Heading and altitude misinterp.

Attributes
ACN	292455
Time
Date	199412
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : iiu
State Reference	KY
Altitude	msl bound lower : 26000 msl bound upper : 27000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zid
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 121
Flight Phase	cruise other
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	DC-9 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 3 flight time total : 350
ASRS Report	292455
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : overshoot conflict : airborne less severe non adherence : required legal separation non adherence : clearance other spatial deviation
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	controller : issued new clearance flight crew : took evasive action
Consequence	faa : investigated
Miss Distance	horizontal : 9000 vertical : 900
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Operational Error Pilot Deviation

Narrative:

Aircraft X was northbound and inbound to ind. Aircraft Y departed cvg climbing over iiu VOR. Aircraft Y initially cleared to climb and maintain FL250 and acknowledged correctly. Subsequent clearance to aircraft Y was 'fly heading 270' direct pxv when able rest unchanged. Aircraft Y read back climbing 270 direct pxv. TCASII RA's issued by both aircraft and FAA standard separation was lost. Paramount to this situation was aircraft Y's improper readback of the clearance. At altitudes above 17000 ft all ATC altitude clrncs will be preceded by the words 'flight level.' if aircraft Y had read back the clearance including the altitude indicators 'flight level' the controller would have caught the error and separation could have been maintained. Contributing to the situation was assigning a heading that could be mistaken for an altitude. Although a heading of 270 degrees was a correct heading for pxv, a heading of 275 degrees or 265 degrees could have avoided confusion. ATC clrncs need to be read back completely. Controllers are trained to hear deviations for issued clrncs -- especially when clrncs affect separation. In this situation the controller only heard 270 direct pxv and separation was lost. Aircraft Y was requesting FL310 and aircraft X needed to be started down. Controller was using vertical separation until aircraft cleared.

Original NASA ASRS Text

Title: HDG AND ALT MISINTERP.

Narrative: ACFT X WAS NBOUND AND INBOUND TO IND. ACFT Y DEPARTED CVG CLBING OVER IIU VOR. ACFT Y INITIALLY CLRED TO CLB AND MAINTAIN FL250 AND ACKNOWLEDGED CORRECTLY. SUBSEQUENT CLRNC TO ACFT Y WAS 'FLY HDG 270' DIRECT PXV WHEN ABLE REST UNCHANGED. ACFT Y READ BACK CLBING 270 DIRECT PXV. TCASII RA'S ISSUED BY BOTH ACFT AND FAA STANDARD SEPARATION WAS LOST. PARAMOUNT TO THIS SIT WAS ACFT Y'S IMPROPER READBACK OF THE CLRNC. AT ALTS ABOVE 17000 FT ALL ATC ALT CLRNCS WILL BE PRECEDED BY THE WORDS 'FLT LEVEL.' IF ACFT Y HAD READ BACK THE CLRNC INCLUDING THE ALT INDICATORS 'FLT LEVEL' THE CTLR WOULD HAVE CAUGHT THE ERROR AND SEPARATION COULD HAVE BEEN MAINTAINED. CONTRIBUTING TO THE SIT WAS ASSIGNING A HDG THAT COULD BE MISTAKEN FOR AN ALT. ALTHOUGH A HDG OF 270 DEGS WAS A CORRECT HDG FOR PXV, A HDG OF 275 DEGS OR 265 DEGS COULD HAVE AVOIDED CONFUSION. ATC CLRNCS NEED TO BE READ BACK COMPLETELY. CTLRS ARE TRAINED TO HEAR DEVS FOR ISSUED CLRNCS -- ESPECIALLY WHEN CLRNCS AFFECT SEPARATION. IN THIS SIT THE CTLR ONLY HEARD 270 DIRECT PXV AND SEPARATION WAS LOST. ACFT Y WAS REQUESTING FL310 AND ACFT X NEEDED TO BE STARTED DOWN. CTLR WAS USING VERT SEPARATION UNTIL ACFT CLRED.

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.