Air carrier descended to an occupied altitude resulting in less than standard separation.

Attributes
ACN	137399
Time
Date	199002
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : cys
State Reference	WY
Altitude	msl bound lower : 29000 msl bound upper : 31000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdv tracon : den
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
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent 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 : 200 flight time total : 9000 flight time type : 1000
ASRS Report	137399
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	altitude deviation : overshoot non adherence : published procedure non adherence : required legal separation
Independent Detector	atc equipment other atc equipment : unspecified other controllera
Resolutory Action	other
Consequence	faa : investigated
Miss Distance	horizontal : 24000 vertical : 1200
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

En route to den, while descending between FL324 and FL322 to FL310, center gave us another altitude. I thought it might have been FL230, which is a totally unusual altitude, but my first officer, when I asked him, responded FL290. So, I said, 'was it FL290 or FL320?' he said, 'FL290,' and responded to ATC den, 'air carrier X cleared 290.' ATC responded. At FL304 ATC responded, 'we show you at FL302. You were supposed to be at FL320.' we responded that we would return to FL320, but we were cleared to FL290. I called ATC den. They said that after review of tapes the alert had gone off, but it was due to controller giving company aircraft at FL310 descent to FL290 ahead of us, and then giving us FL310, which is why he tried to stop us at FL320.

Original NASA ASRS Text

Title: ACR DESCENDED TO AN OCCUPIED ALT RESULTING IN LESS THAN STANDARD SEPARATION.

Narrative: ENRTE TO DEN, WHILE DSNDING BTWN FL324 AND FL322 TO FL310, CENTER GAVE US ANOTHER ALT. I THOUGHT IT MIGHT HAVE BEEN FL230, WHICH IS A TOTALLY UNUSUAL ALT, BUT MY F/O, WHEN I ASKED HIM, RESPONDED FL290. SO, I SAID, 'WAS IT FL290 OR FL320?' HE SAID, 'FL290,' AND RESPONDED TO ATC DEN, 'ACR X CLRED 290.' ATC RESPONDED. AT FL304 ATC RESPONDED, 'WE SHOW YOU AT FL302. YOU WERE SUPPOSED TO BE AT FL320.' WE RESPONDED THAT WE WOULD RETURN TO FL320, BUT WE WERE CLRED TO FL290. I CALLED ATC DEN. THEY SAID THAT AFTER REVIEW OF TAPES THE ALERT HAD GONE OFF, BUT IT WAS DUE TO CTLR GIVING COMPANY ACFT AT FL310 DSCNT TO FL290 AHEAD OF US, AND THEN GIVING US FL310, WHICH IS WHY HE TRIED TO STOP US AT FL320.

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.