Heir travel! King Willem-Alexander co-pilots flight to St Martin as he joins wife Queen Maxima and daughter Princess Catharina-Amalia on the next leg of their Caribbean tour

Queen Maxima of the Netherlands and Princess Catharina-Amalia looked effortlessly chic in linen suits as they arrived at Princess Juliana International Airport during their Caribbean tour.

And it's no wonder they looked relaxed, given the co-pilot on their two-hour flight from Curaçao to St Martin was King Willem-Alexander himself.  

The 55-year-old monarch is a part-time pilot, and in 2017 it emerged that he'd been quietly flying for KLM for more than 20 years and frequently captained his own royal plane, formerly a Fokker 70, when going on state visits abroad.

The King earned his Airline Transport Pilot Licence in 2001, and in order to keep up his flying hours, he occasionally flies as a guest pilot for KLM Cityhopper. 

The Dutch King wore a navy blue two-piece suit paired with a bright orange patterned tie and white shirt while his stylish wife, 51, opted for a cropped wide leg, off-white suit, with a double breasted jacket. 

Queen Maxima of The Netherlands looked effortlessly chic in an off-white, wide leg linen suit as she arrived at Princess Juliana International Airport with her husband King Willem-Alexander

Queen Maxima of The Netherlands looked effortlessly chic in an off-white, wide leg linen suit as she arrived at Princess Juliana International Airport with her husband King Willem-Alexander

The elegant mother-of-three wore her blonde hair loosely curled with an off-cream floral headband. 

They were snapped arriving at the airport, before heading off to tour the Fire Station Cay Hill and SXM Medical Centre.

The Princess of Orange was neatly dressed for the busy day, in an ochre two piece linen suit with a cream textured shirt. 

Amalia, 19, like her mother wore her hair loosely curled and held onto a modern crotchet bag. 

King Willem-Alexander showed off his piloting skills as he co-piloted the royal's airplane on the eighth day of their Caribbean tour

King Willem-Alexander showed off his piloting skills as he co-piloted the royal's airplane on the eighth day of their Caribbean tour  

Princess Amalia looked stylish in an ochre linen suit as she joined her parents for a tour around the Caribbean island

Princess Amalia looked stylish in an ochre linen suit as she joined her parents for a tour around the Caribbean island 

The 19-year-old Princess of Orange accepted colourful flowers from locals and held onto a chic crotchet bag

The 19-year-old Princess of Orange accepted colourful flowers from locals and held onto a chic crotchet bag 

The royals have been touring the Dutch Caribbean Islands for the past week and on Monday's visit explored the island of Saint Martin. 

The popular family had a jam-packed day with lunch with the Government and a visit to Color Me SXM, a project on Sint Maarten by Be The Change Foundation. Plus a walking tour to see the reconstruction of the country after the event Hurricane Irma in September 2017.

However, it was King Willem that took the limelight, as he co-piloted the plane, which flew the family into Princess Juliana Airport. 

King Willem-Alexander has form when it comes to piloting planes; the monarch surprised passengers on a KLM flight in 2018 and today he was clearly keen to show off his skills once more.

King Willem-Alexander and Queen Maxima pictured on day eight of their visit to Dutch Caribbean islands. The royals were guided by locals to view reconstruction work of the country after Hurricane Irma

King Willem-Alexander and Queen Maxima pictured on day eight of their visit to Dutch Caribbean islands. The royals were guided by locals to view reconstruction work of the country after Hurricane Irma 

The royals are pictured here viewing the reconstruction work of the country after the devastation of Hurricane Irma in September 2017

The royals are pictured here viewing the reconstruction work of the country after the devastation of Hurricane Irma in September 2017

King Willem regularly practices his skills as a pilot for Dutch airlines KLM, after earning his Airline Transport Pilot Licence in 2001

King Willem regularly practices his skills as a pilot for Dutch airlines KLM, after earning his Airline Transport Pilot Licence in 2001

Queen Maxima is pictured here greeting locals as she arrived at Princess Juliana International Airport

Queen Maxima is pictured here greeting locals as she arrived at Princess Juliana International Airport 

The Dutch royals are pictured here arriving on the island. Queen Maxima kept her blonde hair loosely curled and wore a floral off-cream headband

The Dutch royals are pictured here arriving on the island. Queen Maxima kept her blonde hair loosely curled and wore a floral off-cream headband 

The royals have been extremely busy during their visit to the Caribbean islands and last week, while in Aruba, Queen Maxima and Princess Amalia were pictured cutting leaves from an aloe plant

During the Dutch royals' second day in Aruba, Amalia was seen cutting the plant while wearing thick yellow rubber gloves.

The Princess of Orange was neatly dressed in a voluminous green blouse and loose fitting white trousers.

More snaps were taken of Maxima and Amalia together, where they were pictured walking while holding a bouquet of flowers.

The popular family had a jam-packed day with lunch with the Government and a visit to Color Me SXM, a project on Sint Maarten by Be The Change Foundation

The popular family had a jam-packed day with lunch with the Government and a visit to Color Me SXM, a project on Sint Maarten by Be The Change Foundation

The family were snapped arriving at the airport, before heading off to tour the Fire Station Cay Hill and SXM Medical Centre

The family were snapped arriving at the airport, before heading off to tour the Fire Station Cay Hill and SXM Medical Centre

The Dutch royals explored the Sint Maarten site as part of their two week tour of the Caribbean islands.

The three have also penciled in visits to travelling to St Eustatius and Saba.

Until 2010, all the Caribbean islands, with the exception of Aruba, were part of the Dutch Antilles - an entity that was dissolved and its residents given the choice of independence or integration.

The arrangement is similar to that between the Commonwealth Realms, all of which have Britain's monarch as head of state but have separate directly elected parliaments.

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