Air New Zealand is being investigated over possible misleading or deceptive conduct in the way it sells insurance with air fares.
The Commerce Commission says the probe under the Fair Trading Act relates to "opt-out" insurance sold when customers book through the airline's website or mobile app.
Air New Zealand charges $10 per sector on domestic flights for insurance, unless passengers untick the option at stages through the booking.
The practice has led to at least one complaint to the commission. Air NZ also charges for selecting seats as customers book and, like other airlines, charges credit card fees.
A commission spokeswoman said insurance was the focus of the investigation and it was not looking at any other aspects of Air NZ pricing.