[B-Matt]

pawn Код:

OnPlayerUpdate(playerid)
{
    new Float:Velocity[3];
    GetVehicleVelocity(GetPlayerVehicleID(playerid), Velocity[0], Velocity[1], Velocity[2]);
    if ( Velocity[2] < building height)
    {
         //your code
    }
    return 1;
}

Try this code..