|37000 Feet||Browse and search NASA's
Aviation Safety Reporting System
|Local Time Of Day||0601 To 1200|
|Locale Reference||atc facility : odi|
|Altitude||msl bound lower : 18700|
msl bound upper : 19000
|Controlling Facilities||artcc : zmp|
|Operator||general aviation : corporate|
|Make Model Name||Small Transport, Low Wing, 2 Recip Eng|
|Flight Phase||cruise other|
|Function||flight crew : single pilot|
|Qualification||pilot : atp|
|Experience||flight time last 90 days : 100|
flight time total : 1700
flight time type : 960
|Function||controller : radar|
|Qualification||controller : radar|
|Anomaly||aircraft equipment problem : less severe|
altitude deviation : excursion from assigned altitude
inflight encounter : weather
|Independent Detector||other flight crewa|
|Resolutory Action||flight crew : exited adverse environment|
|Air Traffic Incident||other|
Was flying at FL190. Entered clouds, ragged clear ice formed rapidly. As I booted ice off autoplt (and aircraft) started to oscillate. I asked center for lower, met with 'stand by,' asked for an immediate descent (had lost about 200-300' by this time). Center cleared me to 15000'. Ice melted rapidly through 16000'. I was not aware of the problem with the autoplt until I disengaged it for the descent. Autoplt worked fine after ice melted. At the time the aircraft oscillation began, I had pitot, static and propeller deice on. I was a bit unnerved by the aircraft's action, so I didn't think to uncouple the autoplt when the motion started. First time I've ever experienced this type of event. A good lesson for the future is ice forms as fast in the summer at altitude as it does in the winter.
Original NASA ASRS Text
Title: SMT ICES UP, AUTOPLT GOES INTO OSCILLATION AND ACFT LOSES 300'.
Narrative: WAS FLYING AT FL190. ENTERED CLOUDS, RAGGED CLEAR ICE FORMED RAPIDLY. AS I BOOTED ICE OFF AUTOPLT (AND ACFT) STARTED TO OSCILLATE. I ASKED CENTER FOR LOWER, MET WITH 'STAND BY,' ASKED FOR AN IMMEDIATE DSCNT (HAD LOST ABOUT 200-300' BY THIS TIME). CENTER CLRED ME TO 15000'. ICE MELTED RAPIDLY THROUGH 16000'. I WAS NOT AWARE OF THE PROB WITH THE AUTOPLT UNTIL I DISENGAGED IT FOR THE DSCNT. AUTOPLT WORKED FINE AFTER ICE MELTED. AT THE TIME THE ACFT OSCILLATION BEGAN, I HAD PITOT, STATIC AND PROP DEICE ON. I WAS A BIT UNNERVED BY THE ACFT'S ACTION, SO I DIDN'T THINK TO UNCOUPLE THE AUTOPLT WHEN THE MOTION STARTED. FIRST TIME I'VE EVER EXPERIENCED THIS TYPE OF EVENT. A GOOD LESSON FOR THE FUTURE IS ICE FORMS AS FAST IN THE SUMMER AT ALT AS IT DOES IN THE WINTER.
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.