500 to 1000 feet AGL (Above Ground Level) is the minimum altitudes for aircraft, population dependant. In an area like this when the ground under the plane isn't flat, pilots have a hard time maintaining that exact min. altitude. There is also Class B airspace from 7,000 to 10,000 ft ASL (above sea level) for the bigger jets that are going into SLC International, so smaller aircraft have to stay below the 7,000 ft ASL. In this area that typically gives pilots about a 1,000 foot discretional altitude to stay within. The farther south you are of SLI airport, the more that changes, generally speaking. SO- the 500 to 1000 ft AGL would be about right for light aircraft. -Barrett www.FallenStarHunters.com www.BarrettsCustomLeather.com -----Original Message----- From: Utah-Astronomy [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of CenturyLink Customer Sent: Friday, July 25, 2014 12:49 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] UFO Hard to judge those things at night without a frame of reference. The "low altitude" is also difficult to judge. My home is on a lower bench so looking directly west from the back door, the view is already higher than the valley floor. Thinking back, I wasn't looking "up,", but almost "straight ahead." Based on that, a guess of an altiude between 500 and 1000 feet is reasonable.