New Zealand airlines is asking passengers to weigh in before their flights. In recent times, a circular advisory by the Federal Aviation Administration (FAA) sparked some discussion in the US about airlines collecting and knowing the weight of passengers for flights. This concern has been exacerbated by increased obesity rates in certain parts of the world. While the passenger weigh-in practice is not common for the standard check-in process, there are valid reasons why airlines may need to estimate or collect average passenger weights. This blog post aims to shed light on the significance of airlines knowing passenger weight for flights and how it influences various aspects of aviation operations.