On short haul flights this includes Jetstar (which charges between $8 and $15 for seat allocation), Air New Zealand ( between $5 and $10), and Qantas (which charges $16 for economy seat choices).
While these airlines deny intentionally breaking up passengers for profit, the implication is that air travellers will have to pay to sit together.
What was described in the CAA's investigation as a "nudge" to pay more.
Anecdotal evidence shows that booking groups which don't pay the "seating charge" are being split up, even when travelling with young children.
One Herald Travel reader got in touch to complain of being split up when travelling with a child on a Jetstar service to Phuket.
"I rang the airline and told them it was unacceptable to split a 10 year old from their parent and they were to seat at least one of us with her free of charge." This was rectified by the airline.
When contacted, a spokesperson for Jetstar said this incident was not intentional and not reflective of the airline's booking process.
"When passengers are travelling on the same Jetstar booking they are seated together where possible," they said.
Responding to claims that groups with shared surnames were being targeted, it was strongly denied. The airline said that many factors were taken into account when allocating seats, such as weight distribution and how late passengers booked onto a flight, but family names were not one of these.
However some passengers with children over 12 and old enough not to be classified as "unaccompanied minors" are still finding themselves allocated un-adjacent seats during check in.
It's a dilemma and an additional charge that solo travellers do not face.
With this stealth charge families feel they are being left with little option but to either pay up or be split up.
Airlines and policies
When asked to outline their booking practices carriers told Herald Travel they had the following advice to passengers:
Air New Zealand
The national carrier said that it tries to seat groups together, though "due to availability we may not be able to seat all travellers on the same booking in adjacent seats and in these cases, we will look to allocate seats nearby."
The airline encourages travellers to buy tickets on the same booking. Passengers with particular seating needs should consult its online guide.
For group bookings larger than 10 passengers Air New Zealand operates a group booking service: www.airnewzealand.co.nz/group-travel
Qantas
The Australian airline says the option is given for passengers "to select their preferred seats online during the booking process" and that during check-in, its airline staff "endeavour to seat families and travelling groups together as much as possible."
Qantas has a dedicated group booking service for parties travelling with 10 or more members: www.qantas.com/au/en/book-a-trip/flights/group-travel.html
Jetstar
"To assist passengers being seated together we advise they are all on the same booking," recommends the airline.
"Our team members at the check-in counter will do their best to assist with seating allocation based on availability and operational requirements on the day of travel."
However, Jetstar insists the "best option" is to pre-purchase their seat selection.