Clearance confusion near burley, identification.

Attributes
ACN	479175
Time
Date	200007
Day	Mon
Local Time Of Day	1801 To 2400
Place
State Reference	ID
Altitude	msl bound lower : 29900 msl bound upper : 31000
Environment
Flight Conditions	Mixed VMC
Weather Elements	Turbulence
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zlc.artcc
Operator	common carrier : air carrier
Make Model Name	B727 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other vortac
Flight Phase	cruise : enroute altitude change
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 220 flight time total : 27000 flight time type : 18000
ASRS Report	479125
Person 2
Affiliation	company : air carrier
Function	controller : local
Qualification	pilot : atp
Experience	flight time last 90 days : 210 flight time total : 11050 flight time type : 11050
ASRS Report	479200
Events
Anomaly	altitude deviation : excursion from assigned altitude other anomaly other
Independent Detector	other controllerb
Resolutory Action	controller : issued new clearance controller : issued advisory
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	Ambiguous

Narrative:

We were arriving in the slc area from pdx at FL310 and in light turbulence. I requested FL290. The controller said 'stand by' then gave us clearance to FL270. Both I and the first officer clearly heard the clearance, entered FL270 in the altitude alerter, pointed to it, and I read back the clearance. As we descended through FL299, the controller said 'air carrier call sign, say your altitude.' I said FL299 descending to FL270. He said he had not given us clearance to FL270 and to maintain FL290. I said 'if you didn't then there must have been a very poor transmission, because I acknowledged the clearance before we started down.' obviously, he either mistakenly used our flight number in error, or both I and the first officer misheard the clearance, or there may have been some kind of 'talk-over' problem with simultaneous xmissions. I think we should pursue technology that would warn controllers of simultaneous xmissions.

Original NASA ASRS Text

Title: CLRNC CONFUSION NEAR BURLEY, ID.

Narrative: WE WERE ARRIVING IN THE SLC AREA FROM PDX AT FL310 AND IN LIGHT TURB. I REQUESTED FL290. THE CTLR SAID 'STAND BY' THEN GAVE US CLRNC TO FL270. BOTH I AND THE FO CLRLY HEARD THE CLRNC, ENTERED FL270 IN THE ALT ALERTER, POINTED TO IT, AND I READ BACK THE CLRNC. AS WE DSNDED THROUGH FL299, THE CTLR SAID 'ACR CALL SIGN, SAY YOUR ALT.' I SAID FL299 DSNDING TO FL270. HE SAID HE HAD NOT GIVEN US CLRNC TO FL270 AND TO MAINTAIN FL290. I SAID 'IF YOU DIDN'T THEN THERE MUST HAVE BEEN A VERY POOR XMISSION, BECAUSE I ACKNOWLEDGED THE CLRNC BEFORE WE STARTED DOWN.' OBVIOUSLY, HE EITHER MISTAKENLY USED OUR FLT NUMBER IN ERROR, OR BOTH I AND THE FO MISHEARD THE CLRNC, OR THERE MAY HAVE BEEN SOME KIND OF 'TALK-OVER' PROB WITH SIMULTANEOUS XMISSIONS. I THINK WE SHOULD PURSUE TECHNOLOGY THAT WOULD WARN CTLRS OF SIMULTANEOUS XMISSIONS.

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.