A consumer advocate is warning of a carry-on baggage crackdown as the battle between airlines for budget-conscious customers sees a growing number of seat-only ticket sales.

Air New Zealand, which has recently gone head-to-head with Jetstar on budget domestic flight deals, has started warning passengers at the airport that its 7kg carry-on limit is being strictly enforced.

"The introduction of our popular 'seats to suit' fares on domestic routes has naturally seen more passengers travelling on seat tickets with carry-on baggage only," an Air New Zealand spokeswoman said yesterday.

A Jetstar spokesman said the airline kept "a close eye on the size and weight of baggage taken on board, both for safety reasons and for the comfort of all passengers".


Consumer New Zealand chief executive Sue Chetwin said passengers who pushed the limits on the weight and size of their carry-on luggage could expect to be stung as airlines sold more seat-only flights.

"You do know when you book your fares what you can and can't take. If you choose to rely on their goodwill [to allow extra carry-on] ... then I guess you're in for a surprise," Ms Chetwin said.

"If these fares are incredibly discounted, I guess [the airlines] are tightening up."

Air New Zealand recently slashed ticket prices to $7 each way between Auckland and Wellington for late-night flights in the lead-up to Christmas.

The deal beat Jetstar's $19 flights each way between the two destinations. Both prices were for carry-on baggage only.

"When you're in the airport [the airlines] seem to be making announcements more regularly about how much carry-on luggage you can take and the importance of having one piece," Ms Chetwin said.

"They are trying to be competitive and one of the ways of doing that is offering those fares where you only have your carry-on baggage."

University student Grace Kane, 19, said she had noticed Air New Zealand was giving extra attention to its carry-on limits when she flew home to Palmerston North this week.

The forensics student said she had to throw out a few kilograms of beauty products because her bag had been too heavy when she moved home last summer.

"[Previously] I've only been asked to weigh my carry-on bags when they've been too heavy for me to carry and I've been kicking them along the ground," Ms Kane said.

"People are pushing it more because there are cheaper flights with only carry-on, so it doesn't surprise me that they're being stricter."

Internet marketer Reno Van Boven said he faced $105 in extra baggage charges on an Air New Zealand flight between Wellington and Nelson at the weekend when he was asked to check in his 9kg bag and 2.5kg guitar, both of which he said he had always been allowed to take on board in the past.

Mr Van Boven said he managed to take both items as carry-on baggage but was warned he faced paying full price in the future.

Ms Chetwin said it should not shock customers that airlines would be stricter about carry-on luggage for discounted fares.

"To their credit they make it really clear what you can and can't take."