 ft. At no time did I notice air carrier Y descend back down.

Related reports:

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• Air carrier X had less than standard separation from air car...

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Original NASA ASRS Text

Title: ACR Y CLB TO OCCUPIED ALT HAD LTSS FROM ACR X. SYS ERROR. ACR X NON COMPLIANCE WITH ATC INSTRUCTIONS FAILED TO CLB TO NEW ASSIGNED ALT. PLTDEV.

Narrative: ACR X DEPARTED AUSTIN WBOUND AND CHKED ON LEVEL AT 10000 FT. I CLBED HIM TO 11000 FT THEN TO 15000 FT WHEN HE ENTERED MY AIRSPACE. ACR Y CHKED ON NBOUND OUT OF SAN ANTONIO LEAVING 11000 FT FOR 13000 FT. I TOLD HIM 'ROGER' AND LET HIM LEVEL OFF TO KEEP HIM UNDER AND EVENTUALLY LADDER HIM UP UNDER ACR X. I WAS ALREADY LADDERING ACR X UNDER A NBOUND ACR. I CLBED ACR Y TO FL180. I CLBED ACR Y TO FL180 THINKING I HAD ISSUED 17000 FT. LATER I CLBED ACR X TO FL230. WHEN I SAY HE NEVER LEFT FL180, I WENT BACK AND STOPPED ACR Y AT 17000, BUT ACR Y WAS ALREADY PASSING BEHIND ACR X. ACR Y SAID HE WAS OUT OF 17400 FT. HE ASKED IF I WANTED HIM TO GO BACK DOWN AND I SAID YES. HE SAID HE WAS OUT OF 17700 FT. AT NO TIME DID I NOTICE ACR Y DSND BACK DOWN.

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.