An air pocket is generally temporary and does not indicate a deeper problem. The term is named as air pocket stock because as a plane hits an air pocket, the airplane faces a sudden drop in its’ altitude.
It is instance which happens on a very short-notice. However, in most cases, the prices of the stock gradually increase over a period of time, and reach to point similar to the earlier price.
If a government introduces a certain restriction on a certain product or service, there is a sudden decline in the stock market price due to this bad news.