As Distance Traveled in ISSR Decreases, RFContrails Decreases,

and RFExcessCO2Increases

As ISSR Avoidance Increases, Cost Increases and Total RF

Decreases per Flight Path

05E-121E-11

1.5E-112E-11

2.5E-113E-11

3.5E-114E-11

4.5E-11

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Tota

l Rad

iati

ve F

orc

ing

(W/m

^2)

ISSR Avoidance Percentage

Total RF (CO2 + Contrails Decreases with ISSR Avoidance)

Long Medium Short

Average Total RF vs. Average Cost per Flight Path

Contrails Cause Net Warming Effects When Summed Across All

Alights and All Conditions

RFContrails+ContrailInducedCirrus ≈ RFCO2 To reduce RF from contrails, ISSR can be avoided by strategic

flight planning

Avoiding ISSR may cause

increase in:• Excess distance flown

• Excess fuel consumption

• RF from excess CO2 emissions

• RF from contrail formation

Recommendations & Future Work

Design of a Flight Planning System to Reduce Persistent

Contrail Formation to Reduce Greenhouse Effects

Harris Tanveer, David Gauntlett, Jhonnattan Diaz, Po-Cheng Yeh

Context

Projected Growth in Air Travel Requires Attention to Climate

Impacts

Method of Analysis

Results

Problem & Need for ISSR Avoidance

• through

–

• around

–

Diaz, Gauntlett, Tanveer, Yeh

52

8.11 ! ! ! Emission Model

The following mathematical model will be utilized to calculate ! ! ! emissions for a

particular flight path:

! ! ! !! " #$$#%&= ! ∗ ! ,

! is the fuel consumed, c is a chemical constant (C02 produced by stoichiometric

combustion of known amount of fuel. ! = !3.175!! " !! ! !

! " !! " #$ ).

8.12 Contrail Model

In order to determine if persistent contrails will be formed, the following formula will be

used [3]:

! " #= ! " #6.0612! ! " .! " #! /(! " #.! " ! ! )

6.1162! ! ! .! " " ! /(! " #.! " ! ! )

RHi or relative humidity with respect to ice is a measure which allows the team to

determine if and when contrails will form. A value of over 100% means that persistent contrail

formation is considered favorable. The value RHw is relative humidity with respect to water, and

is obtained from the RAP data [3].

In order to estimate the contrail emission from the exhaust, the Schumann (2002) Ice

Water Content to ! ! ! will be used:

!" # ! ! ! ! = ! ! ! !! ! !100

−1

where ! ! is the density of air, ! ! is the saturation mixing ratio with respect to ice at the ambient

temperature, and ! ! ! is the percentage of relative humidity with respect to ice.

Diaz, Gauntlett, Tanveer, Yeh

52

8.11 ! ! ! Emission Model

The following mathematical model will be utilized to calculate ! ! ! emissions for a

particular flight path:

! ! ! !! " #$$#%&= ! ∗ ! ,

! is the fuel consumed, c is a chemical constant (C02 produced by stoichiometric

combustion of known amount of fuel. ! = !3.175!! " !! ! !

! " !! " #$ ).

8.12 Contrail Model

In order to determine if persistent contrails will be formed, the following formula will be

used [3]:

! " #= ! " #6.0612! ! " .! " #! /(! " #.! " ! ! )

6.1162! ! ! .! " " ! /(! " #.! " ! ! )

RHi or relative humidity with respect to ice is a measure which allows the team to

determine if and when contrails will form. A value of over 100% means that persistent contrail

formation is considered favorable. The value RHw is relative humidity with respect to water, and

is obtained from the RAP data [3].

In order to estimate the contrail emission from the exhaust, the Schumann (2002) Ice

Water Content to ! ! ! will be used:

!" # ! ! ! ! = ! ! ! !! ! !100

− 1

where ! ! is the density of air, ! ! is the saturation mixing ratio with respect to ice at the ambient

temperature, and ! ! ! is the percentage of relative humidity with respect to ice.

• •

•

Source: Form 41 and 298C, U.S. DOT 2005: 641 Tg/yr CO2 by Aviation Industry

• 4.2 million passengers/year

increase from 2013 to 2033

• 54.85% projected increase

in passengers from 2013 to

2033

Radiative Forcing (RF) -

energy/area 𝑊

𝑚2 difference

between incoming shortwave

radiation and outgoing longwave

radiation

Contrails + Induced

Cirrus RF ≈ 30

mW/m^2

Red: Travel Through ISSR

Blue: ISSR Avoidance

Contrail Induced cirrus

clouds may increase

Total Aviation RF by

41% (0.055 Wm-2 to

0.078 Wm-2)

Treat ISSR as “bad weather” areas to

maneuver around

Simulation Facts:

•Output: 54,000 flight

combinations

•Simulation uses 3-D

modified A* routing

algorithm

Tradeoff per Flight Path Between RFContrails and RFExcessCO2is

Based on CO2’s Contribution to Global CO2 Emissions and

Global RF

Independent Variables Outputs

Avoidance Aggression

Flight Length AtmosphericConfigurations

• Fuel Burn• CO2 emissions• Radiative Forcing (Contrails

and CO2)• Flight Distance• Flight Duration• %Distance in ISSR

No Avoidance

Short

45 days of weather from NOAA’s RUC

Database

Medium

Long

PartialAvoidance

Short

Medium

Long

CompleteAvoidance

Short

Medium

Long

Flight Length:

•Short: < 500 nm

•Medium: 500 – 1000 nm

•Long: > 1,000 nm

Long: 18.5% decrease from 0% to 100% Avoidance

Medium: 18.4% decrease from 0% to 100% Avoidance

Short: 18.1% decrease from 0% to 100% Avoidance

01E-122E-123E-124E-125E-126E-127E-128E-129E-12

0% 20% 40% 60% 80% 100%Rad

iati

ve F

orc

ing

(W/m

^2)

ISSR Avoidance Percentage

Radiative Forcing vs. ISSR Avoidance Percentage

Avg RF Excess CO2 (L) Avg RF Contrails (L)

RF Contrails

< RF ExcessCO2RF Contrails > RF ExcessCO2

At 99% Avoidance- Benefits of avoiding ISSR are outweighed by RFExcessCO2

for Long Flights

100

50

0

1.81.51.20.90.60.30.0

100

50

0

1.81.51.20.90.60.30.0

100

50

0

% DistISSR_Long, No Avoidance

% of Distance in ISSR

Pe

rce

nt

% DistISSR_Long, Complete

% DistISSR_Medium, No Avoidance % DistISSR_Medium, Complete

% DistISSR_Short, No Avoidance % DistISSR_Short, Complete

Histograms of % of Distance in ISSR by Avoidance Type

97% decrease in Average % of Distance in

ISSR

95% decrease in Average % of Distance in

ISSR

76% decrease in Average % of Distance in

ISSR

Long

Flights

Short

Flights

Medium

Flights

A

B

X

Y ZISSR

Origin

Destination

0

5E-12

1E-11

1.5E-11

2E-11

2.5E-11

3E-11

3.5E-11

4E-11

4.5E-11

$- $50.00 $100.00 $150.00 $200.00 $250.00

Ave

rage

To

tal R

F (W

/m^2

)

Average Cost (Fuel Cost in $)

Alternatives ComparisonNo Avoidance, Long

Partial Avoidance, Long

Complete Avoidance, Long

No Avoidance, Medium

Partial Avoidance, Medium

Complete Avoidance, Medium

No Avoidance, Short

Partial Avoidance, Short

Complete Avoidance, Short

Short Flights

Medium Flights

Long Flights

9 Alternatives with different Avoidance Aggressiveness and

Flight Lengths with 45 atmospheric combinations

% Decrease in Average Total RF (No Avoidance to

Complete Avoidance)

% Increase in Average Cost (No Avoidance to

Complete Avoidance)

Long Flight 18.49% 0.94%

Medium Flight 18.35% 1.33%

Short Flight 18.07% 4.14%

$-

$50.00

$100.00

$150.00

$200.00

$250.00

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Fue

l Co

st (

$)

ISSR Avoidance Percentage

Fuel Cost vs ISSR Avoidance

Long Medium Short

Long: 0.94% increase from 0% to 100% Avoidance

Medium: 1.33% increase from 0% to 100% Avoidance

Short: 4.14% increase from 0% to 100% Avoidance

Recommendation:

Pilot testing should be

conducted at 99% ISSR

Avoidance for Long, Medium,

and Short distance flights

Future Work:

• Who should pay for increased fuel and crew costs as distance increases?

• How is passenger comfort impacted from ISSR avoidance

• How can ISSR avoidance be combined with wind optimal flight paths

Systems Engineering & Operations Research, George Mason University

𝐅𝐮𝐞𝐥 𝐂𝐨𝐧𝐬𝐮𝐦𝐩𝐭𝐢𝐨𝐧 = 𝜂 × Thr × 𝐶𝑓𝑐𝑟

𝐂𝐎𝟐 𝐄𝐦𝐢𝐬𝐬𝐢𝐨𝐧𝐬 = 𝑓 ∗ 3.175

𝐑𝐞𝐥𝐚𝐭𝐢𝐯𝐞 𝐇𝐮𝐦𝐢𝐝𝐢𝐭𝐲 𝐰𝐢𝐭𝐡 𝐑𝐞𝐬𝐩𝐞𝐜𝐭 𝐭𝐨 𝐈𝐜𝐞

𝑅𝐻𝑖 =6.0612𝑒18.102𝑇/(249.52+𝑇)

6.1162𝑒22.577𝑇/(273.78+𝑇)

𝑹𝑭𝑪𝒐𝒏𝒕𝒓𝒂𝒊𝒍𝒔 𝒕 = 𝑓𝑙𝑖𝑔ℎ𝑡𝑠 𝑅𝐹𝐿𝑊+𝑆𝑊 𝑡,𝑠 𝑊 𝑡,𝑠 𝑑𝑠

𝑆𝑢𝑟𝑓𝑎𝑐𝑒 𝐴𝑟𝑒𝑎𝐸𝑎𝑟𝑡ℎ

𝑹𝑭𝑬𝒙𝒄𝒆𝒔𝒔𝑪𝑶𝟐 =𝐸𝑥𝑐𝑒𝑠𝑠 𝐶𝑂2

641 𝑇𝑔 𝐶𝑂230

𝑚𝑊

𝑚2