In 1983, Pioneer 11 was predicted to be surpassed by Voyager 1 in the distace to the Sun and later by Voyager 2 around March 1988.
The probe was last heard on November 24, 1995 when the last communication between Earth and the probe ended due to power limitation and vast diatance, when it was 44.1 AU (4.1 billion miles or 7.5 billion km) from Earth.[1][2]
By Nov. 5, 2017, Pioneer 11 was estimated to be about 97.590 AU (9.1 billion miles or 14.599 billion kilometers) from Earth.
Both Pioneer 10 and Pioneer 11 had plaques etched in gold. The plaques were designed by a team lead by Carl Sagan to communicate with extraterrestrial life should the spacecraft come into contact with it.
By 2027, Pioneer 11 is predicted to have exited the heliosphere and entered interstellar space.
Pioneer Odyssey, NASA SP-396, 1977Archived 2006-08-13 at the Wayback Machine - This is an entire book about the Pioneer 10 and 11 project, with all pictures and diagrams, on-line! Scroll down to click on the "Table of Contents" link.