Altitude deviation and potential conflict.

Attributes
ACN	145543
Time
Date	199005
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : atl
State Reference	GA
Altitude	msl bound lower : 23700 msl bound upper : 24000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : ztl
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	arrival other arrival star : star
Flight Plan	IFR
Aircraft 2
Operator	other
Make Model Name	Fighter
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : flight engineer pilot : commercial pilot : atp
Experience	flight time last 90 days : 300 flight time total : 12000 flight time type : 250
ASRS Report	154543
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	other controllera other flight crewa
Resolutory Action	controller : issued new clearance flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 6000 vertical : 700
Supplementary
Primary Problem	Ambiguous
Air Traffic Incident	Pilot Deviation Operational Error other

Narrative:

On sinca STAR into atl cleared direct canuk 128/40 (atl), not over dublin VOR on STAR. We were cleared from FL350 to FL240. In descent, center slowed us to 280 KTS. Atl was landing to the west so we had programmed in canuk 12000' and 250 KTS (atl 128/40). Our descent had us on the calculated descent path which we varied, as compared to the DME use 3 mi for every 1000' we need to lose. We were expecting the controller to give us canuk 250 KTS, 12000'. He came on and gave us canuk 250 KTS and 12000'. At 25000' he pointed a flight of 2 fgts at 23000', which we then questioned the altitude cleared to. We leveled at 23700'. We also told the controller we had the fgt's in sight the whole time. When we questioned the altitude, he said, 'I said expect 12000, 250 at canuk,' which neither I nor the copilot heard. At that time he cleared us to canuk 12000' and 250 KTS. We had to use maximum speed plus speed brake to make the restriction, which was very comfortable. We knew canuk 250 KTS, 12000' was a restriction because it's on the STAR--so to say expect, followed by the restriction, we may have blocked out 'expect' because we knew we had to keep descending to make the restriction.

Original NASA ASRS Text

Title: ALT DEVIATION AND POTENTIAL CONFLICT.

Narrative: ON SINCA STAR INTO ATL CLRED DIRECT CANUK 128/40 (ATL), NOT OVER DUBLIN VOR ON STAR. WE WERE CLRED FROM FL350 TO FL240. IN DSNT, CENTER SLOWED US TO 280 KTS. ATL WAS LNDG TO THE W SO WE HAD PROGRAMMED IN CANUK 12000' AND 250 KTS (ATL 128/40). OUR DSNT HAD US ON THE CALCULATED DSNT PATH WHICH WE VARIED, AS COMPARED TO THE DME USE 3 MI FOR EVERY 1000' WE NEED TO LOSE. WE WERE EXPECTING THE CTLR TO GIVE US CANUK 250 KTS, 12000'. HE CAME ON AND GAVE US CANUK 250 KTS AND 12000'. AT 25000' HE POINTED A FLT OF 2 FGTS AT 23000', WHICH WE THEN QUESTIONED THE ALT CLRED TO. WE LEVELED AT 23700'. WE ALSO TOLD THE CTLR WE HAD THE FGT'S IN SIGHT THE WHOLE TIME. WHEN WE QUESTIONED THE ALT, HE SAID, 'I SAID EXPECT 12000, 250 AT CANUK,' WHICH NEITHER I NOR THE COPLT HEARD. AT THAT TIME HE CLRED US TO CANUK 12000' AND 250 KTS. WE HAD TO USE MAX SPD PLUS SPD BRAKE TO MAKE THE RESTRICTION, WHICH WAS VERY COMFORTABLE. WE KNEW CANUK 250 KTS, 12000' WAS A RESTRICTION BECAUSE IT'S ON THE STAR--SO TO SAY EXPECT, FOLLOWED BY THE RESTRICTION, WE MAY HAVE BLOCKED OUT 'EXPECT' BECAUSE WE KNEW WE HAD TO KEEP DSNDING TO MAKE THE RESTRICTION.

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.