U.S. Department

of Transportation

FEDERAL AVIATION

ADMINISTRATION

Office of Aviation Policy and Plans

Washington, D.C. 20591

 

FINAL REGULATORY EVALUATION 

ACTIVATION OF ICE PROTECTION 

(14 CFR Part 121)

OFFICE OF AVIATION POLICY, PLANS AND MANAGEMENT ANALYSIS 

AIRCRAFT REGULATORY ANALYSIS BRANCH, APO-320

George Thurston

June 29, 2010
2

TABLE OF CONTENTS

I. INTRODUCTION 3

II. BACKGROUND 3

III. THE COSTS ESTIMATE 5

IV. THE BENEFITS ESTIMATE 19

V. BENEFIT-COST SUMMARY 24

VI. APPENDIX 
3

I. INTRODUCTION

This final rule will amend the regulations applicable to operators of certain airplanes used 

in § 121 air carrier service and certificated for flight in icing conditions. The standards will 

require either the installation of ice detection equipment or changes to the Airplane Flight 

Manual (AFM) to ensure timely activation of the airframe ice protection system. This final rule

is the result of information gathered from a review of icing accidents and incidents, and it is 

intended to improve the level of safety when airplanes are operated in icing conditions. This 

final rule is also responsive to National Transportation Safety Board (NTSB) recommendation 

A-07-14. 

II. BACKGROUND

On October 31, 1994, at 15:59 Central Standard Time, an Avions de Transport Regional 

model ATR-72, operated by Simmons Airlines, Incorporated, and doing business as American 

Eagle flight 4184, crashed during a rapid descent after an uncommanded roll excursion. The 

plane crashed into a soybean field near Roselawn, Indiana. The FAA, Aerospatiale, the French 

Direction Générale de l’Aviation Civile, Bureau Enquete Accident, National Aeronautics and 

Space Administration (NASA), National Transportation Safety Board, and others conducted an 

extensive investigation of this accident. This investigation concluded that freezing drizzle 

conditions created a ridge of ice aft of the deicing boots and forward of the ailerons, which 

resulted in uncommanded roll of the airplane. 
4

This accident and investigation prompted the FAA to initiate a review of aircraft in-flight

icing safety and determine changes that could be made to increase the level of safety.

In May 1996, the FAA sponsored the International Conference on Aircraft Inflight Icing, 

where icing specialists recommended improvements to increase the level of safety of aircraft 

operating in icing conditions. The FAA reviewed the conference recommendations and 

developed a comprehensive multi-year icing plan. The FAA Inflight Aircraft Icing Plan, dated 

April 1997, described various activities we were contemplating to improve aircraft safety when 

operating in icing conditions. In accordance with the FAA Inflight Aircraft Icing Plan, the FAA 

tasked the Aviation Rulemaking Advisory Committee (ARAC), through its Ice Protection 

Harmonization Working Group (IPHWG), to consider the need for ice detectors or other 

acceptable means to warn flight crews of ice accretion on critical surfaces requiring crew action. 

In November 2009, the FAA published a notice of proposed rulemaking (NPRM) for part 

121 Activation of Ice Protection. The comment period for the proposed rule closed February

2010. The FAA’s response to economic comments is contained in the preamble to this final rule.

This final rule is based on the ARAC’s recommendations to the FAA. The final rule will

require either the installation of ice detection equipment or changes to the Airplane Flight 

Manual (AFM) to ensure timely activation of the airframe ice protection system.

II.1. NTSB Safety Recommendations 

This final rule addresses NTSB safety recommendation A-07-14 on the subject of 

airframe icing. That NTSB safety recommendation resulted from a Cessna Citation 560 series 

airplane accident near Pueblo, Colorado, which occurred on February 16, 2005, in which the 

airplane crashed and eight people died. The accident airplane had been operating in icing 
5

conditions and the flight crew had not activated the airframe ice protection system during 

approach as required by the AFM for the operational conditions. The NTSB recommended that 

manufacturers and operators of pneumatic-deicing-boot-equipped airplanes be required to revise 

their operating manuals and training programs to emphasize that leading edge deicing boots 

should be activated as soon as the airplane enters icing conditions.

III. THE COSTS ESTIMATES

III.1 Discussion of the Final Rule

The final rule consists of two parts:

(1) 14 CFR part 121.321 Sections (a)(1), (a)(2), or (a)(3) which will affect all part 121 

operated airplanes with a certified MTOW of less than 60,000 pounds. These 

sections will mandate when the pilot is to activate the Ice Protection Systems (IPS). 

All part 121 airplanes certificated for flight in icing conditions, currently have an IPS. 

A primary or advisory ice detection system (IDS) is a device that alerts the flight 

crew to activate the IPS. Not all part 121 airplanes certificated for flight in icing 

conditions, have IDS. For airplanes equipped with an IDS, this final rule will allow 

either automatic or manual cycling by the flight crew each time ice is detected. For 

airplanes not equipped with an IDS, this final rule will mandate that when the 

airplane is operating in conditions conducive to airframe icing, the IPS must be 

activated prior to and operated during all phases of flight except take-off and cruise 

(unless prohibited by the AFM). Conditions conducive to airframe icing is defined as 

visible moisture at or below a static air temperature of +5 degree C or a total air 

temperature of +10 degree C.
6

(2) 14 CFR part 121.321 Sections (b), (c), (d), and (e) which affects all 14 CFR Part 121 

operated airplanes with a certified MTOW of less than 60,000 pounds. These 

sections will mandate adding the procedures for safe and continuous operations of the 

IPS in the AFM.

Two elements drive the overall cost estimate. They are:

(1) the costs per airplane to the operators required to implement sections (a)(1), (a)(2), or 

(a)(3) of this final rule; and

(2) the estimate of the number of affected airplanes; including a snapshot of the current 

active fleet, a forecast of airplanes affected by the final rule entering the fleet, and a 

forecast of the retired affected airplanes during the analysis period.

If the AFM prohibits the procedures of (a)(3)(i), then section (b) specifies procedures. 

Section (c) requires AFM procedures for compliance with the final rule. Section (d) requires 

procedures for operating an IPS after its initial activation. Section (e) requires approval of 

system installations and Airplane Flight Manual procedures through an amended or supplemental 

type certificate. The costs for section (b), (c), (d) and (e) are included in the costs estimated for 

section (a)(1), (a)(2), or (a)(3) of this final rule.

All costs, discussed in the following estimates, are based in 2010 dollars and the present 

value discount rate is seven percent as mandated by the Office of Management and Budget. We 

also performed a sensitivity analysis with a three percent present value factor. The FAA 

analyzed the costs and benefits of this final rule over a 20-year analysis period after the 

promulgation of the final rule. A 20-year analysis interval would capture nearly all of the 

lifetime costs and benefits of the final rule.

III.2 Assumptions
7

In order to estimate the potential costs and benefits of the final rule, we have made the 

following assumptions:

(1) The base year is 2010.

(2) This final rule will be effective in 2011.

(3) The compliance date of the rule is 24 months from the effective date of the final rule.

(4) The analysis period extends for 20 years from 2013 through 2032. We believe this 

analysis period captures nearly all of the expected benefits and costs.

(5) All monetary values are expressed in constant 2010 dollars. The present value of the 

potential 10-year benefit stream was calculated by discounting the monetary values using a 

three and seven percent present value rate over the 2013 to 2032 analysis period.

(6) The value of an averted fatality is $6.0 million.1

(7) The FAA used $104.99 hourly rate for a mechanic/technician working for an airplane 

manufacturer or modifier and the $86.48 hourly rate for an engineer working for an airplane 

manufacturer or modifier. These hourly rates include overhead costs.2

III.3 Costs Required to Implement Sections (a)(1), (a)(2), or (a)(3)

Exhibit 1 illustrates the chain of events leading up to the decision on whether an operator 

will incur the cost of a primary ice detection system, an advisory ice detection system, or activate 

the IPS’s when entering conditions conducive to airframe icing. 

 

1

“Treatment of the Economic Value of a Statistical Life in Departmental Analysis”, March 18, 2009, U.S. 

Department of Transportation Memorandum.

2Department of Labor, Bureau of Labor Statistics. Occupational Employment and Wages,
8

For section (a)(1), (a)(2), and (a)(3) of the final rule, the costs include:

(1) Indirect Non-recurring Airplane Group Costs

(2) Direct Operator Costs.

To determine the indirect non-recurring costs, we requested and the IPHWG provided 

system design, system certification, updating the AFM, flight tests and retrofit costs. These 

IPHWG provided indirect costs are shown in Appendix C1, C2, and C3.

To determine the direct costs to operators to implement sections (a)(1), (a)(2),or (a)(3) of 

the final rule, the analysis required distinguishing each airplane by having either one of two ice 

detection systems installed, or having no ice detection system installed. To satisfy the intent of 

section (a)(1) or (a)(2) of the final rule, each of the airplane groups were analyzed to determine if 

they currently had:

(1) a primary ice detection system (a)(1), or

Does the Airplane 

have a Primary Ice 

Detection System?

(a)(1)

Does the Airplane

have an Advisory Ice 

Detection System and 

Visual

Cues?

(a)(2)

Yes

No No

Yes

Airplane is Compliant

Cost = $0.00

Airplane is Compliant

Cost = $0.00

Cost = 

min[(a)(1),(a)(2), 

or a(3)] 

 

Exhibit 1

Cost of (a)(1), (a)(2), or (a)(3) Compliance
9

(2) an advisory ice detection system installed, along with visual cues (a)(2).

If the airplane had either one of the two options, then the intent of section (a)(1) or (a)(2)

has been satisfied and operators of these airplanes will not incur additional compliance costs 

from this final rule. If an airplane does not have either one of the two options, then when the 

airplane is operating in conditions conducive to airframe icing, the operator must either install a 

primary or advisory ice detection system or section (a)(3) mandates that the ice protection system

must be activated prior to and operated during all phases of flight except take-off and cruise 

(unless prohibited by the AFM). 

The following sections will discuss the indirect non-recurring and direct costs associated 

with section (a)(1), (a)(2), and (a)(3) We provide cost estimates for section (a)(1), (a)(2), and 

(a)(3) and discuss why (a)(3) is the low-cost alternative for the final rule.

III.4 Section (a)(1) and (a)(2) - Indirect Non-recurring Airplane Group Costs

If the decision is made to install a primary or advisory ice detection system, nonrecurring costs consist of the following:

(1) System Design – includes ice detector system architecture and integration, 

positioning, and updating the manufacturer’s AFM procedures;

(2) System Qualification/Certification – includes ice detector qualification, certification, 

and flight test; and

(3) Tasks associated with the retrofit – includes service bulletin preparation, approval and 

a crew-training program.

III.5 Section (a)(1) and (a)(2) – Direct Operator Costs 

Direct operator costs are defined herein as:
10

(1) The purchase of Primary or Advisory Ice Detection system,

(2) The installation of the Primary or Advisory Ice Detection system,

(3) Pilot Training costs, and

(4) Updating the operator’s AFM.

The IPHWG, operators and industry associations provided the FAA with the costs of 

purchasing and installing primary or advisory ice detection systems for the airplanes affected by

this final rule.

3

 These costs are shown in Appendix C1 and C2. 

III.6 Section (a)(3) - Indirect Non-recurring and Direct Operating Costs

There are three non-recurring operator costs associated with continuously operating the 

IPS during all phases of flight except take off and cruise. They are:

(1) Updating the manufacturer’s AFM for each major airplane group, 

(2) Updating the operator’s AFM for each major airplane group, and

(3) Flight tests.

The non-recurring costs were distributed equally across each of the operator’s airplanes 

in each of the operator’s major airplane groups. These costs are shown in Appendix C3. Note

the more airplanes in a major airplane group, the lower the non-recurring average costs are to the 

operators of those airplanes. The converse is also true. We believe operators will follow the 

timeframe listed in § 121.321 and incur these costs 24 months after the effective date of the final 

rule.

Since (a)(3)(i) effectively will increase the usage of IPSs, then this final regulation will

increase costs of maintenance and of replacement of the IPSs. In order to estimate the increased 

 

3The IPHWG provided costs in 2002$ and we escalated the costs to 2010$ based on inflation. To account for inflation, we used 

current dollar and real GDP figures for 2000-2010 from the Bureau of Economic Analysis (BEA) website.
11

maintenance costs and the increased frequency of replacing the IPSs, the FAA reviewed the 

currently issued Airworthiness Directives (ADs) concerning activation of the IPS and how the 

ADs differed from this final rule.

The ADs in Docket Number 99-NM-137-AD through 99-NM-145-AD, 99-NM-147-AD 

through 99-NM-154-AD, and AD 2001-06-18 require airplane operators of certain4airplanes to 

activate the pneumatic wing and tail deicing boots at the first sign of ice accumulation. The final

rule will require the operators to activate the pneumatic wing and tail deicing boots when visible 

moisture is at or below a static air temperature of +5 degrees C or a total air temperature of +10 

degrees C. When the IPS is operated based on visible moisture and temperature, there might not 

be ice accumulating on the airframe. Thus, the final rule is more conservative than the current 

ADs issued because the IPSs will be activated even though ice may not be accreting on the 

airframe.

The IPHWG provided data from one operator who claims that the increased use of the 

IPS mandated by the ADs in Docket Number 99-NM-137-AD through 99-NM-145-AD, 99-NM147-AD through 99-NM-154-AD, and AD 2001-06-18, would drop the average service life of a 

pneumatic deicing boot from 4 years to 2-2.5 years. From further consultations with industry

associations and operators of affected airplanes, we discovered this final requirement will further 

drop the average service life of a pneumatic deicing boot to one year. 

We averaged the IPHWG, industry associations and operators of affected airplanes 

provided cost estimates to develop the cost basis for this final rule. The ADs added an additional 

$287 per month, per airplane in maintenance and replacement costs to operate the IPSs. For 

airplanes subject to the ADs, the further increase of boot usage due to the final rule will add an 

additional $464 per month, per airplane and certification and initial operator costs of about 
12

$19,500 per airplane group or type. The IPHWG, industry associations and operators of affected 

airplanes estimate the final rule will not need additional flight tests for airplanes subject to these 

ADs. Appendix C3 shows these costs.

For airplanes which are not subject to the ADs and are operating the deicing boots based 

on flight crew observation of a specific thickness of ice, the increased deicing boot usage will 

add $751 per airplane, per month. These additional costs are shown in Appendix C3 and include 

boot maintenance, replacement and installation labor and are the only recurring costs estimated 

over the analysis period. Also, for airplanes which are not subject to the ADs and are operating 

the deicing boots based on flight-crew observation of a specific thickness of ice, there will be 

$17,295 for system design procedures and $360,927 for flight tests. Those costs are estimated to 

be about $378,222 per airplane group and are also shown in Appendix C3.

Section (a)(3) will also require that each U.S. certificated operator provide training for 

pilots and copilots of airplanes to comply with procedures mandated by the final rule. The FAA 

accepts the IPHWG’s estimate of two hours of initial training per pilot or copilot, one hour to 

update the AFM, and ten pilots per airplane. At $104.99 per hour training costs,5the FAA 

estimates that the initial cost of training will be about $2,205 per affected airplane. The training 

costs estimated are one-time fees incurred in the first year the final rule becomes effective.

III.7 Section (b) – Airplane Flight Manual (AFM)

Section (b) of the final rule states that if the procedures in section (a)(3) are prohibited in 

the AFM, then compliance must be shown with the requirements of section (a)(1) or (a)(2). The 

 

4Note: not all airplanes affected by this final rule were subject to the icing AD’s.

5

Ice Protection Harmonization Working Group (IPHWG) of the Aviation Rulemaking Advisory Committee 

(ARAC) escalated to 2010$.
13

FAA has found no case where the procedures in section (a)(3) are prohibited in the AFM for 

airplanes affected by the final rule. Therefore, section (b) adds no costs to the operators. 

III.8 Section (c), (d) and (e)

Costs for section (c), (d) and (e) of the final rule are embedded in the estimates for 

sections (a) and (b).

III.9 Estimating the Number of Affected Airplanes

The cost estimates discussed above are per-airplane costs. To obtain a total cost estimate, 

these per airplane costs are multiplied by the number of airplanes; hence, the fleet of affected 

airplanes must be estimated. To estimate the number of affected airplanes, the FAA analyzed the 

current active fleet of airplanes, a forecast of airplanes affected by the final rule entering the 

fleet, and a forecast of the retired affected airplanes exiting the fleet during the analysis period.

A list of all U.S. operated civilian airplanes operating under 14 CFR Part 121 was 

generated by the FAA Flight Standards Group.6

We determined that all newly delivered part 121 airplanes will either have a primary or 

advisory ice detection system and therefore will be compliant with the final rule. Hence, we 

concluded that future deliveries of new airplanes, affected by this final rule, will be compliant 

and incur no costs.

Each airplane group was matched with its current (as of May 2010) Maximum Take-Off 

Weight (MTOW) and average age through the use of the OAG FleetPC database.

 

6 NVIS Air Operator Database; May 2010
14

All airplanes with a certified MTOW greater than 60,000 pounds were eliminated, 

leaving 2,136 airplanes in the active fleet to be subject to the final rule.

Using industry sources, the FAA determined which affected active airplanes had primary

or advisory icing detection systems.

Table 1 details the number of affected part 121 turboprop and turbojet airplanes, their 

average age, and their ice detector equipage status.

The ATR 42, ATR 72, CRJ, DHC-8, Dornier 328, and all affected Embraer airplanes are 

equipped with either a certificated primary or advisory ice detection systems (IDS); hence, these 

airplanes are in compliance with either §121.321(a)(1) or §121.321(a)(2) and this final rule will

impose no costs on the operators of these airplanes. 
15

We note all affected part 121 turbojet airplanes are already in compliance and hence will

incur no costs from this final rule.

The FAA used the FAA Statistical and Forecast Branch7for the part 121 regional 

turboprop forecast to estimate the number of active and retired turboprop airplanes over the 

analysis interval. Since the FAA Statistical and Forecast Branch does not forecast turboprop 

airplanes by equipment type, for the costs estimate, we retire the older active airplanes affected 

by the final rule first. 

When we estimated the costs for the NPRM we used the 2008 FAA fleet forecast. The 

2008 FAA fleet forecast had an aggressive turboprop retirement forecast. For the final rule, we 

used the 2010 FAA Fleet Forecast. Over the analysis interval, the 2010 FAA retirement forecast 

is flat for turboprops as opposed to the decline in the 2008 FAA fleet forecast. The impact of the 

flat 2010 retirement forecast is that more turboprops will be active over the analysis interval. 

More active turboprops raises the costs of the final rule relative to the NPRM. Based on this 

approach, the C-46, CV-340/440, DHC-6, and SA-227, and SD-3-60 airplanes will be retired 

before the 2013 effective date of this final rule and hence incur no compliance costs.

The remaining affected airplanes are the B-1900 and Saab 340. Since these airplanes do 

not have an IDS; they will have to comply with §121.321(a)(1), (a)(2) or (a)(3) and incur the 

costs of either installing a primary or advisory IDS or continuously operating their IPS when 

operating in conditions conducive to icing. 

Using the costs discussed above and listed in Appendix C1, C2, and C3, we estimate the 

total nominal cost of making the B-1900 and Saab 340 compliant to this final rule. 

We estimated the costs for §§121.321(a)(1) and (a)(2) by adding the system design, 

qualification, certification and retrofit costs to the operator cost. We calculated the operator cost 
16

by taking the product of the number of active affected part 121 turboprop airplanes and the 

operator cost. 

We estimated the cost for §121.321(a)(3), by first adding the non-recurring costs for the 

B-1900, which was not subject to the ADs, to the non-recurring costs for the Saab 340, which 

was subject to the ADs. Since we estimate the final rule will not be promulgated until 2011, and 

has an effective date 24 months from the promulgation of the final rule, the non-recurring costs, 

for updated AFMs and flight testing will occur two years after the final rule is published. From 

year one through 20 of the analysis interval, the recurring costs extend to operators of active B1900 and Saab 340 turboprop airplanes. These recurring costs will decline over the analysis 

interval because of Saab 340 and B-1900 airplanes retiring. Table 4 shows the details of the 

estimated nominal, three and seven percent present value costs for each section of the final rule.

 

7APO-110 - FAA Aerospace Forecast, 2010-2030, Table 26
17

III.10 Summary of Costs

Based on the IPHWG airplane compliance costs, the FAA estimates the costs for 

§121.321(a)(1)-(3) will range between $11.8 million to $18.4 million on a nominal basis. The 

nominal value lowest cost option is $11.8 million for §121.321(a)(2), which requires operators to 

install an advisory ice detection system and employ visual cues of the first sign of ice formation. 

Although the nominal value lowest cost option is §121.321(a)(2), the FAA believes that 

operators will choose §121.321(a)(3) because this option does not require large up-front direct 

costs of designing and certificating an advisory ice detection system for turboprops that will be 

over 20 years old by the effective date of this final rule. In addition, our cost estimate of $12.7 
18

million for §121.321(a)(3) is for using deicing boots 12 months a year, which is an over-estimate

because ice protection systems, such as deicing boots, are not used year round. Lastly, on a 

present value basis, §121.321(a)(3) is the low cost option. Therefore, we believe that 

§121.321(a)(3) will be the preferred option to comply with this final rule.

The seven percent present value cost for §121.321(a)(3) of this final rule over the 

analysis period is about $6.7 million. The three percent present value cost of this final rule over 

the analysis period is about $9.4 million. We estimate that the final rule’s non-recurring costs of

certificating affected airplanes for the low cost option §121.321(a)(3) are approximately

$400,000 and about $12.3 million for recurring operator costs and to provide training for pilots 

and copilots of airplanes involved with new procedures mandated by the final rule. Appendix C4

shows the details of the certification and operator costs, for each section, throughout the analysis 

period.
19

IV. THE BENEFITS ESTIMATE

The FAA expects the final rule to generate potential safety benefits of about $36.6

million over the 20-year analysis interval, about $18.9 million at the seven percent present value

rate, and about $27.1 million at the three percent present value rate. These total benefits must be 

factored down, for certain airplanes, because of existing Airworthiness Directives (ADs). The

industry Ice Protection Working Group (IPHWG) and the FAA assigned a 50 percent 

effectiveness rate for the final rule given existing ADs. Based on industry’s judgment, and we 

received no comments on this value for the NPRM, we continue to use 50%.

Under the current operating rules, it is the responsibility of the flight crew to decide 

whether icing conditions have been encountered. Neither the operation regulations nor the 

certification regulations require a means for the pilot in command to identify that hazardous icing 

conditions have been encountered. An examination of the accident and incident history revealed 

that the flight crews must be provided with a clear means to know when to activate the Ice 

Protection System (IPS). This final rule will ensure timely activation of the IPS. 

Since 1993, 14 CFR Part 121 passenger-carrying air operators have had at least one

accident which may have been prevented if this rule had been in effect. The accident occurred in 

1993 in Hibbing, MN. The airplane was a Jetstream BA-3100 and while on approach collided 

with trees and terrain resulting in 18 fatalities, no injuries, and a destroyed airplane.8 This

accident occurred in a small (under 60,000 pound MTOW) 14 CFR Part 121 airplane, which is 

affected by this final rule. 

 

8 National Transportation Safety Board (NTSB) Accident Reports, FAA National Aviation Safety Data Analysis 

Center (NASDAC).
20

In addition to this U.S. accident, there were 10 international icing related accidents that 

could have been prevented if this final rule was in effect internationally. However, we assign no 

quantitative benefits to these icing-related accidents. Table 5 shows these international icingrelated accidents.

Additional icing related accidents during the cruise, holding and landing phase of flight 

have also occurred in Greenland, Italy, Kazakhstan, Russia, and Sweden.9

We also found accidents and incidents that occurred under Part 135 operations. They are 

considered as relevant to this final part 121 rule because under today’s regulations those Part 135 

operations would be classified as Part 121.

Now we discuss the component benefit of an averted accident which forms the 

quantitative basis for future benefits. 

The benefit of avoiding an accident includes averted fatalities, injuries, aircraft 

replacement or repair, and accident investigation costs. In estimating benefit values, the FAA 

uses $6.0 million for an avoided fatality, $521,000 for a serious injury (assumed to be the 

average of a severe, serious, and moderate injury), and $12,000 for a minor injury. The 

 

9

Ice Protection Harmonization Working Group (IPHWG) of the Aviation Rulemaking Advisory Committee 

(ARAC).
21

additional associated medical and legal costs for a fatality are $265,400, for a serious injury

(assumed to be the average of a severe, serious, and moderate injury) $93,267, and for a minor 

injury $5,000. The air carrier accident investigation cost for the NTSB is $1,931,800 and for an 

FAA accident investigation $681,700. The NTSB accident investigation reports provided the 

number of fatalities and injuries. The FAA estimates the average value of avoiding an icingrelated accident, where the airplane is destroyed, to be about $119.9 million.10

 

We believe this final rule could have prevented at least one historical accident and the 18

fatalities that occurred. Further, we expect future accidents in conditions conducive to icing to 

also occur. Herein, the methodology is presented to substantiate the basis for increasing the 

value of preventing icing related accidents that could occur over the analysis interval in the 

absence of the final rule:

1. Based on the casualty losses from the 1993 Hibbing, MN Jetstream BA-3100 accident, 

we calculate three separate accident and casualty rates. These accident and casualty rates 

were calculated by dividing the total losses per category (fatality, investigation and accident) 

over the 1993 through 2010 period by the average number of part 121 air carrier airplanes

operating in the time period.11 The results of this derivation are exhibited in Table 7.

 

10Economic Values For FAA Investment and Regulatory Decisions, A Guide

11 U.S. Department of Transportation, Federal Aviation Administration, Office of Aviation Policy, Plans and 

Management Analysis, Statistical and Forecast Branch.
22

2. The historical accident and casualty rates, calculated in step 1 were multiplied by the 

annual number of projected declining part 121 affected U.S. operated airplanes from 2011

through 2032.

12

3. After totaling the estimated number of future accidents and casualties over the analysis

period, we used the values in Table 6 to determine the total potential benefits of the final

rule.

Table 7 shows these calculations. Appendix B1 shows the details of the benefit costs 

throughout the analysis period.

 

12 ibid
23

In the absence of the final rule, based on past accident rates, we expect approximately

one accident will occur over the analysis period. This accident is expected to result in 

approximately five fatalities. 

The accident-rate assumptions must account for the effects of recent ADs against affected 

models because the FAA does not accept that this icing rule, by itself, will prevent all future 

accidents. The ADs were issued to establish an increased level of safety with respect to initiating 

activation of the IPS and providing cues to determine when large droplet icing conditions have 

been encountered. The benefits analysis considers accidents and incidents that occurred prior to 

the issuance of the ADs. 

In 1996, ADs were issued for airplanes with unpowered controls and pneumatic de-icing 

boots. In 1999 a second series of ADs were issued for airplanes with pneumatic de-icing boots 

to activate the systems at the first sign of ice accretion. These two ADs accomplish much of the 

same objectives as this 14 CFR Part 121 final rule. 

A second set of ADs required the activation of the IPS at the first sign of ice accretion 

anywhere on the airplane or upon annunciation of an ice detection system. The system is to be 

operated on automatic mode if available or by manually cycling to minimize ice accretions on 

the airframe. This directive accomplishes much of what final rule sections (a) and (b) are

proposed to achieve. The main difference is that the final rule will require a more conservative 

activation cue (temperature and visible moisture) and that the visual cues used in combination 

with an advisory ice detection will require validation (or re-validation).

Due to the similarity of requirements, we realize that the ADs have accomplished a 

substantial portion of the safety increase attributed to the final rule within the benefits analysis. 

The IPHWG, with FAA concurrence, believes it is reasonable to assume that the ADs have 
24

already accomplished 50 percent of the safety benefit attributed to the final rule in the analysis. 

This difference would indicate that the actual safety benefit of the final rule is on the order of 50 

percent of the present values due to the effectiveness of the ADs. 

For the two affected airplanes, the ADs apply to the Saab 340 and not the B-1900. 

Therefore the benefits of preventing future accidents on Saab 340 airplanes have been reduced 

by 50 percent.

Table 7 shows the benefits of preventing this accident and these casualties are estimated 

at $36.6 million in nominal dollars. We proportioned the total and present value benefits from 

Table 7 by calculating the percentage of Saab 340 and B-1900 airplanes operating in 2010. We 

then added 100 percent of the B-1900 portion of the total and present value benefits to 50 percent 

of the Saab 340 portion to account for the safety benefits from the ADs. Assuming that the 

actual safety benefits of the final rule is on the order of 50 percent for the Saab 340 and 100 

percent for the B-1900, benefits of preventing this accident and these casualties are estimated at 

about $27.2 million in nominal dollars. Table 8 shows these adjusted benefits, including the 

ADs effective ratio for the Saab 340. 

V. BENEFIT-COST SUMMARY

In the absence of this final rule, it is highly likely that future icing-related accidents will

occur. This study expects at least one accident and five fatalities over the 20-year analysis 

interval could be prevented by the enactment of this final rule and ADs. The benefit of the final
25

rule will be avoiding this anticipated accident. We accounted for the effects of recent ADs

against affected models. The benefits of the final rule are estimated to be $22.1 million in 

nominal dollars over the analysis period. 

It is estimated that over the analysis period, cost of the final rule is about $12.7 million in 

nominal dollars. This includes the cost of ice detection systems design, qualification, 

certification, crew training, equipment purchase and installation, and testing. 

Table 9 shows these results.

The estimated $22.1 million benefit of this final rule exceeds the estimated $12.7 million 

cost in nominal dollars. We note that for the total and three percent present value cases, the 

estimated benefits also exceed the estimated costs. Thus, accepting the IPHWG’s 

recommendations, the FAA concludes that the benefits of the final rule do justify the costs of this

14 CFR Part 121 final rule.
Appendix C1

Manufacturer Non-recurring and Direct Operator Costs for Section (a)(1)
27

Appendix C2

Manufacturer Non-recurring and Direct Operator Costs for Section (a)(2)
28

Appendix C3

Manufacturer Non-recurring and Direct Operator Costs for Section (a)(3)
29

Appendix C4

Cost Summary
30

Appendix B1

Benefit Summary