Hi Barry,
I have IPF since 2015 and up to March last I was not on supplemental oxygen. I had been misdiagnosed as suffering from post infection asthma until September 2016. After confirmation by biopsy my first pulmonary consultant had no issues with flying and I had no difficulties either though typically my flights would be of one to three hours duration. In April 2018 when I was hospitalised I was found to have three fractured ribs as a result of persistent coughing, it was determined that my IPF was not responding to the high tech drug that I had been put on in April 2018 and I was transferred to a second consultant with a view to having a lung transplant. After a full hospital workup I was put on the active transplant list in May. However this consultant completely rules out any flying mainly on the risk of airborne infection in the recycled air of an aircraft. He also put me on 24/7 supplemental oxygen. I have not flown since but I found that our national airline does not allow oxygen concentrators on their aircraft but can supply an oxygen connection for approximately 200 dollars! Apologies for such a long winded comment but I really just wanted to say that flying gave me absolutely no discomfort. Back then my oxygen saturation levels were typically 92 to 94 with no supplemental oxygen.