KATE and Wills took their family on a budget £73-a-head FlyBe plane to Balmoral - days after Harry and Meghan took four gas-guzzling private jet trips in 11 days.
Celebrity friends of "eco warrior" Meghan have been forced to defend the former actress - claiming she couldn't get commercial flights due to the "security risk".
But down-to-earth Kate and William travelled with the budget airline from Norwich International Airport to Aberdeen Airport this morning at around 8.50am.
The total cost for the family of five would have been just £365, while Harry and Meghan's private Cessna jet - paid for by Sir Elton John - costs around £20,000 to hire.
Footage shows Prince William struggling across the runway while holding four bags with his son George, six, and daughter Charlotte, four, in tow.
The young royals were also filmed carrying their own backpacks as they made their way to black Range Rovers waiting to whisk them to Balmoral to see the Queen and Prince Philip.
At one point, Prince George made a grab for his dad's already full hand as his sister happily skipped behind.
Stunned passengers also watched as Kate followed carrying one-year-old Louis, who appeared to be looking around the runway.
She was flanked by nanny Maria Borrallo, who also travelled on the 40-seat passenger plane with the family.
One passenger said: "Earlier in the flight, I'd had the feeling that someone had come on the plane that I'd recognised - but I thought it was just a footballer.
"We landed, and people then saw two black Range Rovers on the tarmac.
"Suddenly, Will, Kate, and the kids all got up, and left.
"They weren't harassed by anyone at all as they got off the plane. They just seemed like a family travelling together to be honest.
"No one saw them get on the plane either. It was amazing how they did it - they must have slipped on quietly, after people were already seated."
The traveller said they had security on the plane and passengers were blocked from using the loo as it was apparently "out of order".
They added: "I couldn't believe my eyes. You don't expect to see royalty on a budget airliner."
PRINCE HARRY AND MEGHAN MARKLE'S JET-SETTING CARBON FOOTPRINT
The Duke and Duchess of Sussex travelled by private jet on their holidays this summer, which generates an estimated seven times more emissions per person than commercial flights.
Their return Nice flight is estimated to have a carbon footprint of over three tons.
This is in addition to their Ibiza trip earlier this month which is thought to have a footprint of over four tons.
A tree removes around seven tons of carbon dioxide from the air once fully grown - and this equates to the royal couple needing to plant one tree to offset their carbon footprint of their two trips this month.
The average UK person has a carbon footprint of 13 tons a year.
The couple are making their way to Balmoral, where they usually spend the bank holiday weekend with the Queen and Prince Philip - but Meghan and Harry won't be joining them.
A royal source said: "The Queen loves spending time with all her great-grandchildren and they all call her Gan-Gan.
"Harry and Meghan won't be going up at the same time as William and the cousins.
"They plan to go next month."
It comes after Meghan, 38, and husband Harry, 34, were accused of hypocrisy after recently speaking out about environmental issues, then using private jets for trips around Europe.
Photos emerged of the Sussexes boarding a private jet with son Archie - despite frequently preaching about the environment.
They took four private jet flights in just 11 days, and the flights would have generated an estimated seven times more emissions per person than if they had flown commercially.
There are more than 20 scheduled departures from London airports to Nice each Wednesday, with an EasyJet return costing £232.
Sir Elton John defended the couple for taking the £20,000 jet to France, saying he booked it due to the couple's "high level of much-needed protection."
GREENPEACE CHIEF SCIENTIST SAYS ELTON JOHN'S CARBON OFF-SETTING SCHEME WILL HAVE NO 'MEANINGFUL EFFECT' ON CLIMATE CHANGE
Elton John said that he had made a donation to Carbon Footprint to offset the carbon costs of the jet he booked for Prince Harry and Meghan Markle.
But Greenpeace’s chief scientist Doug Parr said that it’s “not okay” to assume the trip was therefore “carbon neutral”.
It is estimated the couple’s return flights from England to Nice generated around seven tonnes of CO2.
Many of the schemes run by UK registered company Carbon Footprint focus on putting in place systems which stop CO2 being released into the atmosphere.
One scheme, for example, helps to provide efficient stoves to Kenya villagers, who currently burn wood and charcoal to cook.
Dr Parr said to the : “They're not wrong things to be done, but they're not the answer that's meaningful in terms of the climate challenge we face.
“The two aren't equivalent. If you've got big puffs of CO2 which come out almost instantaneously, yes over years and years it gets slowly absorbed but over those years it's been warming the planet.”
According to Carbon Positive Life a single tree can absorb 48lbs of CO2 per year – so it would take 321 years to absorb seven tonnes.
Other A-listers have rallied round Meghan after she came under fire.
Ellen DeGeneres, 61, chimed in the debate saying the Duke and Duchess of Sussex are attacked “for everything they do”.
British actress Jameela Jamil made a wild claim that England hates Meghan “because she’s black” - prompting a furious response from Piers Morgan.
And pal Jessica Mulroney slammed "racist bullies" on Instagram as the row against the royal couple intensified.
She wrote: "When someone faces unfair criticism, you call it out.
“When that person is your friend and your family, you call these critics what they truly are.
“Shame on you, you racist bullies.”
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The jet-setting holidays came just after Harry attended a super-secret Google Camp event in Sicily - on July 30.
While there, the barefoot Prince gave an impassioned speech about climate change to celebs believed to include Leonardo DiCaprio, Naomi Campbell, Stella McCartney and Harry Styles.
He also repeated his vow to only have two kids because of his eco-concerns.