ORIGINAL: krementz
Many relays consume power continuously if on. For example, a normally closed relay when off consumes nothing. Turning it on, often there is a small solenoid holding the contacts open, consuming some power. In the situation of a one hour flight, it probably doesn't matter. If it is on for two weeks, the power consumption might be significant.
A stepping sw does not consume power after it moves. A stepping sw is a type of solonoid relay.