Flying through Thunderstorms

Oct 15
07:53

2008

Douglas W. Daniel

Douglas W. Daniel

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Practical advice for the pilot who accidentally gets caught in an embedded thunderstorm. While this should never happen it does. Keeping your head is essential to survival and having a course of action to follow is essential to keeping your head. That course of action is spelled out here. Written is simple, conversational style.

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A very senior pilot was asked,Flying through Thunderstorms Articles "How might I fly through a thunderstorm that I could not avoid?"

The answer he wanted to give was either, "You can't." or "Don't try."

But the question needed to be answered. Here is his advice:

Just about the only way to inadvertently get into a thunderstorm is by flying instruments in clouds with embedded thunderstorms and without either weather radar equipment onboard or ground-based weather radar available to your air traffic controller. Let's assume this is how Fate dealt you such a poor hand.

The biggest danger in a thunderstorm is structural failure. My advice is: don't do anything that helps the thunderstorm break your airplane. When you realize that you are in trouble, slow down. I mean not just to maneuvering speed but much slower than that. Slow to what is known as 'slow cruise' - the speed that you use in holding patterns. This will be fairly close to the best rate of climb airspeed for your airplane. Slow cruise is slow enough to minimize the adverse effects of turbulence and fast enough to keep your controls responsive. Consider putting your wheels down. This will help you stay slow. Most airplanes are not as strong with flaps out, so don't use flaps unless there is no restriction against it in your pilot's handbook for the airplane.

The reason to slow down is that the higher your airspeed, the greater force turbulence can impart on your airplane. That destructive force comes in the form of lift. Remember that the lift of a fast wing is much greater than the lift of a slow wing. Slow is good.

Too slow is not good simply because the last thing that you need is to stall and spin when you are in a thunderstorm.

There is an expression in aviation that says a pilot's priorities are aviate, navigate and communicate, in that order. I agree. Certainly your most important task is to fly the airplane. However, you need all the help you can get. So tell air traffic control (ATC) that you are in trouble and need help. Ask them to vector you out of the thunderstorm. Tell them that you cannot maintain the assigned altitude - because you cannot. Ask them to vector you away from high terrain. Be aware that your inability to maintain altitude can easily put you in a position where you cannot hear ATC for some time.

The intensity of rain in a thunderstorm can be truly phenomenal. Quite possibly your engine or engines can start to ingest a great deal of water. This water can turn to ice in your carburetor especially at high altitudes and low power settings. When you apply carburetor heat, the mixture enriches forcing you to lean the engine or risk fouling the spark plugs. Tuning the engine is an integral part of flying the airplane, your most important task.

The updrafts and downdrafts in a thunderstorm can be far greater than a general aviation airplane's ability to climb or dive. So just ride them out. Don't start building airspeed by pushing your nose down to stay at your assigned altitude in a strong updraft. If you get caught in a strong downdraft, go to your best rate of climb airspeed at full power. You will still go down - just not as fast and not so far. When the downdraft dissipates, you can start climbing back to your assigned altitude. If you have oxygen and perhaps if you don't, ask ATC for a higher altitude so you will have a greater margin of safety when you enter your next overpowering downdraft. If ATC will not grant you a higher altitude, do not be afraid to declare an emergency and tell ATC that you are going to a higher altitude.

There are two things that you should remember here. First, if the FAA issues a violation, it is better to argue in court that you needed that higher altitude than it is to have the surviving members of your family argue in court that the FAA should have cleared you to a higher altitude. Second, when you go high without oxygen, you get so stupid that you don't know how stupid you are. Having said that, when you are at 10,000 feet facing 12,000 feet peaks and a known thunderstorm behind you, the options start to narrow. For me, it is better to face hypoxia than certain death.

To sum it up: Plan your fight and check your weather well enough to know that you are not going into a thunderstorm.

If, by some fluke of nature, you end up in a thunderstorm that was not predicted and you could not see, then

1.) Slow down.

2.) Remember that flying the airplane is your most important task.

3.) Get out of the thunderstorm as quickly as possible.

4.) Keep going straight with wings level while you ride out overpowering up and downdrafts.

5.) Tell ATC.

6.) Ask for help.