Expression returns false even though it should return true

List<int> indexestoremove = new List<int>();
        List<FlightData> data = GetData();
        if(data == null)
        {
            return null;
        }
        for (int y = 0; y < data.Count; y++)
        {
            if (data[y].Planned < DateTime.Now)
            {
                if (data[y].Estimated == null || data[y].Estimated < DateTime.Now || data[y].Planned.Date > DateTime.Now)
                {
                    indexestoremove.Add(y);
                }
                
            }
        }

        foreach (var item in indexestoremove)
        {
            data.RemoveAt(item);
        }