A number of years ago it was discovered that airplanes could suddenly loose a lot of altitude when entering big, mysterious 'air pockets'. It was thought that this was the explanation for a number of mysterious airplane crashes like Eastern Airlines flight 66.

In the beginning no one could believe this phenomenon existed. It was simply not possible that there could be ‘pockets’ in the air or downward airstreams. What was involved was not an ordinary turbulence, but severe pockets in the air, causing sudden plane crashes. The phenomenon has been noticed especially in cases where both the speed and the altitude of an airplane have been low.
 
We already know that winds inside and around thunderclouds can be unpredictable. Flying into such clouds is not recommended. 

It seems like thunder clouds (small low pressure systems) work in the same way larger low pressures systems do. Around small thunder storms low pressure air likely also circulates about the centre and rises as it does so. This will lead to a calm region in the centre of the storm.

If so, an aircraft flying into such a low pressure system will first be supported by upwards moving winds, and shortly after, when it enters the centre, the plane will suddenly lose this support and instead be affected by a force in the opposite direction. This means the aircraft may rapidly lose altitude if flying at low speeds into a low pressure system of an appreciable size. One could imagine that such an affect could cause an aircraft to suddenly crash.

This could support the idea that the cause of weak low pressure systems, like those which breed tornados, is not well understood, as mentioned in the previous chapter on the tornados. It also shows that something could have been overlooked when it comes to our understanding of low pressure systems on larger scales.