Fire and Emergency NZ told crews on Friday the CAA had raised concerns over loose items, such as flags or banners. But the firefighters had to be told again after they arrived at Christchurch Airport for an emergency callout on Sunday.
Industrial action by the paid firefighters' union - the NZPFU - started after FENZ made a pay offer of 5.1 % over three years in June.
Flight NZ5804 from Christchurch to Tauranga was on the taxiway when the ATR-72 reported an aircraft system indication alert that an engine was on fire.
About 70 people were on board the flight, but no fire was found.
FENZ said CAA warned it about the risk of flags and banners blowing off and becoming a hazard on the tarmac.
"We communicated to our frontline leadership on Friday that fire trucks should remove flags and banners to assist safety," said a FENZ spokesperson.
"There was no delay to the response to Christchurch Airport, because the trucks had to wait at one of the airport gates in any case before proceeding onto the operational area, so any items that hadn't already been removed would have been taken off there."
FENZ said crews were reminded to remove flags from their trucks for safety reasons before entering the airport.
The New Zealand Professional Firefighters Union (NZPFU) said it was happy to comply with the directive as safety was important.
The union said management issued instructions that firefighters should wear FENZ t-shirts when carrying out fire safety duties, such as installing smoke alarms or school visits.
Volunteer firefighters say the t-shirts, emblazoned with 'Dire Emergency', have been worn by paid firefighters turning up to other jobs, such as heart attack call-outs.
The union said it had not been made aware of any problems with the shirts.
"We respect the New Zealand Professional Firefighters Union's right to take industrial action," FENZ said. "We expect union members to act or present themselves appropriately at incidents."
