So, you have one sole instance to offer as a counter and it happens to be in a place you would have been able to visually detect a referenced landmark perhaps matching the flight map.
How in the world would this translate to a transoceanic flight having little if any similarity to the flight you cite?
If you need many more descriptions of long-haul airline flight experiences, I have plenty for you.
While I was working, I took lots of long-haul transoceanic flights. Some were up to 15 hours long. On those flights I sat in business class or first-class seats. There was always a map with the aircraft’s position and ground speed displayed on the screen in front of me. Sometimes there was even a forward-facing camera allowing me to have the same outside view as the aircraft’s captain on my display. If I wanted to double check I could pull out my GPS receiver and have a 2
nd source of speed & position data. This worked OK especially when I was in a window seat. I am an experienced commercial pilot/ship’s officer/ and navigator myself and was never surprised when I could confirm the aircraft’s position with landmarks below. We would always start flying a great circle route to save fuel and sometime would go way up into the Artic on flights from the USA to Asia. Sometimes that route would be altered to avoid unfavorable weather conditions. You can be sure that high altitude jet streams were taken into account when the pre-flight planning was done. There were times when we did divert for a refueling stop before reaching our destination but that didn’t happen very often. When it did happen, there was always bad weather along the way and the pilot would make some diversions to avoid thunderstorms, typhoons, or hurricanes. We did once land in Beijing, China to refuel on the way to Hong Kong but there were frequent storms along the way, plenty of adverse head winds and the weather was foggy in Hong Kong. It made sense to be safe and have plenty of reserve fuel in case a diversion or a holding pattern was necessary near the end of the flight due to the unpredictable visibility at our final stop.
The bottom line is that I have the experience of many hundreds of trans-oceanic voyages by air and sea during my working years. You always knew your position and speed over the ground very accurately. If someone tells you the contrary, they might very well not be able to determine their position correctly, but experienced navigators certainly can, very accurately, determine both their position and speed over the ground. If they can't then there is a serious problem with their equipment. I don't believe that I ever had that happen to me in over 40 years of traveling. I always had a backup or two to fall back on if a single piece of equipment failed. Sure, in my early years, I had some navigational difficulties, but that was due to inexperience. I got better & better at using the navigational equipment and reading navigational charts as my training & experience progressed.