A DC9 air carrier flight crew reports misunderstanding with ZTL concerning an altitude assignment an...

Attributes
ACN	483603
Time
Date	200008
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	navaid : lgc.vortac
State Reference	GA
Altitude	msl single value : 22300
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : ztl.artcc
Operator	common carrier : air carrier
Make Model Name	DC-9 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other vortac
Flight Phase	descent : holding descent : intermediate altitude
Route In Use	arrival : holding pattern
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : multi engine
Experience	flight time last 90 days : 135 flight time total : 4800 flight time type : 550
ASRS Report	483603
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : cfi pilot : atp
Experience	flight time last 90 days : 200 flight time total : 9650 flight time type : 450
ASRS Report	483600
Events
Anomaly	altitude deviation : overshoot non adherence : clearance other anomaly other
Independent Detector	other controllerb other flight crewa other flight crewb other other : 4
Resolutory Action	controller : issued new clearance controller : provided flight assist none taken : detected after the fact
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	FAA ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Deviation

Narrative:

We had been cleared to hold over lgc VOR as published at FL280. Controller then started to step us down in altitude as we approached lgc. From FL240, we were cleared to FL220. I read back FL220, set in altitude alerter, and captain confirmed FL220. As the plane descended to FL220, we were asked our altitude at FL223. We told him. He said we had been cleared to FL230, but to continue down to FL210. There was an FAA observer on board in the jump seat. He confirmed we both said '220' but did not hear the original clearance. He contacted the center to follow up. No TCASII traffic was seen.

Original NASA ASRS Text

Title: A DC9 ACR FLC RPTS MISUNDERSTANDING WITH ZTL CONCERNING AN ALT ASSIGNMENT AND READBACK.

Narrative: WE HAD BEEN CLRED TO HOLD OVER LGC VOR AS PUBLISHED AT FL280. CTLR THEN STARTED TO STEP US DOWN IN ALT AS WE APCHED LGC. FROM FL240, WE WERE CLRED TO FL220. I READ BACK FL220, SET IN ALT ALERTER, AND CAPT CONFIRMED FL220. AS THE PLANE DSNDED TO FL220, WE WERE ASKED OUR ALT AT FL223. WE TOLD HIM. HE SAID WE HAD BEEN CLRED TO FL230, BUT TO CONTINUE DOWN TO FL210. THERE WAS AN FAA OBSERVER ON BOARD IN THE JUMP SEAT. HE CONFIRMED WE BOTH SAID '220' BUT DID NOT HEAR THE ORIGINAL CLRNC. HE CONTACTED THE CTR TO FOLLOW UP. NO TCASII TFC WAS SEEN.

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.

A DC9 air carrier flight crew reports misunderstanding with ZTL concerning an altitude assignment and readback.