public async override Task Update <T>(T item)
{
if (typeof(T) == typeof(Aircraft))
{
InternalData.UpdateAircraft(item as Aircraft);
}
if (typeof(T) == typeof(Airfield))
{
InternalData.UpdateAirfield(item as Airfield);
}
if (typeof(T) == typeof(AcType))
{
InternalData.UpdateAcType(item as AcType);
}
if (typeof(T) == typeof(Flight))
{
InternalData.UpdateFlight(item as Flight);
}
}