Commercial or passenger aircraft are usually designed for optimum performance at their cruise speed or VC. Combustion engines have an optimum efficiency level for fuel consumption and power output. Generally, piston engines are most efficient between idle speed and 25% short of full throttle.
The blood to your head rushes when you do a quick movement, so, naturally, dizziness is expected. I think the blood rushes from your head too fast. it is called postural hypotension.. whereby, due to getting up suddenly to a upright position, there is lower blood supply to th head.
Follow the below given measures to put a stop to dizziness. 1  Improve your eating habits. Consume a balanced diet that is healthy and low in cholesterol. 2  Sometimes, reading while travelling may cause motion sickness followed by dizziness and hence, should be avoided if you experience such type of problem.