June 29 was the busiest day ever for Flightradar24.

Air travel just set a new record, according to a leading flight monitoring service.

Flightradar24‏, which tracks planes in real-time, estimates it monitored 202,157 flights on Friday - the busiest day the monitoring service has seen in its 12-year history.

The company put out a tweet to herald the landmark news, which comes as the airline industry launches an ambitious plan to reduce carbon emissions.

Flightradar24 describes itself as "the world's most popular flight tracking service, turning your phone, tablet, or computer into a virtual air traffic radar showing detailed aircraft and flight info for flights worldwide." It uses Coordinated Universal Time (UTC) for its data so is currently 12 hours behind New Zealand.

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The Sweden-based company could not provide figures for each country, but it did specify that historically, the greatest number of flights usually happened on a day in the last week of August.

The day with the least within the past year was on Christmas Day when only 101,511 flights were in the air (Christmas is usually the least busy day of the year).

For travellers wanting to avoid crowds, Flightradar24 said Thursday or Friday is the busiest day of the week.

The latest record corresponds with the influx of tourism in this country, international tourist numbers have risen 1.2m in the past five years.

Figures from Statistics NZ figures show 3.8 million tourists visited in the year to March - another record.

In the year to March, Australia remained our largest visitor market (39 per cent), followed by China (11 per cent), the US (9 per cent), and the United Kingdom (7 per cent).

Auckland Airport showed the biggest increase in arrivals, up almost 190,000, while Christchurch Airport arrivals rose 57,700 to 554,700.

Wellington Airport was the only main centre to show a drop, with arrivals down 3800.

However, the aviation records might not be a cause for celebration for some.

The aviation industry faces challenges to meet its own self-imposed climate change targets, according to a 2016 United Nations report.

The International Air Transport Association (IATA) adopted a set of ambitious targets to mitigate CO2 emissions from air transport, which included developing technology and reducing net emissions of 50 per cent by 2050, relative to 2005 levels.

The UN report indicated goals would not be easy will not be easy to reach.

Airlines estimate air travel will grow by an average of just under 5 per cent per year up to 2034 — and the emissions from these extra air miles will be difficult to decarbonise.

It is worth noting only 5 per cent of the world's population have ever travelled in a plane, according to transport campaigners Atmosfair.