Altitude excursion. Misunderstood communication.

Attributes
ACN	299020
Time
Date	199503
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : jax
State Reference	FL
Altitude	msl bound lower : 4600 msl bound upper : 5000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : jax tower : jax
Operator	common carrier : air taxi
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 135
Navigation In Use	Other Other
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air taxi
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 4800 flight time type : 1000
ASRS Report	299020
Person 2
Affiliation	company : air taxi
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	controller : issued new clearance flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

During approach to airport we were told to maintain 5000 ft and fly heading 360 degree vector for the visual runway 7. ATC called traffic as B737 also inbound to jax. We reported the B737 in sight and were told to follow him. The PF believed that ATC wanted a descent to the airport and started out of 5000 ft. At 4600 ft I asked the PF if we were cleared for the visual approach, he replied that he wasn't sure and stopped the descent. I called ATC and verified that we were cleared for the visual. After a short delay they cleared us for the visual and told us to maintain visual separation with the B737. It appeared that a trainee was on position at approach control. This, plus fatigue of flight crew, may have contributed to the situation.

Original NASA ASRS Text

Title: ALT EXCURSION. MISUNDERSTOOD COM.

Narrative: DURING APCH TO ARPT WE WERE TOLD TO MAINTAIN 5000 FT AND FLY HDG 360 DEG VECTOR FOR THE VISUAL RWY 7. ATC CALLED TFC AS B737 ALSO INBOUND TO JAX. WE RPTED THE B737 IN SIGHT AND WERE TOLD TO FOLLOW HIM. THE PF BELIEVED THAT ATC WANTED A DSCNT TO THE ARPT AND STARTED OUT OF 5000 FT. AT 4600 FT I ASKED THE PF IF WE WERE CLRED FOR THE VISUAL APCH, HE REPLIED THAT HE WASN'T SURE AND STOPPED THE DSCNT. I CALLED ATC AND VERIFIED THAT WE WERE CLRED FOR THE VISUAL. AFTER A SHORT DELAY THEY CLRED US FOR THE VISUAL AND TOLD US TO MAINTAIN VISUAL SEPARATION WITH THE B737. IT APPEARED THAT A TRAINEE WAS ON POS AT APCH CTL. THIS, PLUS FATIGUE OF FLC, MAY HAVE CONTRIBUTED TO THE SIT.

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.