Earth's magnetic field and planes.

First we convert the quantities into their standard units. So, $v=900km/h=(900*1000)/(60*60)m/s=250m/s$ Also it is good to note that $B=50*10^{-6} T$ By Faraday's Law the induced voltage will be equal to the product of the magnetic field, length of the conducting rod and the speed at which the rod is traveling. So induced $V=BLv=(50*10^{-6})(60)(250)=0.75 V$

Let us focus on a electron in the wing, which is free to move since the wing is a conductor. The magnetic force acting on this electron has a component directed along the wing given by $F_{m}= e v B .$ since the velocity and magnetic field are perpendicular. If everything has come to equilibrium and the electrons are stationary there must exist an electric field along the wing canceling this magnetic force. Thus $e E= e v B \rightarrow E= v B \rightarrow V=vB L=0.75 V$

The origin of this electric field is easy to understand. Suppose that initially a conducting rod is at rest in a magnetic field. If the rod starts moving, then the magnetic force will cause some electrons to accumulate at the tip of the rod. This situation is similar to that of a capacitor. This redistribution of charges is the reason why an electric field is created. The electrons will drift towards the end of the rod until the electric force cancels the magnetic force.