Flight standing-up in the sky and not moving

As usual, flight to Delhi is always fully book every week. Before we touch down Delhi international airport this week, the announcement mentioned that we are on the queue 16. It will take almost 30 minutes to be in the sky before we get clear response for landing. Well what happen, in the next day on the way for a meeting, I see a flight just standing-up in the sky and not moving, maybe waiting for the queue.

Does the aerodynamic technology have so high technology that allows flight to be in the queue in the sky and standing without moving like this picture?
This is the first time I see this.