A decision by Qantas not to allow a toddler to travel in the care of her teenaged brother shows how easily New Zealanders can be hurt by poorly set-out documents, says a trust promoting the use of plain English.

Anna Grace bought tickets on a recent flight from Christchurch to Queenstown for her son Hamish, 14, and Montana-Rose, 2.

However, Qantas airline officials stopped Montana-Rose from flying because Hamish was not 15-years-old.

Grace said she had assumed Hamish could act as a caregiver for her daughter as he had to travel on an adult fare.

A Qantas spokesman said the company's rules were simple.

"A 14-year-old is an unaccompanied minor and they can't accompany another unaccompanied minor.

"It's all listed on the website."

But WriteMark Plain English Awards Trust chairman Christopher Travers said on Thursday the Qantas online bookings site did not set out information about conditions for unaccompanied children in a clear, logical sequence.

"While Qantas may have good reasons for these rules, explaining them unclearly has left Mrs Grace in a very inconvenient situation, and that isn't fair," he said.

"She assumed that her daughter was not travelling alone because she was in the care of an older brother paying an adult fare. This assumption seems reasonable according to the Qantas website booking process."

Travers said there were lots of documents and websites in New Zealand that could cause similar or even worse harm.

Several have already been nominated for People's Choice "Brainstrain" awards in this year's WriteMark New Zealand Plain English Awards.

The awards, to be announced in Wellington on September 11, are promoted by the WriteMark Plain English Awards Trust to publicly honour organisations that communicate clearly.

Many entries have already been received, with more expected before the July 28 deadline.

"Most entries have been for documents or websites people like because they are easy to understand," Travers said.

"However, confusing or badly structured information remains common. The judges always have plenty to choose from in the 'Brainstrain' categories."

The award details can be found on www.plainenglishawards.org.nz.