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Questions tagged [contrails]

The white lines sometimes seen in the sky trailing an aircraft.

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62 votes
4 answers
12k views

How can a two-engine B787 create three contrails?

Today I noticed overflying aircraft (over Sydney at FL400) which appeared to have three contrails. When I checked Flightradar24 app, I saw that this overflying aircraft is B787. What would be the ...
kris's user avatar
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41 votes
4 answers
87k views

Why does an aircraft leave a white smoke trail?

Why does an aircraft leave a white smoke trail?
Tom's user avatar
  • 513
31 votes
3 answers
10k views

Is this contrail from an airplane or a rocket?

A relative of mine showed me the following picture that she took on the 11th of April, around 8 to 8:30 pm in the Netherlands somewhere near "Leiden" pretty close to Schiphol airport (unfortunately I ...
Remy's user avatar
  • 375
31 votes
3 answers
8k views

Do stealth airplanes need to limit contrail generation?

Stealth aircraft have low visibility on radar. I assume that they strive to achieve low visibility optically as well, e.g. spend some effort to not stand out too much visually from the surroundings. ...
florisla's user avatar
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29 votes
3 answers
8k views

Can helicopters create contrails?

Can some or all helicopters have contrails? If only some, why only those? If not, why can they not? Pictures would be really helpful. I do know that turboprops and piston props can leave contrails, ...
George's user avatar
  • 401
28 votes
4 answers
12k views

Do propeller planes give contrails like jets do?

Last weekend, while watching the second world war film "Fury" with a friend, there was a scene near the end with a large set of bombers flying overhead, leaving large contrails. That seemed wrong to ...
Gagravarr's user avatar
  • 389
28 votes
6 answers
7k views

Do jet contrails impact weather?

Do jet contrails impact weather at the ground?
anshabhi's user avatar
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24 votes
2 answers
5k views

Why are only some aircraft in this formation creating contrails?

The Republic Day celebrations at New Delhi, India had a series of flypasts by the Indian Air Force. What struck me the most was that in a formation with a C-17 in middle and two Su-30MKI flanking it, ...
Kanchu's user avatar
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21 votes
1 answer
4k views

Why are some contrails longer than others?

I've often noticed that planes flying on more or less the same track, headed in the same direction leaves different contrails. By different I mean how long they stay visible and the length of them. ...
Nicklas Pouey-Winger's user avatar
20 votes
2 answers
5k views

How does contrail formation differ from turbofan to turbojet?

Air forces and intelligence agencies are indeed interested in predicting whether condensation trails (contrails) will be visible or not during aircraft operations. Photo: C-CYOW at Photobucket Among ...
mins's user avatar
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18 votes
2 answers
3k views

How long does it take for a contrail to hit the ground? [closed]

I'm not even sure if they end up falling to earth, or if they accumulate and form/join other clouds or whatnot, which is part of the reason I'm asking this question. In contrails, heavier particles ...
Tyler's user avatar
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16 votes
1 answer
5k views

Do commercial flights continue with an engine out?

Do commercial flights continue with an engine failure? If you look closely at the attached picture it seems that one of the engines has a much smaller contrail than the other three. This seems to ...
Bruce Whiteside's user avatar
15 votes
3 answers
3k views

Why are contrails not visible from the cabin?

If you observe a plane flying whilst on the ground, plenty of times you will see contrails: Why are they not visible from the plane itself when sitting in the most rear part of the cabin even by ...
Fabrizio Mazzoni's user avatar
14 votes
6 answers
3k views

What causes pulses to appear in some contrails?

An aircraft at high altitude passed by faster and higher than normal, about 50% faster when compared to others in this recording. 2 mins later it appeared that half of the contrail developed right ...
Glyn's user avatar
  • 141
12 votes
3 answers
6k views

Were contrails different in the 80s?

My parents insist they remember contrails being significantly shorter around 1980s. From my research it seems this might be the result of several factors such as climate change, advancements in ...
OLEGSHA's user avatar
  • 231
12 votes
3 answers
9k views

What is the mechanism by which condensation forms above wings?

The planes landing at Sydney Airport have what looks to be sheets of steam pouring off the wings. Larger planes have multiple contrails while smaller regional planes only have these sheets. This is ...
Trigger's user avatar
  • 123
11 votes
3 answers
3k views

Can an APU exhaust make a contrail in flight?

I saw this picture in a local newspaper. My thoughts were, silly artists, that's the APU exhaust, it won't ever produce a trail like that during takeoff (or ever). Of course, the picture is clearly ...
Bart van Heukelom's user avatar
11 votes
1 answer
894 views

How do contrails form? [duplicate]

For my pre-scientific work I now need some general information about contrails. I searched for websites that explain the process of contrails being formed in detail but couldn't find any so far. I ...
Noah Krasser's user avatar
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10 votes
3 answers
4k views

Can we see evidence of "crabbing" when viewing contrails?

Can we see evidence of "crabbing" when viewing an aircraft leaving a contrail? Such as, in the form of an angular misalignment between the longitudinal axis of the aircraft (i.e. the ...
quiet flyer's user avatar
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9 votes
2 answers
4k views

Why don't the contrails show the curvature of the Earth?

When we see contrails in the sky, let's say traveling left/right in your vision, you are seeing across a sky that is easily a couple of hundred miles wide. I mean, we can see one side of space and ...
Chris's user avatar
  • 99
9 votes
2 answers
3k views

If jet engines did leave chemtrails, wouldn't the chemicals cause adverse reactions in the engines?

Please note, this question does not call into question whether or not the conspiracy theory is true or untrue, but the feasibility of certain chemicals being used as fuel additives in order to make ...
Tyler's user avatar
  • 927
9 votes
3 answers
582 views

Where do aerodynamical contrails get their condensation nuclei from, when forming at high altitude?

On this website, it is explained how aerodynamical contrails form: It’s formed by the reduction of pressure in the air as it moves over the wing. When the pressure of a gas falls, then its ...
Noah Krasser's user avatar
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8 votes
1 answer
1k views

777-300ER venting something from left engine outboard side - what is it?

Crossposting from Metabunk with permission from the thread opener marko.posavec. Their photo shows British Airways Boeing 777-300ER G-STBF in flight with something producing a contrail or the like ...
Cpt Reynolds's user avatar
  • 4,807
6 votes
1 answer
2k views

How to read the Appleman chart to predict contrail formation?

I stumbled upon the Appleman-chart, that makes it possible to predict the formation of contrails. How do I use this chart?
Noah Krasser's user avatar
  • 9,002
5 votes
1 answer
2k views

How does engine exhaust temperature affect contrail formation and why?

There was a german study about the "Influence of propulsion efficiency on contrail formation". In this study, an Airbus A340 and a Boeing 707 flew right next to each other. The two contrail forming ...
Noah Krasser's user avatar
  • 9,002
4 votes
2 answers
1k views

Have contrails ever occurred at low altitudes, such as at takeoff?

Contrails form from the exhaust of jet engines condensing to water-ice. Has this ever happened at low altitudes, especially during or immediately after takeoff?
DrZ214's user avatar
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4 votes
2 answers
1k views

How do contrails compare between piston-powered aircraft and jet aircraft?

Based off this question, I got interested on how contrails compare between jet engines and piston powered engines. Seeing images like these from WWII, I am wondering what the significant differences ...
SMS von der Tann's user avatar
3 votes
1 answer
156 views

Where do contrails that grow wider get their condensation nuclei from?

When a contrail occurs in a pure and over-saturated air in high altitude, it's also because of the engines emit condensation nuclei. But if the contrail expands in a wider cirrus, where do the ...
vmonteco's user avatar
  • 133
2 votes
0 answers
88 views

Why are some jet trails longer and some shorter? [duplicate]

One can see jet trails behind an airplane. I know that they form because of rapid condensation of Jet exhaust. But I can't figure out why some remain for too long time (hence, longer) while some are ...
Abhishek Verma's user avatar
1 vote
1 answer
884 views

Why is this plane flying in such a tight circle?

I was in a car in NYC on 2/18 going from Queens to Manhattan. While going over a bridge I noticed some (what looked to me like) very tight circular contrails in the sky. The plane was still there but ...
briantist's user avatar
  • 113
1 vote
1 answer
297 views

Why more contrails over Porto than Brisbane

I have family members hell bent on the Chemtrail conspiracy and aircraft spraying stuff on us. I’m trying to explain it’s to do with altitude, moisture and temperature. But I need a bit of help. We’re ...
Craig's user avatar
  • 129
1 vote
1 answer
44 views

Can I log a VFR XC toward 141 commercial license while simulating instrument

I flew last night with a friend to split time. Half the flight I wore foggles, half the flight he did So we could both be PIC And both have approach/landing practice. Could I log all of that ...
June's user avatar
  • 11
1 vote
0 answers
59 views

Can a weather forecast tell me if airplanes will leave long contrails? [duplicate]

Training 7 ball and 5 club juggling requires me to look up into the sky for durations of up to one minute. Frequently, this is very taxing on my eyes and, frustratingly, requires me to wear sunglasses....
Stephen Meschke's user avatar
0 votes
1 answer
96 views

Does aircraft nacelle length/shape/geometry affect the contrail formation?

This is coming from Question 1 and further down Question 2. I think the nacelle and exhaust cone do affect the contrail formation in some way, what is the relationship between them? Do the famous 787 ...
lousycoder's user avatar