Heading track altitude deviation altitude excursion.

Attributes
ACN	272117
Time
Date	199405
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : mob
State Reference	AL
Altitude	msl bound lower : 21300 msl bound upper : 22000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : ztl
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 135
Flight Phase	cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 215 flight time total : 16000 flight time type : 5000
ASRS Report	272117
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 116 flight time total : 6400 flight time type : 1800
ASRS Report	271950
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other other spatial deviation
Independent Detector	other controllera
Resolutory Action	flight crew : became reoriented flight crew : returned to intended course or assigned course other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We were on 4TH day of 4 day trip. Minimum rest (legal). Left hotel that morning at AM40 so both of us were very tired. While on a heading of 140 degrees and altitude of 22000 ft, I heard center give us instructions to go to 180. The first officer answered, 'roger, flight X, 180.' I understood this as flight level 180 not heading 180. I changed the altitude select control to 18000 ft and began a slow descent. A short time later, center called back and said he showed us 700 ft low. I answered that he gave us a descent to flight level 180. He replied no, I meant turn to 180 degrees. I acknowledged and returned to 22000 ft and turned to a heading of 180 degrees. No conflict was noted. Supplemental information from acn 271950: cruising at 22000 ft 140 degree heading. ATC cleared us to 180 degree heading. I read back 180 degree heading. Captain (flying) changed altitude. Preselect to 18000 ft. Slow descent was started to 18000 ft, aircraft on 140 degree heading. Descent was not noticed by me (PNF). Captain took upon himself to change altitude. Preselect which was against company procedures. (PNF changes altitude preselect.) no conflict noted.

Original NASA ASRS Text

Title: HDG TRACK ALTDEV ALT EXCURSION.

Narrative: WE WERE ON 4TH DAY OF 4 DAY TRIP. MINIMUM REST (LEGAL). LEFT HOTEL THAT MORNING AT AM40 SO BOTH OF US WERE VERY TIRED. WHILE ON A HDG OF 140 DEGS AND ALT OF 22000 FT, I HEARD CTR GIVE US INSTRUCTIONS TO GO TO 180. THE FO ANSWERED, 'ROGER, FLT X, 180.' I UNDERSTOOD THIS AS FLT LEVEL 180 NOT HDG 180. I CHANGED THE ALT SELECT CTL TO 18000 FT AND BEGAN A SLOW DSCNT. A SHORT TIME LATER, CTR CALLED BACK AND SAID HE SHOWED US 700 FT LOW. I ANSWERED THAT HE GAVE US A DSCNT TO FLT LEVEL 180. HE REPLIED NO, I MEANT TURN TO 180 DEGS. I ACKNOWLEDGED AND RETURNED TO 22000 FT AND TURNED TO A HDG OF 180 DEGS. NO CONFLICT WAS NOTED. SUPPLEMENTAL INFO FROM ACN 271950: CRUISING AT 22000 FT 140 DEG HDG. ATC CLRED US TO 180 DEG HDG. I READ BACK 180 DEG HDG. CAPT (FLYING) CHANGED ALT. PRESELECT TO 18000 FT. SLOW DSCNT WAS STARTED TO 18000 FT, ACFT ON 140 DEG HDG. DSCNT WAS NOT NOTICED BY ME (PNF). CAPT TOOK UPON HIMSELF TO CHANGE ALT. PRESELECT WHICH WAS AGAINST COMPANY PROCS. (PNF CHANGES ALT PRESELECT.) NO CONFLICT NOTED.

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.