December 1, 2006
"When a front is occluded, the weather is anyone's guess."
Those words, spoken by my instructor years ago, nagged me as my wife and I finished dinner in Hickory, North Carolina, where we had stopped for fuel. Now we were waiting out the weather before completing our trip back to Atlanta's Dekalb-Peachtree airport. Our landing at Hickory two hours earlier had been in darkness, rain, and turbulence, with the ceilings down to minimums. Gale-force winds had been blowing all day long up and down the East Coast at 3,000 feet and above. Over the southeast, a cold front was chasing a warm front ahead of it — an occlusion that had been generating rough weather all day in Georgia and the Carolinas. Looking out the window, I noticed the heavy downpours sweeping the restaurant parking lot, more evidence of the unsettled conditions above.
Around 8:30 p.m., a 50-mile corridor had opened up between storms across the northwestern corner of South Carolina. Thirty minutes later we were back in the air in our Bonanza A36 heading toward Greenville Spartanburg International airport.
Atlanta Center advised us about lines of storms on each side of our track, forming a gauntlet on our path. We agreed on a course that would traverse down the middle of the corridor before Center handed us off to Greer Approach. The approach controller continued to provide us weather updates and suggested headings to accommodate changes in the weather conditions.
We flew on autopilot as we entered a dense cloudbank when ATC advised us that our present heading would take us several miles east of the edge of some level two- and three storms. The controller mentioned that his radar looked OK at the moment, and he added that he would provide us other options if things got dicey. His remark got my attention, but since our Stormscope was clear 10 miles out in the direction we were heading, I believed we were probably in pretty good shape.
I glanced at the airspeed indicator only seconds later to discover a rapid airspeed increase into the yellow arc. We had entered a column of very fast rising air, and as the aircraft was accelerating upward, the autopilot commanded the aircraft to dive in order to maintain the preset altitude. I was shocked. I disconnected the autopilot, yanked back on the throttle, and pulled hard on the yoke to level off. We bled off some airspeed just before the aircraft was slammed sideways into an opposing air column that sent every loose object in the cabin flying. Our heads slammed against the headliner in spite of the fact that we were tightly belted in. We experienced more moments of lurches, yaws, climbs, and dives, while I focused on simply keeping the aircraft in a level attitude. Finally, the disturbing motion subsided, and we settled back into relatively smooth air. There had been no rain, no lightning, no hail, and no warning associated with this frightful encounter. The cause had been invisible on the controller's radar and our Stormscope.
In reflection, I realize that I carelessly set up my airplane for its worst-case scenario. I was motoring along on autopilot in bumpy clouds of unknown turbulence. When we encountered a sudden build-up of airspeed, well in excess of maneuvering speed, I was slow to recognize the danger and correct for it. We were lucky to escape damage from potentially hazardous turbulence and severe up- and downdrafts. I learned firsthand how conditions in the wedge between a fast-moving cold front and a lumbering warm front ahead of it can be an area of unpredictable, hazardous, and freaky weather. I made a few New Year's resolutions based on this experience.
Don't underestimate prognosis charts.
IFR at night can complicate the scenario — err on the very conservative side.
If rough weather is ahead, strap everything in before takeoff.
In bumpy IMC, especially in unpredictable conditions, fly the airplane by hand and try to anticipate events.
Know your airplane's maneuvering speeds at different weights.
ATC radar and onboard weather detection tools are invaluable resources, but it is important to understand the limitations of this equipment.
We experienced conditions that under more severe circumstances could have led to fatal in-flight structural failures. I am thankful for a sturdy airplane and lucky to have suffered no more than a bent ego for lapses in flight training basics that are now branded into my flying consciousness.
David Howe, AOPA 1321476, is a CFI and a retired business executive living in Atlanta. He owns a Bonanza A36 and has accumulated more than 1,400 hours over nine years.
You can find additional information about frontal weather phenomena at the following links:
Look for the latest installment of "Never Again," in the January issue of AOPA Pilot. Deteriorating visibility gets the upper hand of the pilot and his aircraft.
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