Recently I flew from Chennai to Delhi through Vistara airlines. I had bought with me a power bank and had dropped it into the check-in baggage. While I was waiting in the lounge I was called upon to the baggage security area and was questioned regarding the same and had to open the check-in baggage and throw out the powerbank as it was not allowed to be carried in their airlines. In the same way couple of weeks back when flying through Indigo airlines I was allowed to take the powerbank in cabin baggage when I flew from Bangalore to Chennai. So there is no uniform guideline for airlines regarding what is prohibited and what is not?