1999-02-13 - Walnut Creek, CA - Unknown

Aircraft from SSW to E at extremely high altitude at extremely high speed, crossing visible horizon in 8 minutes, so high that shape was unsure despite 8x25 binoculars. Airliners commonly seen in Bay Area bear no resemblance in height, speed or perceived shape (trinagular). Seen 3-4 months earlier on same course, but then ascended so high it eventually left no contrails, and returned 15 min later, descending to level to create contrails. On 2/99 sighting, aircraft left two distinct, parallel contrails, despite fact aircraft itself could not be seen even with binoculars.