Eclipse 500
Flight Crew Commercial; Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 45; Flight Crew Total 970; Flight Crew Type 45
Communication Breakdown; Other / Unknown
ATC Issue All Types; Deviation - Altitude Excursion From Assigned Altitude; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Weather / Turbulence
Flight Crew Regained Aircraft Control; Flight Crew Returned To Clearance
Aircraft; Human Factors; Procedure; Weather
I was descending on the FERN 5 arrival into VNY; single pilot; in an Eclipse light jet. An AIRMET for moderate turbulence below 12;000 FT was active for that area; but I had not encountered any actual turbulence; and had heard none mentioned or reported on the radio. I was on an IFR flight plan; located roughly 7 miles south west of the Fillmore (FIM) Vortac; and was descending to 5;000 FT on an assigned heading (vector) when I suddenly encountered moderate to severe turbulence. I am using the textbook definition here. Objects were tossed about the cabin; and it was difficult to operate the avionics because I couldn't keep my finger over the proper button. I was unable to maintain control of the airplane to within 'normal' tolerances. The autopilot disengaged due to the turbulence; a situation which I had not encountered before due to relatively low time in type. As a result of the autopilot disengaging coupled with the turbulence; it became difficult to maintain a heading or altitude; and I deviated from both my assigned heading and my assigned altitude by a significant amount (perhaps plus or minus 30 degrees of heading and plus 500 FT or minus 700 FT of altitude). Once I realized that the autopilot had disengaged; I took manual control of the aircraft; and was able to return to something close to my assigned heading and altitude. Once I descended below about 3;700 FT the turbulence abated; and the remainder of the flight was completed without incident.I report this incident primarily because ATC did not notify me in advance to expect the turbulence. When I reported it; and my inability to maintain heading or altitude; to ATC; he responded by saying that I should expect it to smooth out below 4;000 FT - which suggested to me that the Controller was aware of the turbulence but had chosen not to advise me of it before I encountered it. He also seemed surprised that the turbulence was causing me any real difficulty. I discovered that a PIREP was entered into the system as follows: CMA UA /OV VNY270015/TM 2225/FL040/TP CRJ2/TB MOD 040-050. My issue happened 10 minutes later; but the Controller chose not to advise me. The CRJ2 is a 50;000 lb. aircraft; and it reported moderate turbulence in the same area. My Eclipse is a 6;000 lb. airplane - the same level of turbulence is much worse in a smaller aircraft. I concluded that the Controller was not aware of the significance of reported moderate turbulence. The turbulence was reported as moderate by a transport jet; A CRJ2 likely headed for Burbank. Turbulence that is moderate for a CRJ2 is dangerous for a lighter aircraft. There are hills in that area; and if I had been in IMC and unable to maintain altitude; it could have resulted in a serious situation. I strongly suggest that the management of Socal TRACON revisit the training offered to their staff regarding turbulence; with a special focus on the fact that turbulence reported as moderate or severe by a large aircraft may be dangerous to a smaller aircraft. I also suggest that the TRACON revisit the training offered to their staff with an eye towards encouraging ATC personnel to make it a high priority to advise pilots when moderate or severe turbulence has been reported on their expected flight path. In the end; this event only resulted in a minor deviation from my assigned heading and altitude; with no damage done. It could have been more much serious - and I would have been much better prepared to deal with it as a pilot if ATC had given me a simple heads up a few minutes in advance.
EA50 pilot reports encountering severe turbulence during descent into VNY and suspects that ATC was aware of the turbulence and did not report it.