Originally posted by onesockon
reply to post by weedwhacker
youve been a pilot right? if they are belting out that thick then why dont i see them when i sit in a window seat behind the wings
Good question, onesockon, thanks for asking.
If you closely examine photos taken from the ground, or even taken from other airplanes as we pass each other, you will see a distinct gap in the
'trail'...it forms very consistently a few dozen feet BEHIND the airplane. You will not see the contrail the airplane you are sitting in. You may,
if you manage to spot one, another airplane above or below you, possibly converging or diverging with the course you happen to be on.
Heck, I'll have to repeat myself...Sometimes, over the North Atlantic, we can see the contrails of the airplanes above, on the same track, or
below....but NOT always, because when the air is too dry, contrails don't form. Sometimes the trails last a long time, sometimes they dissipate
within minutes.
When you do some studying of meterology, things that we say will make more sense, perhaps.
Thanks for your post.
Add for clarity: I mention the NAT tracks (North Atlantic) tracks because we stay on a determined course, based on Lat/Long coordinates, and don't
get to go 'direct' as is often done in a radar environment, as in, the Continental United States.
The NAT tracks are created every day, and will vary by Latitude to maximize or minimize the prevailing winds, depending on your direction. The
majority of traffic Eastbound is in the evening, and overnight, so won't see many contrails there! In the mornings, most NATs are Westbound, Europe
to North America.
These tracks 'anchor' at a particular designated intersection, or VOR...and they are designated by Lat/Long points, as in, for example...track 'C'
might leave from Gander...and then fly to 50N/50W. Next point could be 60N/40W. Next, 61N/30W (where we switch over to a different Oceanic Control
ATC authority). Usually, 'cause it's a great circle, we will reduce the latitude as we near Europe...so next waypoint might be 60N/20W, or even
59N/20W dsepending on how the tracks were built for that day. By 15W we are getting close to Europe, so we revert to radar and VHF control....
IN a nutshell, that describes Trans Atlantic Ops...I mention that as background because, before GPS we relied on something called INS. In daylight,
when there were contrails to see, it was comforting to know that we were still on course, since we could see everyone else, above and below...
NOW, in addition to GPS, so very accurate, we also have TCAS, so we can see other airplanes, above and below us, within a range of 40 miles...
[edit on 6-3-2008 by weedwhacker]
[edit on 6-3-2008 by weedwhacker]
