BBC - Longer flights to curb vapour trails

Article from the BBC website that discusses the extra fuel needed to avoid producing persistent contrails could have less of impact on the global climate than the trails themselves.

http://www.bbc.co.uk/news/science-environment-27907399

I am going to preempt that this means the conspiracists have won. Too many people are now noticing these trails that they have had to come up with an excuse to stop producing them. Woo, yeah, fight the good fight.
 

Mick West

Administrator
Staff member
Here is the actual study:
http://iopscience.iop.org/1748-9326/9/6/064021/article

This is not really anything new, suggestions for avoiding contrail areas have been around for a while. Here's a similar paper from 2011
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110008150_2011007211.pdf

And 2005:
http://dspace.mit.edu/handle/1721.1/32460
Another:
http://dspace.mit.edu/bitstream/handle/1721.1/85768/871330199.pdf?sequence=1


Back in 2002 there were suggestions for flying lower - as it's always been known you could avoid contrails by simply reducing altitude.
http://www.tandfonline.com/doi/abs/10.3763/cpol.2003.0328#.U6L7v2Qv-Gk

The extra fuel has always been an issue with that, so a fine-tuned computer controlled system has always looked like the best bet. IBM patented such as system in 2008 - although they describe increasing contrail cover in some places and decreasing it in others, to modulate energy usage from AC and heating on the ground.
http://www.google.com/patents/US20090319164
Similar article on the Daily Mail, which has started to put actual science in little Orange boxes
http://www.dailymail.co.uk/sciencet...r-conditions-help-prevent-global-warming.html
The comments there have a lot of chemtrail folk, who are also discussing the science on Twitter:
 
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Steve Funk

Senior Member.
Has anyone really done the math on this? If there are no contrails, the main emission is gaseous water vapor, which is a more effective greenhouse gas than CO2. If there are contrails, the contrail cirrus clouds consisting of frozen water droplets, have mixed effects, trapping heat but also reflecting sunlight. The graph that has been posted a couple of places on this site shows a large degree of uncertainty on the effects of contrail cirrus.
 
No. and No.
Maybe you misunderstand me but one of the comments on the Daily Mail site already confirms this

 
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Mick West

Administrator
Staff member
Has anyone really done the math on this? If there are no contrails, the main emission is gaseous water vapor, which is a more effective greenhouse gas than CO2. If there are contrails, the contrail cirrus clouds consisting of frozen water droplets, have mixed effects, trapping heat but also reflecting sunlight. The graph that has been posted a couple of places on this site shows a large degree of uncertainty on the effects of contrail cirrus.
They have certainly done some math, and are aware of uncertainties.

http://iopscience.iop.org/1748-9326/9/6/064021/article
Don't expect such discussion in the Dail Mail (or even the BBC) :)
 

deirdre

Senior Member.
Maybe you misunderstand me but one of the comments on the Daily Mail site already confirms this

all the article does is concur with everything the debunkers have been saying for years. That contrails are due to Weather Conditions and altitude. That contrails are too long (mass size) to be "chemtrails" and that contrails are just manmade clouds, that sometimes spread out just like clouds do.
 
all the article does is concur with everything the debunkers have been saying for years. That contrails are due to Weather Conditions and altitude. That contrails are too long (mass size) to be "chemtrails" and that contrails are just manmade clouds, that sometimes spread out just like clouds do.
Yeah, but if you expect the conspiracists to accept that then you are sorely mistaken. Cos they can easily come up with excuses like the one I suggested. And they will do.

At some point you have to realise you are arguing for the "no win" team and they are arguing for the "no lose" team. Although ultimately there are no winners.
 

Hama Neggs

Senior Member.
Article from the BBC website that discusses the extra fuel needed to avoid producing persistent contrails could have less of impact on the global climate than the trails themselves.

http://www.bbc.co.uk/news/science-environment-27907399

I am going to preempt that this means the conspiracists have won. Too many people are now noticing these trails that they have had to come up with an excuse to stop producing them. Woo, yeah, fight the good fight.
From that article:

I think they have those two numbers reversed.
 

Hama Neggs

Senior Member.
Yeah, but if you expect the conspiracists to accept that then you are sorely mistaken. Cos they can easily come up with arguments like the one I suggested. And they will do.

At some point you have to realise you are arguing for the "no win" team and they are arguing for the "no lose" team. Although ultimately there are no winners.
It is true that you can't stop people who are determined and willing to make up nonsense. to support their position. The bunk machine never sleeps. :rolleyes:
 

deirdre

Senior Member.
Yeah, but if you expect the conspiracists to accept that then you are sorely mistaken. Cos they can easily come up with excuses like the one I suggested. And they will do.

At some point you have to realise you are arguing for the "no win" team and they are arguing for the "no lose" team. Although ultimately there are no winners.
that's ok. I'd rather be right. Plus all the cool guys are on my side.. the scientists and astronauts and jet fighter pilots etc.
 

David Fraser

Senior Member.
While the paper is very interesting it will not change the appearance of those lines in the sky as it is only applicable to intercontinental flights. I hazard a guess that diverting traffic is impractical for EU domestic airspace.
 

WeedWhacker

Senior Member
It's important to note that Flight Planning scenarios (especially very long-range) involve other more important considerations than just "avoiding" the production of a contrail.

(And yes, this is a type of "Chicken Little says 'The sky is falling!' " example of false hysteria, the "concern" about contrails).

The prevailing forecast winds for the route can have a significant effect on flight times, and thus fuel burn rate. Also, many airlines use predicitve tools to help avoid turbulence en-route as much as possible. All of these considerations result in compromises, sometimes....then there also sometimes ATC-mandated routing procedures.....
 

Mick West

Administrator
Staff member
While the paper is very interesting it will not change the appearance of those lines in the sky as it is only applicable to intercontinental flights. I hazard a guess that diverting traffic is impractical for EU domestic airspace.
One of the other papers suggests that shorter flights should fly at lower altitudes, a different type of trade-off.
 

WeedWhacker

Senior Member
One of the other papers suggests that shorter flights should fly at lower altitudes, a different type of trade-off.
That actually might need to become a "norm" in EU airspace, just merely because of the congestion. And for shorter flights, the increase in amount of fuel used is only slight....however as with everything, it does add up flight-by-flight.

The general consensus was, even for very short lengths, to go as high as possible. Examples such as Houston (Texas) to Austin. About 30 minutes total, lift-off to landing. Yet we'd typically file for altitudes such as 32,000 or 34,000 feet. And, about one minute after reaching the cruise altitude, we'd then begin the arrival descent. So, the theory is yes you've been running the engines at high power setting for about 15 minutes in the climb, but then they are mostly at or near idle during the last 15 minutes.
 

David Fraser

Senior Member.
One of the other papers suggests that shorter flights should fly at lower altitudes, a different type of trade-off.
Just reading a paper cited in the original post http://www.aviationsystemsdivision.arc.nasa.gov/publications/2013/ATM2013_Sridhar_Final.pdf

The concluding remarks are interesting in that they note that altitude changes on an "as and when" basis are more fuel efficient than a permanent reduction in altitude.

However just from reading information on here, for Europe, what would be the day to day practicalities especially with regards for air traffic control and how much fuel etc.
 

Balance

Senior Member.
From that article:

I think they have those two numbers reversed.
Nope, read it again.;) They are saying theoretically, an aircraft could divert by as much as 10x distance before the fuel emissions outweighs the contrail emissions in terms of damaging the climate. ie, 10km of fuel burnt has the same warming effect as 1km contrail

ETA: "Ladies and gentleman, this is your captain speaking. Our new contrail-aversion system estimates our arrival time will be extended by a factor of nine. Have a nice flight."
 
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Mick West

Administrator
Staff member
Nope, read it again.;) They are saying theoretically, an aircraft could divert by as much as 10x distance before the fuel emissions outweighs the contrail emissions in terms of damaging the climate. ie, 10km of fuel burnt has the same warming effect as 1km contrail
Yes, that's the conclusion of the paper:
http://iopscience.iop.org/1748-9326/9/6/064021/article
 

Hama Neggs

Senior Member.
Nope, read it again.;) They are saying theoretically, an aircraft could divert by as much as 10x distance before the fuel emissions outweighs the contrail emissions in terms of damaging the climate. ie, 10km of fuel burnt has the same warming effect as 1km contrail

ETA: "Ladies and gentleman, this is your captain speaking. Our new contrail-aversion system estimates our arrival time will be extended by a factor of nine. Have a nice flight."
OK, I see it now, but that hardly seems practical.
 

Mick West

Administrator
Staff member
OK, I see it now, but that hardly seems practical.
No it's not, but that's was just the upper bound. The paper suggests much more modest course alterations can be used, especially on longer flights. Like here, an extra 22km across the Atlantic:
 

Balance

Senior Member.
And it all hinges on contrail-formation predictions. Can't see it flying imho (excuse the pun) or is the science that good now?
 

Trailspotter

Senior Member.
Will the persistent contrail have the same climate impact regardless what lays below: a landmass or an ocean? Would be there any gain from the contrail avoidance if the ground below is already obscured by a cloud layer?
 

Mick West

Administrator
Staff member
Will the persistent contrail have the same climate impact regardless what lays below: a landmass or an ocean?
Probably. It's going to depend on the albedo and emissivity of the ground/sea, and various other factors.

Would be there any gain from the contrail avoidance if the ground below is already obscured by a cloud layer?
The climate effect they want to prevent is warming (or rather a reduction in cooling) this happens at night. It's quite complicated - but yes, existing cloud will have an effect. They would have to model all kinds of factors to arrive a optimum routes.
 

WeedWhacker

Senior Member
No it's not, but that's was just the upper bound. The paper suggests much more modest course alterations can be used, especially on longer flights. Like here, an extra 22km across the Atlantic:
That diagram becomes impractical because of the NAT system.


So, every parallel NAT Track would need to be adjusted with the same "bend" in the route, to maintain the required lateral separation (One degree of Latitude, about 60 Nautical miles).

Note that there is a procedure (since 2004) called "SLOP" --or, Strategic Lateral Offset Procedure" but this limits parallel route offsets to 1 or 2 miles.
 

Mick West

Administrator
Staff member
Yeah, it would require replacing the NAT system with some kind of satellite based computer controlled ATC that can freely route planes. Rather a significant undertaking.
 

Hama Neggs

Senior Member.
And since flights are already in the air when an alteration of a subsequent flight was wanted, it all sounds hopelessly complicated.
 

Mick West

Administrator
Staff member
And since flights are already in the air when an alteration of a subsequent flight was wanted, it all sounds hopelessly complicated.
The complexity is easily solved by computers, however it requires an integrated system, so they can avoid hitting each other. Such a system will probably happen this century, and tacking on contrail mitigation/creation would be an incremental feature.
 

deirdre

Senior Member.
The complexity is easily solved by computers, however it requires an integrated system, so they can avoid hitting each other. Such a system will probably happen this century, and tacking on contrail mitigation/creation would be an incremental feature.
wouldn't it be easier to just build nuclear plants or windmill farms for developing countries?
 

Mick West

Administrator
Staff member
wouldn't it be easier to just build nuclear plants or windmill farms for developing countries?
No. Computerised air traffic is going to happen. Weather monitoring and forecasting happens. So it's reasonably cheap (compared to building a nuclear power station) to do some programming to link them to modulate contrails.

I don't think it's a huge factor though, just another tool in the arsenal.
 

Hama Neggs

Senior Member.
The complexity is easily solved by computers, however it requires an integrated system, so they can avoid hitting each other. Such a system will probably happen this century, and tacking on contrail mitigation/creation would be an incremental feature.
I suppose, but any gains would be marginalized by having planes which haven't taken the altered routes from takeoff having to change course to accommodate for changes on other flights, shifting the entire fleet around all the time. It seems like it would be a case of diminishing returns.
 

KC-10FE

Senior Member.
I will say this: The #1 factor when it comes to our flight planning (besides safety of course) is fuel savings. I would guarantee the airlines are the same way. We are ALWAYS trying to fly high and at optimum airspeed in order to save fuel. If we are flying into select military bases, they even take away our fuel required for an alternate, since there are so many other fields nearby. At no time have we compromised this in order to create less contrails in the skies, the only pilots I have known who care about that issue are the B2 Stealth pilots, since it factors into their visibility while flying, for obvious reasons.
 

deirdre

Senior Member.
I will say this: The #1 factor when it comes to our flight planning (besides safety of course) is fuel savings. I would guarantee the airlines are the same way. We are ALWAYS trying to fly high and at optimum airspeed in order to save fuel. If we are flying into select military bases, they even take away our fuel required for an alternate, since there are so many other fields nearby. At no time have we compromised this in order to create less contrails in the skies, the only pilots I have known who care about that issue are the B2 Stealth pilots, since it factors into their visibility while flying, for obvious reasons.
the gov. will have to give them tax credits. cause yea, hurting the economy just makes the climate issue worse.
 

WeedWhacker

Senior Member
....the only pilots I have known who care about that issue are the B2 Stealth pilots, since it factors into their visibility while flying, for obvious reasons.
Yeah, good point.

Contrails ARE a consequence of burning fossil fuels in certain temperature/atmospheric conditions.

PERIOD!!

(This is going out to any in the public who might be enjoying this thread discussion). The very concept of "Stealth" (such as B-2 bomber, the F-117, or any other future design) is harmed when the very engines that these jets need, burning NORMAL jet fuel, can give away your position!!
 

Mick West

Administrator
Staff member
I suppose, but any gains would be marginalized by having planes which haven't taken the altered routes from takeoff having to change course to accommodate for changes on other flights, shifting the entire fleet around all the time. It seems like it would be a case of diminishing returns.
The computers would account for that. There is plenty of room in the sky if you know exactly where everyone is.
 

WeedWhacker

Senior Member
The computers would account for that. There is plenty of room in the sky if you know exactly where everyone is.
AGAIN.....this is the (very near future) concept of what has been proposed (for the future) and dubbed "Free Flight".

Yes, this WILL be the way of the future for air travel. It will evolve. There are huge obstacles in that path to 'evolution'...but it will, one day, be commonplace. (**)

EDIT: Only one of a few problems I can foresee will be (as usual) the Human element. NO system or method is "perfect". Technology can account for much of (expected) Human error....but not ALL of it.

(**) Just as, back when I started in aviation, there was no such thing as GPS. We adapted the technology, it improved many aspects of aviation. Such improvements WILL continue, moving forward in time.
 
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MikeC

Closed Account
EDIT: Only one of a few problems I can foresee will be (as usual) the Human element. NO system or method is "perfect". Technology can account for much of (expected) Human error....but not ALL of it.
and that is why the aircrew of the future will be just 1 pilot and a dog - the pilot's job is to feed the dog, and the dog's job is to bite the pilot if s/he tries to touch anything.
 

Ross Marsden

Senior Member.
I recall a contrail mitigation study that concluded that persistent contrails could be avoided 80% of the time with an altitude change of less than 2000 feet. A note on how to take into account the aircraft induced cloudiness in the EU-ETS (see pages 6 and 7).

A lowering of altitude into warmer air, where contrails will not form at all, is pretty sure-fire but you would burn much more fuel.
You could also climb into (possibly) drier air and avoid persistent contrail conditions. That will invite bring other dangers, like "coffin corner" where the aircraft's safe airspeed range is seriously diminished between high-speed buffet and low-speed stall. (A pilot could expand a bit on this.)

Diverting horizontally seems the hard way to do it. The atmosphere is quite delicately layered, so a change in altitude is the way to go. IMO.
 

WeedWhacker

Senior Member
and that is why the aircrew of the future will be just 1 pilot and a dog - the pilot's job is to feed the dog, and the dog's job is to bite the pilot if s/he tries to touch anything.
Old. Joke. (And I am old enough to recall when it first came out...).
 
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