His death was announced by his family in the Westmorland Gazette on 29 October 2020:
MILLIGAN Frank It is with great sadness that his family announce that Frank died on 19th October at Furness General Hospital after a short illness. He was a dearly loved husband, father and grandfather who will be greatly missed. Private funeral. Enquiries to Fishwicks, Beetham, 015395 63108. No flowers, however donations can be made to the RAF Benevolent Fund www.rafbf.org
Tony Mooney emailed on 5 March 2021:
I'm sorry to tell you that Frank Milligan has died. I spoke to his daughter yesterday after Tony Beard mentioned there was an item in the latest RAFLAA Newsletter saying he had died. His daughter said that he died in hospital on 19th October 2020 having been quite ill with a number of problems over the last few years. She didn't want to tell me the details as Frank wouldn't have wanted it. He was admitted to hospital that day in very poor health and very sadly died later that day.
Derek Orgill wrote in an email the same day:
I am so saddened to hear that Frank has passed away. I spoke to him last summer and he sounded in good spirits. Frank achieved so much in his Flying Career. Other members of our entry may have attained a higher rank but no one could match his achievements. I'm sure Hilde will get all the support she needs from her children. RIP Frank.
Ray Thorne said in an email on 5 March 2021:
Very sorry to hear another of our entry has faded away. I believe Frank piloted one of the Victors to Port Stanley in ‘ 82. RIP Frank.
Copper Kyte wrote on 5 March 2021:
So sorry. Frank was a fine gentleman with numerous achievements that one could only admire. Our condolences to Hilde and family. RIP.
From Keith Runacres by email on 6 March 2021:
I didn't know anything about Frank's career but sorry to hear the news. RIP Frank and deepest condolences to Hilde.
From Bryan Drake in Cyprus on 7 March 2021:
So sad to hear another of our friends has died. It brings home the memories of the special comradery of our youth at Locking which stays so strongly with us throughout our lives. Frank stood out as a respected leader in our entry. RIP Frank.
Derek Orgill said in another email on 10 March 2021:
Thanks for informing us about Frank passing away. It was a shock and very sad. Another of our "brothers" gone.