Skyhawk 172/Cutlass 172
Flight Crew Commercial; Flight Crew Flight Instructor; Flight Crew Instrument
Flight Crew Last 90 Days 180; Flight Crew Total 510; Flight Crew Type 430
Deviation - Altitude Excursion From Assigned Altitude; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Provided Assistance; Flight Crew Returned To Clearance; Flight Crew Took Evasive Action
Weather
On V460 about 15 miles from JLI VOR; ATC cleared us from KARRO to ESCON at 10;000 feet. As we proceeded along the route; I noticed our airspeed start to drop. Simultaneously; my student raised the nose to maintain altitude. He increased power to full. After about 10 seconds; we had lost 200 feet. I told Socal approach that we were encountering some downdrafts and were unable to maintain altitude at the moment. After another 10 seconds we were descending through 9;500 feet with the VSI reading approximately 1;800 fpm down. Approach asked if we had made it out of the downdraft; I told him that it appeared to be a mountain wave; and that we were in an extremely strong downdraft and we were unable to maintain our altitude. He told us to turn right heading 060 in an effort to get us out of the wave; but it only made matters worse. Seconds after we made the turn we were passing through 8;000 feet. Approach advised us of the terrain nearby; and that we were well below the MEA. We asked for a right turn to approximately 100; which he approved. As I had hoped; we were able to get into the rising air from the mountain wave; and were able to climb back up to altitude. Almost. We got into another downdraft shortly thereafter. My student and I worked with approach to get clear of the turbulence and downdrafts. We were able to proceed without further incident. We went from 10;000 feet to just over 7;000 feet in about 2 minutes. Once in the sinking air; it was incredibly smooth. The winds were forecast to be out of the northeast at 30 knots; and there was no report of any windshear or downdrafts. The VFR sectional points out that severe turbulence and up/downdrafts can be encountered when high wind speeds are prevalent; but it's not mentioned on the IFR Low Enroute chart. Had that note been on the IFR chart; my student and I would've picked a different route. Also contributing was the fact that we both got online weather briefings. It would've been smarter to talk to a local weather briefer who could inform us of the possibility of the downdrafts along that route with the strong winds aloft. I have since begun more extensively reviewing VFR charts prior to flying IFR.
C172 instructor pilot reported extreme downdrafts in the vicinity of JLI VOR.