timz From United States of America, joined Sep 1999, 6477 posts, RR: 8 Reply 4, posted (3 years 1 week 1 day 10 hours ago) and read 9266 times:
If you're looking at Mt Shasta from FL 380 over the Central Valley it should be visible from at least 300 miles. Roughly, distance to the horizon from Mt Shasta, plus distance to the horizon from FL 380.
Arniepie From Belgium, joined Aug 2005, 1265 posts, RR: 1 Reply 8, posted (3 years 1 week 12 hours ago) and read 8888 times:
AFAIK, the answers are incomplete, for instance you can see farther on the poles vs the equator due to the shape of the earth, also air temperature changes the light behaviour properties.
I remember reading somewhere that on a cold ,clear winterday some mountains on iceland can be seen almost from 400 miles away on cruising altitude. (IIRC)
cobra27 From Slovenia, joined May 2001, 995 posts, RR: 0 Reply 11, posted (3 years 6 days 13 hours ago) and read 8507 times:
Quoting TS-IOR (Reply 7): When you are FL380 the horizon is 239NM away, but people on ground won't see you when you are 239NM from their vertical. The maximum i have ever seen from ground is contrails from approx. 80NM.
timz From United States of America, joined Sep 1999, 6477 posts, RR: 8 Reply 12, posted (3 years 6 days 12 hours ago) and read 8472 times:
I've seen contrails 170+ miles away (747s making the turn over the Avenal VOR, seen from the hill above Berkeley, California). If I were standing on a higher mountain, with clear air and low sun backlighting the contrail against a fairly dark sky, 240 miles would be no problem with 10x binoculars.
AncientPelican From United States of America, joined Apr 2009, 34 posts, RR: 0 Reply 13, posted (2 years 12 months 3 days 16 hours ago) and read 7916 times:
I recall a TWA transcon heading westbound one evening where the pilot came on and said the people on the left side of the plane could see the lights of St Louis while those on the right could see Chicago.
rolypolyman From United States of America, joined Mar 2009, 152 posts, RR: 0 Reply 15, posted (2 years 12 months 22 hours ago) and read 7650 times:
I recall one night on AA in November 1996 we were at FL390 on a leg from the AEX to FZT VOR into DFW. I've been all over Texas and know the layout of cities like a map, and that's just what I was seeing with it being a particularly clear autumn night with city lights painting out the location of everything. Just before starting our descent I recognized our position as being just north of Nacogdoches. From that location I was able to easily distinguish the city lights of Waco, Temple, Austin, College Station, and Houston all at once. On the distant horizon I could distinctly see a nebulous but bright pancake smear of San Antonio, which was about 220 nm from where we were.
That was an amazing sight as I was seeing territory in one single glance that took many hours to traverse by car. It was almost like being in space. One of my best memories while flying, and definitely the furthest distance I can ever recall seeing from the air.
nomadd22 From United States of America, joined Feb 2008, 1577 posts, RR: 0 Reply 16, posted (2 years 12 months 16 hours ago) and read 7589 times:
Diffraction will only add about 40 miles to the distance of the horizon.
If you're flying around Tibet, all things considered, you should be able to see Everest peeking over the horizon at close to 500 miles.