MEMORANDUM

TO: Bryan Manning, EPA Office of Transportation and Air Quality (OTAQ)

FROM: Richard Billings

Eastern Research Group, Inc. (ERG)

DATE: April 6, 2015

SUBJECT: Documentation of Quality Checks Implemented and Peer Review Process for 

Small Jet Fuel Use and Carbon Dioxide (CO2) Emissions Inventory

1.0 Introduction

ERG developed an emission inventory of aircraft and helicopters equipped with engines that 

burn jet fuel that will not be required to comply with carbon dioxide standards being developed 

by International Civil Aviation Organization’s (ICAO) Committee on Aviation Environmental 

Protection (CAEP). A preliminary dataset and report was completed in December 2014 and 

provided to the EPA for review. 

In addition to EPA’s and ERG’s internal review, two independent consultants were 

commissioned to conduct an external review to assess the methodology, data sources, and results 

of the preliminary data.

This memorandum summarizes the internal quality checks that were implemented along with 

documentation of the peer review process. The external reviewers’ comments and observations 

are documented in a separate report that compiles all comments and revisions made to the 

report. In addition to this memorandum, the peer review record includes:

• Jet Fuel Use and CO2 Emissions Inventory for Aircraft below ICAO GHG Program 

Thresholds - Draft Report with compiled external review comments.

• Jet Fuel Use and CO2 Emissions Inventory for Aircraft below ICAO GHG Program 

Thresholds - Final Report.

2.0 Internal Quality Checks

To ensure the quality of data used in the study and reasonableness of the results, the following 

quality assurance checks were implemented:

1
• Checked data compilation to ensure that the datasets matched the original dataset and 

were not corrupted during data transfer. No issues with data transfer or transcription were 

found.

• Compared landing and takeoff (LTO) fuel usage rates to aircraft average data to identify 

and evaluate aircraft that were significantly different for the average values. LTO fuel 

usage was only used for the T-100 data that were applied to Emissions and Dispersion 

Modeling System (EDMS), which includes separate fuel usage data for aircraft 

make/model engine make/model combinations. No alternative LTO fuel usage data 

sources were identified or used in this study.

• Compared CO2 fuel fractions found in EDMS (9.75 kg CO2/gal), the 2008 Climate 

Leaders GHG Guidance (9.57 kg CO2/gal) (EPA, 2008), the 2014 EPA Fast Facts: 

National-Level U.S. Greenhouse Gas Inventory summaries (EPA, 2014b), and the 2015 

draft Inventory of U.S. GHG Emissions and Sinks report (9.75 kg/CO2) (EPA, 2015). The 

EPA recommended using the 9.75 kg/CO2 because it is based on the most recent data and 

is consistent with the EDMS factor. 

• Ensured that the LTO data used in the EDMS runs matched the data compiled from the 

T-100 data.

• Compared fuel usage rates for cruising to Project Interactive Analysis and Optimization 

(PIANO) data provided by the EPA. The PIANO fuel usage rate data were applicable to 

only aircraft above the maximum takeoff mass (MTOM) threshold and were not used 

directly in this assessment of aircraft below the MTOM threshold.

• Assessed the fraction of CO2 emissions associated with the aircraft relative to total jet 

CO2 emissions in the 2015 draft Inventory of U.S. GHG Emissions and Sinks (2015) and 

Fast Facts: National-Level U.S. Greenhouse Gas Inventory (EPA, 2014).

• Compared the aircraft counts from the General Aviation and Air Taxi Activity (GAATA)

survey, the FAA Registry, and the Ascend database.

Table 2-1 shows general Quality Assurance assessment factors and how they were considered in 

this study. 

2
Table 2-1. QA Summary Table

General 

Assessment Factor Definition How the Factor was Considered

Soundness The extent to which the scientific and 

technical procedures, measures, 

methods or models employed to 

generate the information are 

reasonable for, and consistent with, the 

intended application. 

ERG used accepted inventory 

procedures to compile available 

data and calculate emissions. The 

emission calculations follow 

similar methods used in the 

EPA’s 2011 National Emission 

Inventory. 

Applicability and 

Utility

The extent to which the information is 

relevant for the Agency’s intended 

use.

There is no singular data source 

currently available to quantify 

aircraft counts and activity levels 

for aircraft with MTOM below 

the CO2 standard thresholds. To 

get the required data, T-100 

datasets, which includes aircraft 

make and model-specific 

information were used in 

conjunction with the FAA EDMS 

model to identify commercial 

aircraft below the thresholds. 

GAATA data along with aircraft 

registration data were used to 

quantify non-commercial aircraft 

(though adjustments were needed 

to account for air taxis which 

would appear in both studies. 

Clarity and 

Completeness

The degree of clarity and 

completeness with which the data, 

assumptions, methods, quality 

assurance, sponsoring organizations,

and analyses employed to generate the 

information are documented.

Throughout the process, data 

were provided to the EPA to 

show how the datasets were 

being developed, including 

summary comparisons and 

analysis.

The quality checks implemented 

in this study were included in the 

project Quality Assurance Project 

Plan (QAPP).

This document, in conjunction 

with the project datasets, was

developed to allow for 

independent replication of the 

procedures used.

3
Table 2-1. QA Summary Table

General 

Assessment Factor Definition How the Factor was Considered

Uncertainty and 

Variability

The extent to which the variability and 

uncertainty (quantitative and 

qualitative) in the information or in the 

procedures, measures, methods or 

models are evaluated and 

characterized.

The data used in this study were 

either detailed and specific (such 

as the T-100 and EDMS factors)

or highly aggregated (such as the 

GAATA activity data); making it 

difficult to quantitatively assess 

uncertainty. 

To the extent possible, 

information is provided in the 

report to qualitatively indicate 

whether the data over- or underestimated actual fuel usage or 

emissions. 

Evaluation and 

Review

The extent of independent verification, 

validation and peer review of the 

information or of the procedures, 

measures, methods, or models.

Internally, data were reviewed at 

critical points of the project to 

insure that data were compiled 

and calculations were 

implemented correctly.

The EPA implemented a 

comprehensive review of the 

report and data; all recommended 

changes are included in memo. 

Glenn McDonald and Peter 

Zimm from ICF and an 

independent contractor, Ralph 

Rissmiller of RR Aviation 

Services, LLC, provided an

external review of the 

methodology used and 

preliminary results. Suggested 

changes were addressed in the 

current version of this report.

External Peer Review

The peer review process began in December 2014 and was completed in February 2015. The 

EPA Work Assignment Manager identified three external independent reviewers who have 

experience with aviation emission inventory studies and who have active support contracts with 

4
OTAQ. These reviewers were provided with a copy of the draft report and associated data. The 

peer reviewers were asked to draw upon their expertise in small aircraft, as well as in GHG

emission estimation methods, to comment on whether the data inputs, approach, and 

methodologies presented in the draft report reflect sound scientific and analytical practice, and 

adequately quantified the fraction of CO2 emissions associated with aircraft below the ICAO 

GHG reporting thresholds. Table 3-1 identifies the peer reviewers participating in the review 

and their organizational affiliations. No changes were recommended for the data developed in 

this study.

Table 3-1. External Independent Peer Reviewers

Reviewer Affiliation

Glenn Mc Donald

Peter Zimm

ICF

Ralph Rissmiller RR Aviation Services, LLC

The peer reviewers provided written responses to the EPA Work Assignment Manager 

who provided them to ERG for consideration in revising the approach or documentation. 

These comments were summarized in a spreadsheet that indicated the reviewer, page/line 

number, draft text for which the comment is associated, the question/issue, and response. 

Table 3-2 of this memorandum summarizes these comments and responses.

Note, the peer reviewers did not provide any recommendations or suggestions that required 

changes to the project dataset.

5
Table 2. Comment/Response to the Draft

Commenter Page Section Text Comment Response

Glenn 

McDonald/ 

Peter Zimm

1.0 General Comment

It might be helpful to outline the 

overall methodology visually in a 

diagram in Section 1.0 Chart added

Glenn 

McDonald/ 

Peter Zimm

General Comment

Possibly an issue with word docs 

being converted to PDF, but there 

are a few issues in font 

standardization and word spacing Checked PDF files for issue

Glenn 

McDonald/ 

Peter Zimm

General Comment Define acronyms first time using 

(GAATA, GHG, QA/QC, etc.)

Checked acronyms to ensure they 

are all defined when first mentioned 

in the text

Glenn 

McDonald/ 

Peter Zimm

3 General Comment

Might be helpful to state that LTO 

cycles and cruising time are on 

annual basis

Annual time notation included in the 

text

Ralph 

Rissmiller 5 1.0

In addition, CAEP’s applicability 

thresholds exclude piston-engine aircraft 

and helicopters, and since CAEP 

requirements only apply to civil aircraft, the 

aircraft CO2 standard also does not apply to 

military aircraft.

The footnote indicates that pistonengine aircraft operate on aviation 

gasoline, however a growing 

number may be operated on Jet-A 

fuel (i.e., diesel powered pistonengine aircraft).

Footnote updated with this 

information

Ralph 

Rissmiller 5 1.0

In addition, CAEP’s applicability 

thresholds exclude piston-engine aircraft 

and helicopters, and since CAEP 

requirements only apply to civil aircraft, the 

aircraft CO2 standard also does not apply to 

military aircraft.

Helicopters are powered by both 

aviation gasoline and Jet-A fuel.

For applicability purposes both fuel 

types would still be excluded. No 

change required.

Ralph 

Rissmiller 5 1.0

In addition, CAEP’s applicability 

thresholds exclude piston-engine aircraft 

and helicopters, and since CAEP 

requirements only apply to civil aircraft, the 

aircraft CO2 standard also does not apply to 

In my opinion, these aircraft 

generate a proportionally larger 

amount of CO2 emissions due to 

their generally lower fuel 

efficiency than a comparable 

Good point, but this is a discussion 

of applicability and military aircraft 

are not included in the standard. No 

change required.

6
Table 2. Comment/Response to the Draft

Commenter Page Section Text Comment Response

military aircraft. commercial aircraft.

Ralph 

Rissmiller 6 1.0

To ensure the products for this project align 

with data used in the Emission and Sinks 

document, data obtained from the Federal 

Aviation Administration’s (FAA) 2012 

General Aviation Part 135 Activity Surveys 

(GAATA, 2013) was assumed to be fuel 

purchased and used within the U.S.

I believe this is generally correct, 

however a significant number of 

business jets and turboprops are 

operated under Part 91 (not 135). 

There are also specific 

organizations that operated some 

of their flights under Part 91 and 

some under Part 135 criteria. For 

example, NetJets (a large 

fractional operator) operates under 

Part 91 Subpart K.

Clarifying text added

Glenn 

McDonald/ 

Peter Zimm

1

General Comment The GAATA survey covers Part 

91 and On-Demand Part 135, 

while the T-100 data set covers 

Part 121 and Part 135 operators 

with more than $20M in annual 

revenue. It seems that there is both 

an overlap and a gap between the 

two data sets. Some overlap will 

occur between GAATA and T-100 

for large On-Demand Part 135 

operators with more than $20M in 

annual revenue, but neither 

database will cover smaller Part 

135 Scheduled operators with 

<$20M in revenue. Some 

additional discussion or sensitivity 

analysis on the magnitude of this 

missing data would be helpful for 

Clarifying text added

7
Table 2. Comment/Response to the Draft

Commenter Page Section Text Comment Response

the reader. It’s likely that the 

inclusion or estimation of this data 

will not drastically change the 

emissions forecast; however, 

scheduled Part 135 operators 

generally have high utilization and 

thus will materially contribute to 

total fuel burn and emissions.

Ralph 

Rissmiller 6 1.0

The GAATA data include all activity (by 

aircraft type) for general aviation and air 

taxis, while the T-100 data include 

commercial activity by specific aircraft 

make and model, which include air taxis 

but not non-commercial general aviation.

It appears this is intended to cover 

Part 91 and 135 operations, and T100 data covers air carriers, but 

not totally clear. The following 

phrase is what creates my 

question. It says that T-100 data 

includes air taxis (and air carrier), 

but not non-commercial general 

aviation. The preceding statements 

imply that the FAA data report 

includes Part 91 as well as Part 

135 commercial/air taxi 

operations. I’d suggest clarifying 

if possible. From the text, I got the 

idea that the commercial/air taxi 

small aircraft were included in 

both reference reports.

Clarifying text added

8
Table 2. Comment/Response to the Draft

Commenter Page Section Text Comment Response

Ralph 

Rissmiller 6 1.0

For turboprops, the aircraft make and 

model from the T-100 data above and 

below the MTOM threshold were 

determined using the MTOM listed for 

each aircraft make and model in the FAA’s 

Emissions Dispersion Modeling System 

(EDMS) system tables (FAA, 2013).

There are very few noncommercial operators in the US of 

turboprop aircraft with a MTOM 

>8618 kg, with most <5700 kg. 

The vast majority of the general 

aviation turboprop aircraft are 

<8618 kg.

Good validation of our results. No 

change required

Ralph 

Rissmiller 7 2.0

For base year 2012, the T-100 activity data 

include air time and LTO by specific 

aircraft make and model (FAA, 2012). 

It may be worth considering that 

aircraft utilization decreased 

during 2012-2014 due to 

economic concerns.

SOW is limited to data availability at 

the time that the project was being 

implemented; there was only partial 

data for 2014. Variance in activity 

from year to year is noted in the 

projections section. No change 

required.

Ralph 

Rissmiller 8

2.0 -

Table 

2.1

Table 2-1. The Number of Aircraft in each 

Aircraft Category

I believe this table needs some 

work. The weight numbers don’t 

match up with the EDMS category 

statements. I also question the 

number of models indicated for 

the very heavy large and medium 

business jets (around 400-750K 

lbs). There are only a very few 

business jets in this weight class. 

The vast majority are <70K lbs, 

with only the very largest 

approaching 120K lbs. It appears 

that a number of the large Boeing 

and Airbus aircraft are being 

included.

The table categories were check and 

the MTOM values listed in the tables

represent the smallest aircraft size 

reported in EDMS for the aircraft 

categories used in EDMS. Though 

they do not exactly match the values 

used in the CO2 standard threshold, 

they are relatively close and useful 

for our purposes.

No change required to weight class 

numbers, but text was added that 

individual aircraft MTOM may be 

different than the average values 

presented in Table 2-1. 

9
Table 2. Comment/Response to the Draft

Commenter Page Section Text Comment Response

Note Table 2-1 includes all aircraft, 

including those above and below the 

CO2 standard thresholds. For our 

purposes only helicopter and small 

turboprop data are needed in this 

analysis, the others presented in 

Table 2-1 are above the ICAO GHG 

threshold and included as they 

needed to be evaluated to determine 

if they are considered air taxi’s and 

should be removed from the 

GAATA estimates. The larger 

aircraft categories were removed 

from the table as they are unlikely to 

include air taxis. 

Glenn 

McDonald/ 

Peter Zimm

General Comment In Section 1.0, the methodology 

for reconciling the turboprop fleet 

and utilization between T-100 and 

GAATA is a bit unclear. By 

definition of the weight class 

rules, it’s likely that all (or at least 

the vast majority) of turboprop 

operations with GAATA are from 

aircraft less than the MTOM 

threshold, while some of the T100 turboprop data is likely from 

aircraft greater than the MTOM 

threshold. The subtraction of the 

T-100 data from the GAATA data 

is therefore a bit unclear. Thus, it 

Clarifying text added

10
Table 2. Comment/Response to the Draft

Commenter Page Section Text Comment Response

seems likely that the small 

turboprop operations were 

underestimated by removing more 

GAATA data than appropriate.

Ralph 

Rissmiller 8

2.0 -

Table 

2.1

Propeller Not clear to me what this category 

actually includes. Is it the 

reciprocating engine fleet?

Added general aviation category text

Ralph 

Rissmiller 8

2.0 -

Table 

2.1

Large Business Jet – Average MTOM This may be biased slightly 

towards the large business jet class 

(i.e., Bombardier Challenger and 

Global Express, Gulfstream, and 

larger Dassault aircraft). A 

substantial number of the smaller 

jet aircraft are <25,000 lbs 

MTOM.

Noted in the text that individual 

aircraft MTOM may be different 

than the average values presented in 

Table 2-1

Ralph 

Rissmiller 8

2.0 -

Table 

2.1

Large Business Jet – Number of Aircraft 

Models

The only general aviation “large 

jet” aircraft are Boeing and Airbus 

aircraft, and there are only a 

handful in service as general 

aviation aircraft.

These are commercial air taxis that 

are considered large jets in EDMS. 

No change required.

Ralph 

Rissmiller 8

2.0 -

Table 

2.1

Medium Jet – Number of Aircraft Models I am not aware of a population of 

16 aircraft models that would be 

categorized as medium jet 

business aircraft in this weight 

class. This is approaching the 

weight of an A330 or B767. In 

general, the largest general 

aviation business aircraft are in the 

100,000-130,000 lbs MTOM 

range, while the majority of the 

Removed from table as they are 

unlikely to include air taxis.

11
Table 2. Comment/Response to the Draft

Commenter Page Section Text Comment Response

larger long range business jets are 

in the 70,000-90,000 lbs MTOM 

class.

Ralph 

Rissmiller 8

2.0 -

Table 

2.1

Medium Jet – Average MTOM There are only a handful of large 

business jets in the weight 

categories of 758,550 and 391,760 

lbs (Boeing and Airbus business 

jets). The vast majority of aircraft 

in these weight classes are large 

commercial transport aircraft. 

Removed from table as they are 

unlikely to include air taxis.

Ralph 

Rissmiller 8

2.0 -

Table 

2.1

Small Jet – Average MTOM The average weight of 176,724 lbs 

does not fit the small jet category. 

Is this an error in labeling? It 

appears that the 37,567 small jet 

and 176,724 lbs business jet 

values may be reversed.

Checked data, average is correct –

no change required

Ralph 

Rissmiller 8 2.0

Because the Quest Kodiak 100 did not have 

aircraft information in EDMS, a 

comparable value was used from a similar 

aircraft in EDMS. 

There are only a small number of 

these aircraft in service at this 

time. This aircraft is quite similar 

to the Cessna 208 Caravan.

Surrogate changed

Glenn 

McDonald/ 

Peter Zimm

8

General Comment Appears to be a typo on 1 ton = 

0.0005 lbs

Correction made

Glenn 

McDonald/ 

Peter Zimm

General Comment The GAATA survey should 

include the vast majority of the 

U.S. helicopter fleet, as nearly all 

helicopter operations are classified 

as Part 91 or On-Demand Part 

135. Total utilization for this fleet 

is available from GAATA as well. 

Clarifying text added

12
Table 2. Comment/Response to the Draft

Commenter Page Section Text Comment Response

ICF believes that the GAATA 

“total hours by aircraft type” Table 

3.2 is meant to represent total 

aircraft flying hours, not just 

cruising hours. Similarly, the fuel 

burn gallons per hour is meant to 

be an average per-hour burn rate 

over the entire flight, not just for 

cruise. Thus, it seems that

the “T100 and GAATA Fuel Burn 

and CO2

Emissions_12_18_2014.xlsx” 

model might be overestimating the 

rotorcraft fuel burn numbers by 

double counting the cruise and 

LTO portions of the flight. The 

total hours and average fuel burn 

per hour rates appear to include 

the portion of fuel burned during 

LTO. ICF suggests reviewing the 

rotorcraft fuel burn output on the 

“GAATA” worksheet and setting 

the total rotorcraft fuel burn to 

509,339 tons (the current cruise 

figure), instead of adding in the 

459,346 tons from the additional 

LTO estimation.

Ralph 

Rissmiller 9

2.0 -

Table 

2.2

Eurocopter AS350 B2 AStar SA350 

TPE331-3 TPE3 Weight factors based 

engine market share

Why is this the only helicopter 

listed? There are a large number of 

Hughes, Bell, Sikorsky, etc. 

This is the only helicopter reported 

into the T-100 dataset. No change 

needed.

13
Table 2. Comment/Response to the Draft

Commenter Page Section Text Comment Response

helicopters in service. Also 

Robinson (R66) has a turbine 

powered version as well.

Note that T-100 data may not 

include all aircraft as they only 

account for commercial air carriers. 

The GAATA data were included as 

they include non-air carrier service 

providers such as medivac 

helicopters, offshore support, 

pipeline surveillance and traffic 

monitoring helicopters

Ralph 

Rissmiller 9

2.0 -

Table 

2.2

Socata TBM850 There are additional TBM models 

as well.

These are the only models reported 

into the T-100 dataset. Checked that 

International data were included.

Note that T-100 data may not 

include all aircraft as they only 

account for commercial air carriers. 

The GAATA data were included as 

they include non-air carrier service 

providers which use these smaller 

aircraft

Ralph 

Rissmiller 9

2.0 -

Table 

2.2

Beech C99 What about the Beech 90 series 

(90, A90, B90, C90), 100 series 

(100, A100, B100) snf 300/350 

series?

These are the only models reported 

into the T-100 dataset. Checked that 

International data were included.

Note that T-100 data may not 

include all aircraft as they only 

account for commercial air carriers. 

The GAATA data were included as 

14
Table 2. Comment/Response to the Draft

Commenter Page Section Text Comment Response

they include non-air carrier service 

providers which use these smaller 

aircraft

Ralph 

Rissmiller 9

2.0 -

Table 

2.2

Pilatus PC-12 I do not see the PC9 listed. These are the only models reported 

into the T-100 dataset. Checked that 

International data were included.

Note that T-100 data may not 

include all aircraft as they only 

account for commercial air carriers. 

The GAATA data were included as 

they include non-air carrier service 

providers which use these smaller 

aircraft

Ralph 

Rissmiller 9

2.0 -

Table 

2.2

Above the MTOM Threshold I do not see the Piper Meridian 

(single engine turboprop) listed.

These are the only models reported 

into the T-100 dataset. Checked that 

International data were included.

Note that T-100 data may not 

include all aircraft as they only 

account for commercial air carriers. 

The GAATA data were included as 

they include non-air carrier service 

providers which use these smaller 

aircraft

15
Table 2. Comment/Response to the Draft

Commenter Page Section Text Comment Response

Ralph 

Rissmiller 12

2.0 -

Table 

2.4

Table 2-4. Aircraft and Engine Specific 

Emission Factors from EDMS Run

The table doesn’t indicate which 

of the aircraft are single engine

and which are multi-engine. This 

may be adequately addressed in 

the fuel consumption rate, so just 

an observation.

See earlier comments regarding 

additional aircraft models not 

included in the table (i.e., Beech 

90/200/300 series, PC-9, Piper 

turboprop, etc.).

The number of engines was not a 

critical component in this study as 

the calculations were based on 

individual aircraft movements, 

EDMS automatically accounts for 

different engine configurations. No 

change required.

Ralph 

Rissmiller 12 2.0

The comparable aircraft selected was 

EADS Socata TBM-700/ PT6A-64.

I would have suggested a 

comparable aircraft is the Cessna 

208 Caravan.

Surrogate changed.

Ralph 

Rissmiller 13

2.0 -

Table 

2.5

Normally, fuel consumption is 

considered in lbs/hr (not lb/min), 

although it is a simple conversion.

To calculate emissions from cruising 

units need to be in terms of mass, not 

volume. No change required.

Glenn 

McDonald/ 

Peter Zimm

General Comment Prior to table 2.6, it might be 

helpful to give some more detail 

on how minutes were allocated 

between LTO and cruise (see 

Helicopter Fleet/Utilization 

Reconciliation as well)

Table added of Time in Mode 

assumptions used

Ralph 

Rissmiller 16

3.0 -

Table 

3.1

Turbo Jet/Turbo Prop – Up to 5,669* Should this be the “a” footnote 

reference instead of “*”?

Correction made

Ralph 

Rissmiller 17

3.0 -

Table 

3.3

Small Business Jet 315.1 I believe this consumption rate is 

more typical of the larger business 

jets (i.e., >30K lbs MTOW. The 

smaller business jets (like the 

Observation noted in the text

16
Table 2. Comment/Response to the Draft

Commenter Page Section Text Comment Response

Citation 500 series which are 

around 12-25K lbs) would more 

likely average around 1,000 lbs/hr 

(or approx. 125 gph).

Ralph 

Rissmiller 17

3.0 -

Table 

3.3

Helicopter 54.7 Does this include all helicopters or 

only the AStar listed above?

Also, not clear if this column is 

per engine or per aircraft (i.e., 

single or multi engine). I realize 

this may not be a factor, since I 

believe fuel consumption is being 

addressed as per airplane. If so, 

then it is addressed that way.

Clarification made to title 

Ralph 

Rissmiller 19

3.0 -

Table 

3.5

Table 3-5: 2012 T-100 and GAATA 

Combined Fuel Use and CO2 Emission 

Estimates by Aircraft Type and Mode

Need to update table with T-100 

international Segment

Update included

Ralph 

Rissmiller 19 4.0 4.0 Comparisons Under development Comparison included

Ralph 

Rissmiller 19 4.0 Parts of the comments below the table are not visible.

Table will be replaced

Ralph 

Rissmiller 20 5.0

To estimate anticipated future emissions 

from small business jet, turboprop, and 

helicopter activities, projected general 

aviation fuel usage data were obtained from 

the FAA’s Aerospace Forecast, 2014-2034 

(FAA, 2014b). 

I recognize this is an FAA 

publication, however I believe the 

projected growth is rather large 

considering the current fleet 

growth rate.

The projections in the report are 

consistent with the projections in the 

FAA Aerospace Forecast. No change 

needed.

Ralph 

Rissmiller 20 5.0

Table 5-2 summarizes projected CO2

emissions for small business jets, 

turboprops, and helicopters, based on the 

2012 CO2 emissions and the growth factors 

Should this be Table 5-1? Correction made

17
Table 2. Comment/Response to the Draft

Commenter Page Section Text Comment Response

included in Table 5-1. 

Ralph 

Rissmiller 22 6.0

Assessed the fraction of CO2 emissions 

associated with the aircraft relative to total 

jet CO2 emissions in the EPA Emission and 

Sinks report and Fast Facts: National-Level 

U.S. Greenhouse Gas Inventory (EPA, 

2014b).

Pending inclusion of international 

segment of T-100 data.

Completed

18