A Dark Contrail near Salt Lake

Mick West

Administrator
Staff member
image.jpeg Source: https://youtu.be/O1WXIr92Wt8


Taken from Delta 4679 Jun 1 2016, looking North. Other plane seemed lower and was flying west

It was quite strikingly dark, might be useful to analyze the angles here to better understand why

The background was hazy.

Exif has GPS. Not sure what time zone iPhone was on.

f/2.2
1/2639 second
4 mm
121 mm (35 mm format)
ISO 32
Flash did not fire, compulsory flash mode
01-06-2016 01:01:15 PM
538.79 Miles per hour
38355.030437 feets above sea level (+/- 0.00)
0.00 EV
Auto exposure
Normal program
Auto white balance
Pattern Metering mode
Apple
iPhone 6
9.3.2
Apple
iPhone 6 back camera 4.15mm f/2.2
40.3122° -115.949°
 
Last edited:

Trailblazer

Moderator
Staff member
Annoyingly Nevada seems to be a bit of an ADS-B blackspot.

The GPS location of your photo is about here, in the untracked part of the flight.

upload_2016-6-2_11-21-31.png


Assuming the minutes part of the time was correct, it would have been at 11:01 PDT / 12:01 MDT, which is 18:01 UTC.

Trying to plot flights in that dead zone is pretty tricky. DL2638 could have been in the right area. This is 30 minutes after the probable time of your photo, and it is flying at 1,000ft lower than your flight, which was at 37,000ft (pressure altitude, which won't be the same as the GPS altitude in the EXIF).

upload_2016-6-2_11-45-47.png
 
Last edited:

Trailblazer

Moderator
Staff member
Assuming the time of your photo was 18:01:15 UTC, here are the relevant positions from the Flightaware track logs (times are in BST, ie UTC+1) :

DL4679 (your flight)


upload_2016-6-2_11-55-14.png



DL2638

upload_2016-6-2_11-51-39.png


The timestamps are 12 seconds apart, and the locations place DL2638 about 12 miles northwest of your flight.

upload_2016-6-2_12-0-49.png


I am not sure how accurate these positions are, presumably they are transmitted by the aircraft itself?
 

Trailblazer

Moderator
Staff member
@Mick West does the time sound right? It seems odd that the time shows up as 1:01pm, when the flight landed at 12:32pm (Mountain Daylight) or 11:32pm (Pacific Daylight). Your phone would have to have been set to Central Daylight time for that to make sense.

Or does the EXIF data show the time translated into your current time zone, perhaps?

With the flight duration only being just over an hour, there's no other XX:01 time that it could have been, and the location appears to agree with the EXIF.

upload_2016-6-2_15-12-10.png
 

Mick West

Administrator
Staff member
Yes, it was 18:01 UTC. The exif viewer was using my iPhone's current time zone (Iowa)
 
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