Wx Watch: Surviving the Scare

The worst has happened. Your plan to maintain visual separation from cloud buildups fell apart. After 20 nerve-wracking minutes of weaving around and through ever-darkening clouds, you never found a path to clear air. What looked like your last hope — squeezing through a narrow shaft of cloud-free sky toward a promising brightness — was instead a trap. The brightness was the sunlit flank of a towering cumulus cloud. And you just flew into it.

You should have turned around sooner, but thoughts of a 180-degree turn are relegated to second place as you fight to maintain control of the airplane in the wind shear, turbulence, and heavy rain of a thunderstorm cell. What to do?

Experts debate the best methods for riding out a thunderstorm penetration, but there's a consensus of sorts. Here are the main points to remember should you find yourself in forbidden territory:

Keep your cool. This sounds easy from your current perspective as a reader of this magazine, but it's central to your survival. The airspeed and altimeter are all over the place, the rain sounds like hail (maybe it is hail!), there are strong G-forces, lightning and thunder are all around, and you fear the worst. These are the sensations and trauma that you must endure in a thunderstorm. Sure, you're scared, but do your best to maintain control and a positive mental outlook. Others have survived thunderstorms, and you can too.

Let someone know. ATC, flight service, or flight watch ought to know what's happened. Ideally, you're on an IFR flight plan (or using VFR advisories/flight following) and already have an air traffic control frequency dialed into your com radio. If not, call up ATC, flight watch, or flight service and let them know what's going on. Personnel may be able to help guide you around the worst of the storm, using their ground-based Doppler weather radar. Of course, you have the option of using the emergency frequency — 121.5 MHz — for immediate attention and declaring an emergency.

Tighten your seat belt, and be sure loose items are stowed. Seat belt tension can be lost in a thunderstorm's chaos, so be sure it's tight. Even if you are cinched down, don't be surprised if your head meets the headliner in updrafts and downdrafts. If you haven't stowed or secured your luggage or other loose objects, you'll wish you had: They can become missiles in turbulence. Consider this an advertisement to put as much baggage as you can behind your cargo net (if you have one) or beneath your seats, or lash it down with seat belts, bungee nets, or other suitable methods. The last thing you need is for a tow bar to smack you over the head while you're struggling to keep the airplane upright.

Set power for maneuvering speed. Set aside some time in a practice session to learn the manifold pressure/rpm combination that will produce your airplane's V _A, or maneuvering speed. This is the airspeed that will prevent you from overstressing your airframe in turbulence. Fly at the appropriate speed for your airplane's actual weight (V _A goes up at heavier weights and is lower at lighter weights) and you'll be able to use full-control deflections without fear of overstress. The downside: At V _A, you'll stall before you'll overstress the airframe — something else you can do without in a storm cell. Should you enter a thunderstorm, immediately select the power combination for V _A. Knowing it ahead of time keeps you from juggling the engine controls, and frees you to focus on flying.

Fly attitude, not altitude. Whatever you do, don't chase the airspeed indicator or altimeter. Both instruments will be fluctuating wildly, and you'll end up past redline, stalling, or overstressing the airframe if you try to maintain a predetermined airspeed or altitude. Instead, do your best to keep the attitude indicator's airplane symbol as straight and level as you can. Ride out the bumps and accept altitude excursions. If you're talking with ATC, advise them that you can't maintain your altitude and will need a block of altitude for your uncommanded climbs and descents. Don't be bashful — ask for a 10,000-foot altitude block if you feel this will be necessary.

Hold your heading. Try to hold your heading, that is. This will help to keep your wings level — an essential ingredient to preventing an overbank/overspeed condition.

Don't attempt to reverse course. Once in a storm, a 180-degree turn may prove disastrous if turbulence or wind shear rolls you over into a steep bank or upset. There's debate on this point. Some say, "Go ahead and turn around, it's the quickest way out, and you may avoid a stronger cell ahead." Others argue that the shortest route out of a thunderstorm is to maintain your course, claiming that most thunderstorms are only a few miles wide and that you'll fly out the other side in a few minutes. The choice is up to you. There are good points on both sides of this argument. Ideally, you'll have information from ATC, flight watch, or flight service as to the least dangerous areas of convection.

If you're using one, disengage the autopilot. There are conflicting opinions on this issue, too. Some say the autopilot will do a better job of keeping the wings level and holding a level pitch attitude than any human can. Others, including yours truly, think that relying on the autopilot can cause big, big problems. In its effort to keep pitch or — in altitude hold — altitude under control, the electric trim motor will run almost nonstop. If the autopilot's force limits are exceeded, it will disengage, presenting the pilot with a severely out-of-trim condition, the need to frantically retrim, and the possibility of a stall or overspeed. Ditto with the forces the autopilot generates to keep the wings level or hold a heading. Better to work hard and hand-fly at a time like this, instead of letting George do it.

Turn up the cockpit lights. The idea here is to try to avoid being blinded by lightning flashes. The brighter the lights, the more rapidly the instruments will become visible after a bright flash. You also hear advice to close one eye, the theory being that you spare the vision in the closed eye, at the expense of the vision in the opened eye. This is especially good advice at night.

If you follow this advice, with any luck you'll ride out the storm and have a great story to tell. You'll also be a devout believer in the visual-avoidance school of thunderstorm evasion. Radar and lightning detection equipment can lie, but you can trust your eyeballs. Keep your distance and you'll never have to worry about ride-out measures.

E-mail the author at [email protected].

Tips for in-flight awareness of thunderstorms

• Monitor AWOS, ASOS, and ATIS frequencies as you fly. Listen for changing ceiling and visibility conditions and high (above 60 degrees Fahrenheit) dew points. Some stations may even have lightning reporting capability.
• Fly IFR, or use VFR advisories/flight following if available. Having a frequency already at hand lets you listen in on any weather-related diversions and ask for advice about routings around storm cells and buildups.
• Keep a VOR tuned to HIWAS (hazardous in-flight weather advisory service). Note the VORs that broadcast HIWAS and listen to the recordings for such weather advisories as convective sigmets and airmets.
• Depart early in the morning — like 5 or 6 a.m. By leaving well before the heat of the day you can maximize your chance of avoiding the worst of the buildups.
• Maintain visual separation from building cumulus and towering cumulus clouds, even if you are on an IFR flight plan. Keep at least 20 nm away.
• Don't fly beneath a thunderstorm.
• Don't try to outclimb a building cumulus or fly above a thunderstorm.
• Don't try to beat a thunderstorm to an airport.
• Periodically check in with flight watch (122.0 MHz) for weather updates.
• Use, and know how to use, lightning detection equipment and/or airborne weather radar.