The Queen quipped with an airman about whether Typhoon jets have been "sent to chase the Russians" on her first outing in five months.
Her Majesty, who it is reported had her second Covid vaccine dose shortly before this first engagement of 2021, was marking the centenary of the Royal Australian Air Force (RAAF).
She paid tribute to the "skill and sacrifice" of the RAAF during her first public engagement of the year outside Windsor Castle.
During a service at the Commonwealth War Graves Commission (CWGC) Air Forces Memorial in Runnymede, Surrey, the Queen commemorated the 100th anniversary of the RAAF.
In a lighter moment, the Queen quizzed Squadron Leader Matthew Sander about his job as a fighter controller working with Typhoon jets and asked if they had been "sent off to chase the Russians" and was told "That's correct, ma'am, it's a lot of fun for us!"
Sending her "best wishes and congratulations" to the RAAF, she wrote in a foreword to the order of service: "As one of the oldest air forces in the world, it is fitting to pay tribute to the efficiency, skill and sacrifice of the men and women who have served in its ranks, in Australia and overseas, during the past 100 years.
"Throughout my reign, the Royal Australian Air Force has shown immense dedication to duty and has defended our freedom in many conflicts around the world."
As she arrived at the memorial, which she opened in 1953, the Queen highlighted how long it was since she had last been there.
She added: "You've got a good day for it. It's a very windy spot normally."
The ceremony began with a flypast by the Red Arrows, but with white smoke only instead of the familiar red, white and blue. As they do not normally perform at this time of year, their smoke pods are being serviced.
During the service, a wreath was laid on behalf of the Queen by her new equerry, Major Thomas White.
More than 350,000 men and women have served in the RAAF since its formation in 1921, fighting in conflicts ranging from the Second World War to Korea, Vietnam, Afghanistan and Iraq, with more than 11,100 losing their lives in service.
The event at Runnymede is the fourth royal engagement the Queen has attended beyond the walls of Windsor Castle since the pandemic began.
She has spent much of the pandemic shielding there in a bubble with husband Prince Philip, who recently spent nearly a month in hospital.
She was last seen outside her Berkshire residence in November during the annual Remembrance Sunday service at the Cenotaph and, a few days before that, wore a face mask in public for the first time during a poignant visit to the grave of the Unknown Warrior at Westminster Abbey to mark the centenary of his burial.
A few weeks earlier she was joined by her grandson, the Duke of Cambridge, when she visited the Defence Science and Technology Laboratory, Porton Down, in Wiltshire and formally opened the Energetics Analysis Centre.
The Queen has been carrying out her duties as head of state throughout the pandemic and has taken part in a number of memorable virtual royal engagements via video call, including one where she encouraged those who were hesitant to have the vaccine to "think about other people rather than themselves".
A number of high-profile events have been staged in the grounds of Windsor Castle including a ceremony last summer where the Queen knighted veteran NHS fundraiser, Captain Sir Tom Moore.
Australia's High Commissioner, George Brandis, said in a speech that the RAAF was the second oldest independent air force in the world: "The Royal Australian Air Force has, over these 100 eventful years, grown to be one of the most accomplished in the world."
After the service, the Queen was shown the names of some of the 1,383 Australian war dead who are commemorated on a panel.
The Queen was wearing a lime green and ivory dress and jacket by Angela Kelly with matching hat, and the Australian wattle brooch presented to her during her 1954 tour of Australia.
Before she left, she spoke to Mr Brandis about the number of Australians stuck in Britain because of the pandemic. After he told her of the efforts being made to get them home, she said: "There are worse places to be stuck."
He also spoke to the Queen about the fact that it was her first public engagement of the year and she replied: "I'm delighted to be here."
The Queen was given the promise of a present, to be delivered later when they have been made - two RAAF dog jackets for her new corgi and dorgi dogs.
"That's very kind," she said. "I look forward to it."
