The Rainbow Division, on the morning of October 10, 1918, was lying in what had at one time been a wood just back of Montfaucon. The sky was clear except for a few fleecy clouds to the northwest. Three airmen came from the northwest and passed almost over our regiment, continuing on to the southeast. Behind each machine was a trail of white, which at first sight appeared to be smoke resulting from poor engine combustion, but which upon more careful observation proved too wide to have been caused by smoke. Perhaps the strangest thing of all was the fact that when the planes reached a certain point in the sky the rainbow (sundog) colors became distinctly visible.
Originally posted by Phage
The contrails could have been made by an electronic reconnaissance aircraft such as an E-3:
or an aerial tanker:
or some other military aircraft flying a mission which would require them to stay in a specific location for a period of time.
[edit on 3/2/2009 by Phage]
Originally posted by JoeBarna
Without more details, or having been able to monitor the controlling agency's frequency, the reason for the circle is anyone's guess. It could have been a timing turn to make an arrival time further down the road, it could have been (as you guessed) an aircraft dumping gas in order to lighten his weight for an emergency landing, or it could have been directed by air traffic control to guarantee proper spacing between aircraft along the same flight path.