Low altitude passenger-type jet emitting thick contrails blinks out of sight in a cloudless, baby blue sky!It was 18:15 on Super Bowl Sunday. I went outside to the backyard to check the turkey roasting on the barbeque. The day was a beautiful clear day in Phoenix, Arizona. The sky was baby blue and cloudless. As I was tending to the turkey, I heard a very loud jet roar. The sound was louder than normal so I looked up. The first thing I noticed was a very thick double contrail not very high up in the sky. My eyes followed it to the object making it. It was a white passenger type jet. From where I stood, the craft was five inches long, and it was near enough to make out what airline it was, but there wern't any markings at all. The thick contrails were emitting from each wing. The aircraft was heading from SW to NW. As I watched the contrails continued unbroken then suddenly each contrail had a short break in it, and then each contrail continued for a very short length and then the entire passenger-type jet Blinked Out! It just vanished into a clear baby blue sky before my eyes! It was nowhere to be seen. I went inside to record the event in my journal.((NUFORC Note: We have not received any other reports about the incident, but would like to have anyone who may have been witness to this incident to submit a report. A typical airliner, that appears to a witness on the ground to be "five inches long," would, indeed, be at a very low altitude. Typically, jet aircraft at low altitude do not generate contrails. PD))