Light transport encounters turbulence at top of descent, deviates from clearance.

Attributes
ACN	113379
Time
Date	198905
Day	Wed
Local Time Of Day	0001 To 0600
Place
Locale Reference	atc facility : dsm
State Reference	IA
Altitude	msl bound lower : 34000 msl bound upper : 35000
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zmp
Operator	common carrier : air taxi
Make Model Name	Light Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air taxi
Function	flight crew : captain oversight : pic
Qualification	pilot : cfi pilot : atp
Experience	flight time last 90 days : 175 flight time total : 3256 flight time type : 1040
ASRS Report	113379
Person 2
Affiliation	company : air taxi
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude inflight encounter : weather non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	flight crew : exited adverse environment flight crew : overcame equipment problem
Consequence	Other
Supplementary
Primary Problem	Weather
Air Traffic Incident	Pilot Deviation

Narrative:

The problems of this situation arose from inadvertently penetrating an area of severe thunderstorms during the initial letdown to dsm airport. We were cleared to descend out of 35,000'. When we began the descent, mod to severe turbulence was encountered with altitude gains and losses of 500-1000'. Mod precipitation was also encountered at this time and radio communications became intermittent. A climb was established to regain communications, get above the WX, communications were reestablished and the trip continued on to the next destination without difficulty. The main problem and reason for this form, was the loss of communications. I feel if aircraft certified for IFR and known icing conditions were also required to show adequate communications ability in mod precipitation, this problem could have been avoided.

Original NASA ASRS Text

Title: LTT ENCOUNTERS TURBULENCE AT TOP OF DESCENT, DEVIATES FROM CLRNC.

Narrative: THE PROBLEMS OF THIS SITUATION AROSE FROM INADVERTENTLY PENETRATING AN AREA OF SEVERE TSTMS DURING THE INITIAL LETDOWN TO DSM ARPT. WE WERE CLRED TO DSND OUT OF 35,000'. WHEN WE BEGAN THE DSCNT, MOD TO SEVERE TURBULENCE WAS ENCOUNTERED WITH ALT GAINS AND LOSSES OF 500-1000'. MOD PRECIPITATION WAS ALSO ENCOUNTERED AT THIS TIME AND RADIO COMS BECAME INTERMITTENT. A CLIMB WAS ESTABLISHED TO REGAIN COMS, GET ABOVE THE WX, COMS WERE REESTABLISHED AND THE TRIP CONTINUED ON TO THE NEXT DEST WITHOUT DIFFICULTY. THE MAIN PROBLEM AND REASON FOR THIS FORM, WAS THE LOSS OF COMS. I FEEL IF ACFT CERTIFIED FOR IFR AND KNOWN ICING CONDITIONS WERE ALSO REQUIRED TO SHOW ADEQUATE COMS ABILITY IN MOD PRECIPITATION, THIS PROBLEM COULD HAVE BEEN AVOIDED.

Data retrieved from NASA's ASRS site as of August 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.