Although there is no official announcement on Air Niugini's website, chairman Kostas Constantinou published a letter on The Sunday Bulletin's Facebook page.
Constantinou wrote: "We would like to thank Alan Milne for all his efforts over the last 18 months in his role of CEO.
"Covid-19 has had a detrimental impact on the airline industry and our CEO's capacity to travel back and forth to his family in Australia.
"Air Niugini takes the health and safety of its employees seriously and as seriously the biosecurity laws of the countries in which we operate.
"Alan Milne will be leaving Air Niugini as of today to be with his family. Alan is disappointed and regretful that this is the outcome, however his family must come first in these extremely worrying times.
"Bruce Alabaster, the general manager of Link PNG, is appointed acting CEO.
"Bruce is a recognised leader of the industry, originally from New Zealand and started working in PNG 24 years ago, initially as a pilot flying across all of PNG.
"Bruce has a Masters in Aviation and has been married to a Papua New Guinean for 20 years," Constantinou concluded.