Royals Prince William Draws on 'First-Hand' Experiences in Personal Tribute to Air Ambulance Crews "The country owes you an enormous debt of gratitude," Prince William wrote in an open letter Monday to mark Air Ambulance Week 2020 By Phil Boucher Phil Boucher Phil Boucher is an editor at PEOPLE and based in London. People Editorial Guidelines Published on September 7, 2020 03:22 PM Share Tweet Pin Email Prince William. Photo: HEATHCLIFF O'MALLEY/AFP via Getty Images Prince William is drawing on his personal experiences to thank air ambulance crews for their vital, life-saving work. “Having seen first-hand the incredible work of air ambulance teams both on the front line and behind the scenes, I hold a profound respect for all that you do,” the duke wrote in an open letter Monday to mark the beginning of Air Ambulance Week 2020. “Whether you are part of the critical care team bringing vital medical support to patients when every second counts; an engineer who ensures that crews can be safely deployed at a moment’s notice; or a volunteer working to keep the service running, the country owes you an enormous debt of gratitude.” William, 38, worked as a pilot for the East Anglian Air Ambulance from March 2015 to July 2017, flying to numerous "daunting incidents," he revealed shortly before hanging up his flying suit. “One of the first call outs I made was to a young man who had committed suicide; it was an incredibly tough day and had a profound effect on all of us,” he added at the time. The cause has remained close to his heart. In March, the duke became patron of London's Air Ambulance Charity, while in May he gave permission for air ambulances to use the lawn of the Kensington Palace home he shares with wife Kate Middleton and their three children for refueling amid the coronavirus pandemic. Stefan Rousseau/Getty In the letter released Monday, William also took the opportunity to thank air ambulance workers for their vital work during the pandemic, which has tragically seen more than 300 members of the UK’s National Health Service and emergency responders lose their lives after contracting COVID-19 while on duty. Prince William Shares Every Parent's Fear on the Harmful Effects of Lockdown on Kids “The outbreak of COVID-19 has presented an immeasurably difficult challenge to all emergency responders,” William wrote. “You have had to adapt to new ways of working throughout the pandemic – while continuing to provide a crucial lifeline to those who need it most. "However, I know from experience that a wonderful spirit runs through the air ambulance community and I encourage everyone to continue to take time to support one another through these difficult times.” Prince William. IAN VOGLER/AFP via Getty Images This is the second time in four days that William has publicly praised the work of the U.K.'s emergency services. On Friday, the Duke paid tribute to the “sacrifices” emergency responders have made during the ongoing pandemic at a virtual festival of thanksgiving for first responders. "On behalf of my family, I want to thank you all for your hard work, your determination and your courage – you are a tremendous source of pride for our country and we’ll be forever grateful for all that you do," William said. "I am enormously grateful to all those who support the work of air ambulance services across the country — even through these most challenging of times," William added in the letter to all 21 of the U.K.'s air ambulance charities, which are funded solely by public donations. "This Air Ambulance Week, more than ever, I am delighted to see a spotlight shone on the work of this community and all those who support you," he continued. "Your tireless dedication to saving lives and helping those in times of greatest need is a source of huge pride for our country." Air ambulances also have a deep personal meaning to fellow royal Sophie, the Countess of Wessex, who was rushed to the hospital by Thames Valley Air Ambulance in 2001 after suffering an ectopic pregnancy. Last Wednesday (Sept. 03) Sophie, 55, made a poignant visit to the TVAA's HQ in White Waltham, Berkshire as they marked their 21st anniversary. Sophie, Countess of Wessex. Mark Cuthbert/UK Press via Getty Images Can't get enough of PEOPLE's Royals coverage? Sign up for our free Royals newsletter to get the latest updates on Kate Middleton, Meghan Markle and more! The royal mom of two was appointed royal patron of the service in January 2019 and in April joined one of TVAA’s weekly crew video calls to discover how paramedics and doctors were responding to the pandemic.