Descending B727 queried by ATC as to whether they are going to level at FL270 as their aircraft leaves FL250. Crew had never received FL270 clearance, but had received FL250 with a 'pilot's discretion to FL240.' query came along with a heading change and a TA.

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Attributes
ACN	394850
Time
Date	199802
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : sso
State Reference	NM
Altitude	msl bound lower : 24700 msl bound upper : 27000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zab
Operator	common carrier : air carrier
Make Model Name	B727 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	cruise other descent other
Route In Use	enroute : direct enroute : on vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	other : unknown
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : flight engineer pilot : commercial pilot : atp
Experience	flight time last 90 days : 240 flight time total : 9000 flight time type : 2400
ASRS Report	394850
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : commercial pilot : flight engineer pilot : instrument
Experience	flight time last 90 days : 200 flight time total : 13500 flight time type : 8000
ASRS Report	394704
Events
Anomaly	other anomaly other
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	other

Narrative:

Received descent clearance from FL310 to FL250 'now,' discretion to FL240. Center questioned our heading and asked us to turn 10 degrees left for traffic at our 2 O'clock. Passing FL247 we were asked by center if we were leveling at FL270. We said our actual altitude and that we understood clearance limit to be FL240. Our company and NASA callback have emphasized altdevs to the point that our SOP is redundant and thorough. I believe this is a case of an altitude clearance not received or acknowledged. Supplemental information from acn 394704: our redundant altitude awareness programs in the cockpit seem to be working well but can break down with failures in radio communication. In this case none of us heard or acknowledged a change in our altitude clearance. The controller did not repeat it when we did not acknowledge it and so each was assuming different information.

Original NASA ASRS Text

Title: DSNDING B727 QUERIED BY ATC AS TO WHETHER THEY ARE GOING TO LEVEL AT FL270 AS THEIR ACFT LEAVES FL250. CREW HAD NEVER RECEIVED FL270 CLRNC, BUT HAD RECEIVED FL250 WITH A 'PLT'S DISCRETION TO FL240.' QUERY CAME ALONG WITH A HDG CHANGE AND A TA.

Narrative: RECEIVED DSCNT CLRNC FROM FL310 TO FL250 'NOW,' DISCRETION TO FL240. CTR QUESTIONED OUR HDG AND ASKED US TO TURN 10 DEGS L FOR TFC AT OUR 2 O'CLOCK. PASSING FL247 WE WERE ASKED BY CTR IF WE WERE LEVELING AT FL270. WE SAID OUR ACTUAL ALT AND THAT WE UNDERSTOOD CLRNC LIMIT TO BE FL240. OUR COMPANY AND NASA CALLBACK HAVE EMPHASIZED ALTDEVS TO THE POINT THAT OUR SOP IS REDUNDANT AND THOROUGH. I BELIEVE THIS IS A CASE OF AN ALT CLRNC NOT RECEIVED OR ACKNOWLEDGED. SUPPLEMENTAL INFO FROM ACN 394704: OUR REDUNDANT ALT AWARENESS PROGRAMS IN THE COCKPIT SEEM TO BE WORKING WELL BUT CAN BREAK DOWN WITH FAILURES IN RADIO COM. IN THIS CASE NONE OF US HEARD OR ACKNOWLEDGED A CHANGE IN OUR ALT CLRNC. THE CTLR DID NOT REPEAT IT WHEN WE DID NOT ACKNOWLEDGE IT AND SO EACH WAS ASSUMING DIFFERENT INFO.

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.