Discussion in 'Skydentify - What is that Thing in the Sky?' started by Pete Tar, Aug 6, 2014.
Interesting. It looks like a little dot cloud below the three commas is a part of the same formation. I'll try to triangulate it from these photographs tonight unless Mick or others do it before me
my first impression is that these look a bit like smoke rather than contrails, and they are actually climbing or falling rather than being horizontal - but I fully realise it is hard to gauge from the photos.
No, these appear to be genuine contrails. There are three pictures from the same user, J'am Harrison, that show their developments over time:
The Blue Angels and the Patriot Jet Team were appearing at Seafest 2014 in Seattle that weekend. Could be them en route, or any of the other event participants:
The 2nd picture (7-eleven) is looking pretty much directly North up 122nd from just south of the junction with Market Street (45.510843, -122.537942).
The 4th picture (Rent-A-Center) is looking North from 16353 SE Division St in Centennial (45.505384,-122.494726). This is about 4km East of where the 2nd picture was taken
The 1st picture, according to the photographer
This is a few km south of the 2nd picture (45.406887, -122.566223, approx). I can only assume Doug's photo has been reflected because the contrails are spreading to the left in his picture but to the right in all the others and yet they are all looking North.
Thanks for the info. I also have located the 4th picture and its viewing direction. This puts the location of the contrails north of Columbia river, somewhere in Washington state. Other mentioned places are further south from it. I'm looking for the photographs from other side, like Portland OR, or Vancouver WA. Finding a photo with a time stamp would be of a great help.
I've made a pseudo stereoimage of these contrails from these two pictures that are taken at approximately the same time from two locations 4 km apart and at approximately the same yet unknown distances from the contrails:
It shows that the three short tapered trails are horizontal and that the 'little dot' trail is in the same plane behind them (or ahead, if we assume that the planes were heading North, toward Seattle).
The same image with the inverted colours:
For the best viewing the image should be scaled so that the distance between the centres of its two parts was about 60-70 mm.
Reminds me very much of this:
Caused by aircraft descending through a layer of increasingly more humid air.
Not exactly horizontal, but no more than 5° or so.
I also recall this particular old case because it remains unfinished business to me. I think now that both cases may have similar explanations, as proposed above by jonnyH:
This new case seems fairly obviously three jets flying in formation. However I think the older set is still just regular air traffic.
Hmmm, I'm not so sure about that. We had thunderstorms that night, a spectacular sunset featuring cumulus and cirrus clouds, and some moisture pushing out ahead of it earlier in the day. Winds aloft were southerly so W-E advection would have been minimal. If the pictures were taken around 3 pm over Portland, then flights from the south beginning their descent into SeaTac would arrive around 30 - 45 minutes later. There are a series of arrivals into SeaTAc spaced just minutes apart from origins to the south.
3:30 pm AS359 Alaska Airlines Sacramento
3:33 pm DL1383 Delta Air Lines San Diego
3:34 pm DL2644 Delta Air Lines Los Angeles
There was a shallow layer of air that could support contrails at around 31,000 feet on radiosonde data from Salem, OR just south of Portland from the 8/1/00Z sounding which was 7/31 4:00 pm local time... the pics were taken around 3 pm.
9144 -37.0 -41.8 61 0.31 200
9356 -38.7 -43.3 62 0.27 198
9580 -40.5 -45.1 61 0.23 195
9741 -41.7 -46.4 60 0.20 195
9952 -43.5 -51.5 41 0.12 195
I think it was those three flights descending through a shallow layer of moister air just minutes apart.
Well, what bothers me with the older set is that all five contrails in it look about the same age, whereas my personal observations of individual tapered contrails show that their shapes change quite rapidly, within minutes.
This contradicts the apparent simultaneous evolution of these four contrails, including the shortest one behind the parallel three, see the picture in #4.
Yes, while the three flights are very close, they are spaced at +7 and +10 minutes.
(clock is an hour behind there)
It was not possible to deduce with confidence the location and altitude of these contrails from the pictures, as all of them turned out to have been taken from the same locality in practically the same (North) direction.
What was possible, due to a small variation of viewing angles, is to demonstrate that these contrails are horizontal and are viewed end on and directed toward Seattle. This reminds me our investigation of the Moscow Spiral Contrail, a horizontal twisted contrail, which also was viewed end on and looked like a piece of DNA double helix.
I could find no pictures of these contrails taken from very different angles. Presumably, none have been taken, because the short horizontal contrails would look ordinarily from the side.
As additional note, the FR24 playback of 31-July-2014 shows a noticeable gap in commercial flights along this route at the time of these contrails (around 3 pm PDT), that indirectly supports the JonnyH's suggestion above (#5).
I keep looking at the OP photo...seems apparent to me that three airliners (changing altitude) encountered an isolated region conducive to contrail formation. Subsequent to the first airplane, the short contrail it formed drifted with the prevailing winds aloft.
Airplane #2 (on the same ground track) makes another contrail, and and then, airplane #3. These three airplanes timed (or spaced, per ATC parlance) approximately equidistant from each other. (Because, the contrails formed, then were blown along the ground at an angle from the airplanes' course...almost equally spaced).
To help visualize this.....imagine a person blowing smoke rings, in a room with a slight draft....the smoke rings will be formed, and drift...and the person making them can 'time' them to appear in a pattern...sequentially.
ALSO....all three short contrail segments exhibit the SAME little "serif" at one end....indicative of a windshear situation. (Must have been some turbulence experienced onboard, by all three airplanes, at that point).
I think the idea they were sequentially laid is contradicted by trailspotter's post #4 showing them over a short period of time - their nature changes in unison so they must have been made at the same time. They also appear to be short-lived rather than persistant, so there would be much more 'degradation' from 1st to 3rd if they were made sequentially.
Oh, yes I see....well, a formation flight of three is also a valid hypothesis. As always, the more facts and documentation we have, the better the ability to analyze.
OK, after reviewing the FR24 playback at 2014-07-31 21:58 there are three planes in a row descending over the area just a few minutes apart. I think I was on the right track with sequential contrails, but they were different routes from what I had first guessed. I'm sticking with three sequential commercial planes.
They are in order:
DL 5782 SFO - SEA ETA 15:18
UA 1674 SFO - SEA ETA 15:21
AS 359 SMF - SEA ETA 15:23
Could be. They do seem remarkably similar to each other though.
The planes seem to be practically nose to tail in the right place at the right time.
Five minutes apart where the paths intersect:
(And I just noticed my previous images were for 8/1, not 7/31
It looks like I mistook the time of 3 pm PDT for 21:00 UTC Still, this is an unverified time from a single FB post. I will try to find some photos with exif data/time stamp from other sources (FB strips them from their pictures).
And another point. There seems to be the fourth plane ahead of the three but descending at about the same time as the others did. It left a very short trail, as seen in #4. I do not see a suitable candidate on FR24 just ahead of the three flights in your list.
A possible candidate is DL2644 with an ETA of 15:24 which was right behind that group of three. My wonky old computer isn't liking FR24 this morning but it looks like DL2644 was less than 5 minutes behind the other three passing over the Columbia river and one of the four probably descended through the contrail layer farther to the north but I can't tell which one. I'd like to see the flight paths for all 4 in 3-D over Portland, OR and Vancouver, WA.
DL 5782 SFO - SEA ETA 15:18
UA 1674 SFO - SEA ETA 15:21
AS 359 SMF - SEA ETA 15:23
DL 2644 LAX - SEA ETA 15:24
We need a candidate that was ahead a group of three. The shortest contrail is the furthest from the camera hence the closest to Seattle. Anyway, I've collected new evidence and will present it here later today (after I get back home).
Also, all three need to be making a crossing restriction that is very close to where these trails were made. Otherwise the odds of them all being on the same decent profile aren't likely. I mean, to be at the same altitude at the same position would be very unlikely unless they are trying to efficiently cross a point that is almost where the trails were made.
Would wind data from that time help?
Yes...it could be used to indicate whether the trails were carried by the winds aloft at a divergent angle from the track of the airplanes.
Or rather it will tell you how much the deviation is. It's very rare for there to be a zero sideways component of the wind at altitude.
Yes, and I included radiosonde data in a previous post. At 31,000 feet, winds were from the SSW from between 195 and 200 deg. so contrails were advected mostly from S-N with very little W-E advection so the trails from planes on a S-N route would be spaced closer together than one might think.
Like I said, the fourth plane may have descended through the contrail layer farther north of the other three. Just because it's father north does not mean it was made first. In fact, it looks like it could be newer than the other three.
All four candidates fly right over PDX one after the other... as if they were crossing a point like a navigational beacon?
Or, any waypoint. Could be a VORTAC, or an Intersection. If I take some time, I can determine the STAR (Standard Terminal Arrival) procedure that they were using, to look for the waypoints and altitude crossing restrictions (as mentioned by "captfitch" up above).
They were arriving at Sea-Tac? (KSEA).
Here is a link to FlightAware, and all the Instrument procedure charts:
Note in the list, the STARs:
OK...I'm back, having looked up Alaska #359 on 1 August 2014:
The flight plan shows they were filed for the HAWKZ THREE arrival ('RNAV' means 'Radio Navigation'...or GPS only, basically).
You can click on the Chart to "embiggen" it.
Arriving from the south, you can see that BTG VORTAC ('Battleground') has an altitude restriction of not below (proper term is "at or above") FL240. And waypoint PTERA at or above FL220.
Not sure if this helps. FlightAware can be used to check the other airliners' flight plans, see if they filed for the same arrival procedure.
Here's Delta ('DAL') 2644, 1 August:
United ('UAL') 1674 also:
ALL filed for the same arrival ('HAWKZ THREE'....or, also 'HAWKZ 3').
How do I put those tracks into google earth so I can view them from the locations of the various photographers?
I have found two photographs which are relevant to the case despite they do not depict these particular contrails.
The first is from Portland, depicting the Steel Bridge with some short tapered contrails above:
Alas, it is an instagram without exif data or time stamp. The arrangement of contrails is clearly different from OP and probably represents those from sequential descent of commercial planes. The location of the image is readily identifiable, adding it to GE shows the heading to these contrails is about 21° from the North.
This heading crosses the viewing line(s) from the OP pictures north of Battle Ground (WA):
The second picture is cropped from the Aqua satellite image of this area taken 7-31-2014 at 21:39 UTC.
It shows a short (only about 3 miles long) young contrail in this area and a couple of older short probable contrails further north. From the FR24 playback, the most likely candidate for the young contrail is ASA611 that descended through the spot at 21:31 UTC. It was at 31,000 ft at the time that suggests the probable altitude of shallow wet layer. The next flight SWA362 descended through the spot at 21:39, so its contrail would not have time to spread out to be seen by the satellite.
Putting the satellite and FR24 data on Google Earth shows that the image of the young contrail is about 13 km to the East of the plane route. The most of this distance (about 9 km) can be attributed to a non-orthogonal projection of the contrail to the ground (the satellite was to the West from the area at estimated altitude of 40-50°), the rest (4-5 km) to the contrail displacement by westerly wind. The pictures in #4 show that there was a westerly component of the wind.
The section of actual route shown in cyan, the contrail projection in magenta and its estimated location in blue.
I've raised these segments to altitude of 9 km on Google Earth and looked at them from the known locations.
There is a good agreement with the contrails from the bridge picture, but the three OP contrails appear higher and therefore closer to the camera. Only the shortest, fourth contrail looks a bit lower and further than the modelled one, but given a large margin of error in these fitting, it probably is in the same general area. Its non-descript shape suggests that the short contrails from commercial planes were formed too far to produce such a spectacular pattern in the area where the OP contrails have been observed.
I uploaded a kmz file (Short contrails OR|WA.kmz) with all these pictures and fittings.
You can download the attachments from the Mick's post (#22) and open them in Google Earth. I've done it and combined these tracks with my analysis in the previous post. The three planes past the spot, where a short contrail is seen on the Aqua satellite image, with a 90-second intervals, with the first one, DAL5782, flying higher than the other two. Together with the next flight(s), these flights may account for the contrail pattern in the Portland Steel Bridge photo, but, as I already said, this spot is too far from the area where the OP contrails were observed. The short contrails seen end on at that distance would look more like dots rather than lines. (Actually, there is another dot cloud in some of the OP pictures that could be the remnant of a short contrail.)
I would like to get the kml files of the Flightaware tracks for a few more flights of 7-31-2014:
DL2644 - the Sorley's fourth candidate;
ASA611 - my candidate for the Aqua satellite image;
DL5738 and SWA362 - the preceding and the next flights to ASA611
I'd appreciate it if some of the paid Flightaware users could provide us with copies of these files.
As there has been no new comments for while, i'd like to wrap up the tread with some concluding remarks.
Atmospheric conditions in the area at the time could support contrails:
The values for the altitude at which a layer of wet air resided (31000 ft) and the wind direction at this altitude (195-200°) are supported by the results of my analysis of the satellite and Flightradar24 data:
The contrails would drift in NNE direction, in agreement with the satellite image. These atmospheric conditions probably remained there for some time. As there is a busy air traffic route with planes descending to the SeaTac airport through this area, it can be expected that there were many other short parallel contrails on the day.
Indeed, it was the case. In addition to the picture of Steel Bridge in Portland depicting a set of short parallel contrails, I found another photo from Portland, taken on 2014:07:31 16:56:49 and geotagged to the Piedmont area:
Here is a crop from the original size photo, showing the remnants of up to seven such contrails:
They are seen in the downwind NNE direction and farther north than the older contrails in the satellite image.
The formation of three short parallel contrails by this scenario is very likely indeed, but would they look like the three contrails in OP? Or, which is more likely, they would look like the three parallel contrails in the photo by Alan Hansen (from the comments on FB page linked from OP):
two older contrails with staggered ends and a younger contrail separated by a larger distance?
I think that the last photo would account well for the contrails from the sequential flights identified by Sorley: two flights (UA 1674 and AS 359) with a short interval between them followed by a third flight (DL 2644) with somewhat longer interval. These three contrails appear to be lower in the sky and therefore farther away from the camera than the three contrails in OP The contrail from the earlier fourth flight (DL 5782) that descended farther away would be even lower and obscured by buildings or trees.
I would stick with the explanation of the OP contrails first proposed by Jonny H: three jets in formation descending through a layer of wet air in unison.
Thanks, those photos actually help make the case for THREE sequential descending flights at short intervals over the same area approximately just north of PDX, followed by a fourth (DL2644) a few minutes later. I speculated DL2644 might have produced the short contrail closer to the horizon.
DL 5782 SFO - SEA ETA 15:18
UA 1674 SFO - SEA ETA 15:21
AS 359 SMF - SEA ETA 15:23
DL 2644 LAX - SEA ETA 15:24
The Blue Angels, which consists of 6 planes, arrived a couple of days earlier, 7/28, and were practicing over the Seattle area/Lake Washington on the day in question, 7/31, so that rules out the Blue Angels.
http://www.seafair.com/Content/C75/2014 - Seafair Weekend Media Opportunities.pdf
The Patriots Jet Team, also 6 planes, were already in Seattle and busy on Thursday 7/31 with VIP schmoozing and photo-ops so that rules them out.
http://www.seafair.com/Content/C134/PATRIOTS JET TEAM 2014.pdf
The only other aerobatic team that performed at SeaFair 2014 was the Air National Guard Aerobatic Team and they probably would not be cruising at 31,000+ feet in the planes they fly like a bi-plane and Extra-300L's.
Well, the FlgthAware tracks for the first three flights, attached to #22, do not support this speculation. I looked at them in 3D, DL 5782 was flying higher that the other two and descended through 31000 ft farther north.
It might have produced the short contrail closer to the horizon. The other two flights might have produce the short contrails in the section shown by cyan bar. I do not have a FlightAware track for DL 2644, but the Flightradar24 playback suggests that it probably was similar to the other two tracks and past through the cyan bar section behind AS 359 with a larger time interval than the interval between UA 1674 and AS 359.
As for the three jets descending in formation, these may or may not be (a part of) an aerobatic team. Comments in the FB thread mention other fighter groups flying around earlier that day.
I've just stumbled upon a photo that reminded me this thread:
There are no doubts that these three parallel contrails are from the jets flying in formation.
Separate names with a comma.