Sunday, April 8, 2012

A Turbulent Flight

"Never seen that before." That isn't something you necessarily want to have your pilot say. Its also not something you necessarily want to think when you are the pilot! What I saw wasn't all that amazing, just not something I've seen before.

I flew down to San Luis Obispo (SBP) today to visit an old friend of mine. I was going to bring my daughter with me, meet up with my friend, fly her on a brief sight seeing flight, and then fly home. My friend is really excited about flying and I really wanted to finally have a chance to show a non-pilot how cool it is to fly. Plans change however. Starting last night the "little voice" was telling me my daughter shouldn't come. That was strange.. usually I get tips that I shouldn't fly, not not to take specific people with me. OK, I thought, she'd rather hang out at home with friends anyway. She jumped at the opportunity to not take the trip with me.

I flew down to SBP at 3500 feet, there were headwinds forecast at all altitudes but they were slower at lower altitudes. I had no problem on the way there. It was hazy with a good headwind but smooth. On the way, however, the little voice then told me, don't take my friend for a flight. This was harder to listen to. I figured it had been a long time since I'd flown, it was hazy and likely to be a little turbulent in the areas right around SBP so maybe it wouldn't be a good day to take her for a flight. So after I landed instead of going for a flight we had lunch and I showed her the plane. We talked a bit about family and friends and life. It was good.

It was time to go home. I checked the weather on DUATs to supplement the weather briefing I got this morning and nothing looked different. No hazardous conditions or very strong winds at my altitude. I took off and encountered some gusts immediately after take off. No matter, I expected some roughness as the winds were picking up over the hills. I expected that to stop when I got up to cruise altitude of 4500. It didn't. It got worse and worse. I had flight following and no one else was reporting turbulence, but I was sure feeling it. I has power set for a cruise speed of 115 knots and saw on the GPS I was averaging a ground speed of 125 knots or so. The plane would settle for a minute or two and then suddenly it was shoved left or right or up or down. The ASI would read 120 kts, then 100, then 115 again. I decided to slow down to maneuver speed. I didn't know how bad this would get.

I kept my left hand lightly on the yolk and put my right hand on the ledge of the dash. That way when the bigger bumps hit I could grab the dash instead of putting any extra pressure on the yolk beyond keeping the wings level. I considered climbing higher but the winds at higher altitudes were predicted to be stronger. I tried to just remain level and at a reasonable speed. Reminding myself my CFI wouldn't consider this to be "moderate" turbulence, though I sure did. I was glad that my daughter wasn't with me and glad I didn't take my friend for a ride through this. I was able to focus on flying the plane.

I was considering asking ATC for some information on the winds at higher levels.. or at least making a pilot report about what I was experiencing. It was then that I saw an unwelcome sight. VOLTS the annunciator light flashed. Just a brief flicker. I decided I must have imagined it. A couple bounces later I saw it again. VOLTS. Damn. Another alternator failure. I did not need this. I tried the usual routine, reset alternator, nothing. I shut down some of the avionics and the VOLTs light went away... for a few minutes. VOLTS. VOLTS. VOLTS. Fine. I knew what to do. I contacted ATC and cancelled flight following. I told them I was having problems with the alternator and was going to shut down my com gear. The controller asked if I needed assistance. I said no. I'd dealt with this particular issue before.

I was approaching King City now. I considered briefly landing there but discarded the idea. I knew I could fly back to RHV without VOR or GPS because I've flown this route many times. I got one last read on the heading to Salinas off the VOR because of the haze, then shut down the avionics bus. The VOLTS light turned off.  At this point I was wondering why the "little voice" didn't tell me not to take this flight! I guessed it must be another one of those great learning experiences that I'll survive and learn from. 

I was trying to maintain the appropriate VFR cruise altitude but there were strong up and down drafts. I found myself climbing over 500 fpm with the nose pointed down. I knew no free lift without free down. Sure enough, I got caught in a strong downdraft... all of the sudden the ASI was reading 120 knots (with a power setting for 105 knots) and I was flying down, fast. I pulled power back to 1500 rpm and managed the airspeed as well as I could. I didn't want to be flying in the "yellow arc" in this rough air. That's when I saw it... the VSI was pegged all the way to the right, showing the max descent rate it could show. I'd never seen that before! I was doing the best I could. I had to wait it out.

As quickly as it started I was out of the downdraft. I brought power back up to the "green arc" and decided I'd had enough of the bouncing. I was going to try a lower altitude. I bounced and jolted my way down to 3000 ft. The air smoothed. I breathed a sigh of release, re-leaned the plane and settled into cruise for the remainder of the trip home.

I finished the flight with only a couple other relatively minor bumps at the usual spots over the hills between Salinas and Hollister and on approach for RHV. I turned on one radio and the transponder in time to do the 10 mile call to RHV and did a normal approach and landing.

I was amazed at how well I kept my heading through all of the bouncing with no GPS or VOR to help guide me. I thought about how it is likely to be turbulent in clouds when flying in IFR. I sure hope I don't have to feel that too often. I'm sure five years from now a flight in turbulence like that won't bother me so much. Today it bothered me, but I handled it. After I landed I went online and looked for any sign that I should have expected what I encountered. Winds were still what was predicted in the morning. No strong winds from different directions at different layers. No AIRMETs for turbulence... nothing that I could see to indicate I should expect almost moderate turbulence at 4500 feet.

I can't say that return flight was fun, but it helped me gain some confidence that I can handle unexpected situations pretty well. And, I'm pretty amazed at how smart that "little voice" is. I'm going to ask my CFI some non IFR related questions this week... :)

  • Another pilot from my airport reports the ride at 8500 feet was calm. Would it have been smart to climb more to try to find a smoother ride? I had plenty of fuel for a climb. 
  • I double checked the VSI on that plane, when the VSI is pegged all the way to the right that means at least a 2000 fpm descent (or ascent depending on your direction of travel). 

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