Medium large transport descends without clearance.

Attributes
ACN	147479
Time
Date	199006
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : fll
State Reference	FL
Altitude	msl bound lower : 13500 msl bound upper : 15000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zma
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	climbout : intermediate altitude descent other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Experience	flight time last 90 days : 150 flight time total : 9500
ASRS Report	147479
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : far non adherence : clearance
Independent Detector	other controllera other flight crewa
Resolutory Action	controller : issued new clearance
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

On climb out from fll to tpa, we checked in with ZMA out of 1100' and were cleared to FL230. There was a dissipating thundershower in our flight path. We determined if we were to reduce our rate of climb so as to pass below the overhang for a few mi, we would have a better ride. I requested a reduced rate of climb from center and we were cleared to do so. When it became obvious that we were too high to pass beneath the overhang the captain began a descent to do so before I could get clearance from center. We had descended from about 15000' through 13500' when center called and asked us if we were descending. We explained the situation to them and were instructed not to descend below 11000'. We complied and reinstated our climb after clearing the overhang. Our error was not communicating our intent to descend and making sure we ha clearance in a timely manner.

Original NASA ASRS Text

Title: MLG DESCENDS WITHOUT CLRNC.

Narrative: ON CLBOUT FROM FLL TO TPA, WE CHKED IN WITH ZMA OUT OF 1100' AND WERE CLRED TO FL230. THERE WAS A DISSIPATING THUNDERSHOWER IN OUR FLT PATH. WE DETERMINED IF WE WERE TO REDUCE OUR RATE OF CLB SO AS TO PASS BELOW THE OVERHANG FOR A FEW MI, WE WOULD HAVE A BETTER RIDE. I REQUESTED A REDUCED RATE OF CLB FROM CENTER AND WE WERE CLRED TO DO SO. WHEN IT BECAME OBVIOUS THAT WE WERE TOO HIGH TO PASS BENEATH THE OVERHANG THE CAPT BEGAN A DSNT TO DO SO BEFORE I COULD GET CLRNC FROM CENTER. WE HAD DSNDED FROM ABOUT 15000' THROUGH 13500' WHEN CENTER CALLED AND ASKED US IF WE WERE DSNDING. WE EXPLAINED THE SITUATION TO THEM AND WERE INSTRUCTED NOT TO DSND BELOW 11000'. WE COMPLIED AND REINSTATED OUR CLB AFTER CLRING THE OVERHANG. OUR ERROR WAS NOT COMMUNICATING OUR INTENT TO DSND AND MAKING SURE WE HA CLRNC IN A TIMELY MANNER.

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.