AFS-15-079-E

Exemption No. 14074

UNITED STATES OF AMERICA

DEPARTMENT OF TRANSPORTATION

FEDERAL AVIATION ADMINISTRATION

WASHINGTON, DC 20591

In the matter of the petition of

TATONDUK OUTFITTERS, LTD. 

d.b.a. EVERTS AIR CARGO Regulatory Docket No. FAA-2014-0087

for an exemption from § 121.321

of Title 14, Code of

Federal Regulations

GRANT OF EXEMPTION

By letter dated February 3, 2014, Mr. Robert W. Everts, President, Tatonduk Outfitters, Ltd. 

d.b.a. Everts Air Cargo, 5525 Airport Industrial Road, Fairbanks, Alaska 99709, petitioned the 

Federal Aviation Administration (FAA) on behalf of Tatonduk Outfitters, Ltd. d.b.a. Everts 

Air Cargo (EAC) for an exemption from § 121.321 of Title 14, Code of Federal Regulations 

(14 CFR). The proposed exemption, if granted, would allow EAC to operate the C-46 airplane 

identified on its operations specifications (N54514) in icing conditions within the state of 

Alaska.

The petitioner requests relief from the following regulation:

The petitioner requests relief from § 121.321 which applies to airplanes with a 

certificated maximum takeoff weight of less than 60,000 pounds used in part 121 

operations. Those airplanes may not be operated in conditions that are conducive to 

airframe icing unless equipped with a certificated primary airframe ice detection system

which is activated automatically or manually, when activation is necessary

(§ 121.321(a)(1)), or the airframe ice protection system would be activated when an 

advisory airframe ice detection system or visual cues (whichever occurs first) indicate it 

is necessary (§ 121.321(a)(2)).
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Alternatively, § 121.321(a)(3) allows airplanes that are not equipped in accordance with 

§ 121.321(a)(1) or (2) to operate in icing conditions if the airframe ice protection 

system is activated prior to and is operated during specific phases of flight which 

include:

(1) Takeoff climb after second segment;

(2) Enroute climb;

(3) Go-around climb;

(4) Holding;

(5) Maneuvering for approach and landing; and

(6) Any operation at approach or holding airspeeds.

Section 121.321(a)(3) also requires the airframe ice protection system to be activated 

and operated during any other phase of flight at the first sign of ice formation 

anywhere on the airplane, unless the Airplane Flight Manual (AFM) specifies that it 

should not be used or provides other operational instructions.

The remaining requirements in § 121.321 identify procedures required for operating 

the airframe ice protection system (§ 121.321(c) and (d)) and approvals for 

installations of airframe ice detection systems (§ 121.321(e)).

The petitioner supports its request with the following information:

The petitioner uses a C-46 airplane to conduct all-cargo, supplemental, operations 

within Alaska and states that its C-46 was type-certificated in 1940 under the 

provisions of Civil Air Regulation (CAR) 3A2. The petitioner contends that, because 

the C-46 is an older aircraft with limited commercial usage, there is little likelihood of

the successful development, certification, and production of either a primary airframe 

detection system or an advisory airframe detection system for this aircraft within a 

foreseeable timeframe or within practical economic constraints. As such, the C-46 

cannot comply with either §§ 121.321(a)(1) or (a)(2). Further, the petitioner asserts 

that were it to operate the C-46 in accordance with § 121.321(a)(3), that operation 

would be contrary to the Everts Air Cargo Operating Manual which specifically 

prohibits continuous de-icing while in flight, and contrary to § 121.321(a)(3)(ii), which 

restricts operations contrary to the AFM. 

As the petitioner’s C-46 cannot currently comply with all of the de-icing requirements

in § 121.321, the petitioner has been instructed by the Denali Certificate Management 

Office to terminate all part 121 operations in its C-46 during known icing conditions. 

The petitioner states that, under the circumstances, it is effectively prevented from 

conducting C-46 operations in Alaska during the winter months. As a result, the 

petitioner states it has experienced commercial harm and has had to restrict service to 

isolated Alaskan communities that require necessities for sustenance and survival 

during the winter months. 
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The petitioner asserts that its operation of its C-46 aircraft is consistent with the 

approved flight manual and that its procedures will assure the highest level of safety 

for its C-46 operations in icing conditions, providing for the safe operation of this

aircraft type. The petitioner highlights that it has effectively operated in extreme icing 

conditions for over 17 years without any incident or accident related to, or caused by, 

icing. The petitioner further states,

The following procedure[s] for C-46 operations provides not only a level of 

safety equivalent to that provided by any of the three options permitted under 

§ 121.321, but also the only means of compliance available to the petitioner

under the circumstances.

1. The aircraft shall be determined to be free of ice and upper wing frost 

accumulation prior to flight.

2. The crew shall be vigilant for the accretion of ice, paying particular attention 

to the unheated cockpit windshield structure.

3. During operations in conditions conducive to airframe icing, the flight crew 

shall follow the guidance provided in § 121.321(d)(3) [sic].

4. This deviation is limited to operations conducted within Alaska and is

consistent with the Approved Operating Manual for this aircraft.

See Petition for Exemption at p. 3. 

The petitioner states that it has used C-46 aircraft as the mainstay of its non-scheduled 

cargo operations into remote areas of Alaska during the winter months. The petitioner 

contends that the lift capacity, durability, and functionality of the C-46, in restricted 

runway and weather conditions, make it a reliable, economic choice in these extreme 

conditions. Further, the petitioner points out that there is currently no ice alert system 

available for the C-46 and that there is no incentive for any aircraft manufacturer to 

create such a system because EAC conducts the only commercial operations using the 

C-46. Based upon these factors, the petitioner argues that the relief sought is narrowly 

tailored to address the effects of § 121.321 on C-46 operations without degrading

part 121 safety standards.

The petitioner also contends that older aircraft, such as the C-46, were not thoroughly 

considered by FAA in the § 121.321 rulemaking and as such have been inadvertently 

included in a regulation for which there is no means of compliance. In support of this 

position, the petitioner first explained that the Activation of Ice Protection notice of 

proposed rulemaking (NPRM) (74 FR 61055 (November 23, 2009)) incorrectly

asserted that, after review of ice detector technology, the FAA and Ice Protection 

Harmonization Working Group (IPHWG) found that viable means of compliance with 

the NPRM existed. The petitioner contends that while this may be true for aircraft 
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certificated under parts 23 or 25, it does not apply to certain older aircraft such as the 

C-46. Therefore, by not addressing the capability for all aircraft to comply with this 

rule, the petitioner feels that the FAA has grounded those aircraft for which there is no 

viable means of compliance, such as the C-46, for operations in icing conditions.

Additionally, the petitioner states that Advisory Circular (AC) 121.321-1, published 

nearly concurrently with the Activation of Ice Protection final rule (76 FR 55241

(August 22, 2011)) addresses a means of compliance applicable only to parts 23 and 

25 aircraft with a maximum certificated take-off weight less than 60,000 pounds. The 

petitioner contends that this AC indicates that older aircraft, such as the C-46, were 

included under a regulation meant only for those more modern aircraft which had a 

viable means of compliance. The petitioner attributes this oversight to the fact that

currently, a very limited number of CAR 3A2 certificated aircraft conduct commercial 

operations. Further, the petitioner asserts that by way of AC 121.321-1, FAA 

interprets § 121.321 as not applying to vintage aircraft, such as the petitioner's C-46. 

The petitioner argues that the relief sought by this exemption would be consistent with 

this interpretation.

The petitioner concludes that, based upon the apparent inadvertent inclusion of C-46 

aircraft in § 121.321, the only meaningful remedies would be to either amend the rule 

to exclude the C-46 and other similar aircraft, or provide this requested exemption 

relief. The petitioner contends that due to the pressing need for the C-46 services in 

Alaska which are provided by the petitioner during the winter months, the most 

efficient and expeditious remedy would be to grant this petition on an expedited basis.

The petitioner points out that by the preamble to the final rule adding § 121.321, it

provides the following explanation for the FAA’s decision to exclude operations 

conducted under parts 91 and 135 from the activation of airframe ice protection 

systems requirements:

We considered including parts 91 and 135 operations during 

deliberations of the IPHWG and during drafting of the NPRM. We 

determined, however, that the increased flexibility afforded by

unscheduled operations (the types of operations governed by part 

91 and part 135), coupled with appropriate direction on when pilots 

could activate ice protection systems (usually at the first sign of 

icing or in conditions of visible moisture and specific 

temperatures) provides an adequate level of safety for ice 

protection system activation. Pilots flying scheduled operations, 
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on the other hand, may not have the flexibility to avoid flying into 

weather that would otherwise be avoided.1

See Petition for Exemption at p. 4.

The petitioner suggests that this preamble language demonstrates the FAA determined 

that, for non-scheduled operations, the operational environment would allow flexibility 

in scheduling to preclude flights into icing, and that so long as the pilots administered 

de-icing procedures consistent with the aircraft flight manual, the flight crew could

detect and prevent a hazardous accumulation of ice in a manner not requiring the 

additional safeguards of § 121.321. The petitioner further suggests that inclusion of 

supplemental operations under § 121.321 is inconsistent with the stated purpose of 

§ 121.321 and creates a regulatory scheme which is inherently arbitrary. The 

petitioner argues that if there is no safety-related reason to apply the requirements of

§ 121.321 to part 91 and part 135 non-scheduled operations, then, it necessarily 

follows that, part 121 non-scheduled operations should be treated in the same manner 

and excluded from § 121.321.

The petitioner argues that this point is particularly relevant to its request for relief 

since it utilizes its C-46 aircraft only for supplemental intrastate flights. The petitioner 

highlights that it does not use its aircraft to perform scheduled operations. The 

petitioner asserts that, from an operational standpoint, its operations are identical to the 

type of operations which FAA addressed in the quoted preamble language and the 

same argument for excluding such operations from § 121.321 apply equally to the 

petitioner as they do to parts 91 and 135 operations.

A summary of the petition was published in the Federal Register on November 3, 2014, 

(79 FR 65294). No comments were received.

The FAA's analysis is as follows:

The FAA has fully considered the petitioner’s request and supporting information in 

the petition for an exemption from § 121.321 for operations conducted by EAC with 

C-46 aircraft. In analyzing a petition for exemption the FAA carefully considered

whether granting the petition would be in the public interest and whether it would 

adversely affect safety.

On August 22, 2011, the FAA published the “Activation of Ice Protection” final rule, 

which created § 121.321 (76 FR 52241). The FAA implemented this rule to increase 

the standard of safety as a result of accidents and incidents in which the flight crew did 

 1 76 FR 55241, 52244 (August 22, 2011).
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not start the airframe ice protection system soon enough. This rule is meant to prevent 

that from happening by giving flight crews a clear means of knowing when to activate 

the airframe ice protection system. For certain airplanes certificated for flight in icing, 

§ 121.321 requires either installation of ice detection equipment and procedures for its 

use, or changes to the AFM to ensure timely activation of the airframe ice protection 

system.

The C-46 identified on the petitioner’s operations specifications and operated by the 

petitioner is not equipped with a certificated primary airframe ice detection system. 

Section 121.321(a)(3) allows airplanes that are not equipped in accordance with 

§ 121.321(a)(1) or (2) to operate in icing conditions if the airframe ice protection 

system is activated prior to and is operated during specific phases of flight and at the 

first sign of ice formation anywhere on the airplane, unless the AFM specifies that it 

should not be used or provides other operational instructions. The petitioner has 

expressed concern that operating the C-46 ice protection system in the manner 

required by § 121.321(a)(3) would be contrary to the C-46 flight manual, which the 

petitioner says prohibits continuous de-icing during flight. 

The FAA finds that the procedures used by the petitioner’s pilots to detect icing 

conditions and activate the ice protection system on its C-46 aircraft support a finding 

that safety will not be adversely affected by granting the petitioner an exemption from 

§ 121.321 subject to the conditions and limitations identified below. The C-46 design 

attributes and procedures in the C-46 manual enable pilots of this aircraft to see and 

evaluate airframe and wing contaminants in a timely manner, which contributes to the 

pilots’ awareness of the need for ice protection system activation. The petitioner’s C46 crews detect airframe ice accumulation by observing ice formation on the 

windshield, windshield wipers and wiper alcohol tube which have been found to be 

representative of airframe ice formation. Further, the agency has determined that wing 

ice lights are installed on the Tatonduk C-46 and, unlike modern swept-wing airplanes,

the illuminated aircraft wings are visible from the flight deck. These factors allow the 

crew to identify wing contaminants. As a result, the FAA notes that, for the purposes 

of this exemption, wing ice lights must remain installed and operable or the airplane 

must be restricted to daytime-only flight when conditions conducive to icing exist.

With regard to activation of the ice protection system, the C-46 Operations Manual 

includes the following procedure that states, “Allow ice to build up to about 1/4 inch 

thickness then operate the deicers to break it off. Once the surfaces are cleared of ice,

turn the deicer off, and let the ice form again. Do not allow an excessive accumulation 

as the deicers may be unable to clear the ice.” However, Information for Operators 

(InFO) 09007 (May 5, 2009) explained that pilots had been taught to wait until a 

recommended thickness of ice builds up (typically 1/4”-1/2”) before activating the 

deicing boots because early activation of the boots was thought to result in ice bridging

and thus rendered the boots ineffective. Further ice protection system tests found that
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modern boots (i.e. typical of aircraft certified after 1960 whose boot tubes diameter are

less than 1 3/4” and operating pressures are 15 pounds per square inch gauge (psig) or 

greater and whose boots have fast inflation/deflation rates) should be activated 

whenever the aircraft is in ice-conducive conditions. In addition, modern deicing boot 

systems automatically cycle the deicing boots to decrease the workload. For systems 

that do not cycle automatically, pilots were instructed to cycle the boots as necessary. 

The FAA finds that, although the deice boots on Tatonduk’s C-46 were last replaced in 

2003, they are not considered to be of modern design since they were manufactured to 

original specifications from blueprints under which the aircraft was type certificated in 

1940. Tatonduk’s C-46 deice boots are 2 9/16 inches and 2 11/16 inches diameter, use 

8 psig and an inflation/deflation rate of more than 11 seconds. Since they are not

considered a modern design, as described in the previous paragraph, any enhancement 

in safety afforded by activating the boots prior to the accumulation of 1/4 inch of ice 

has not been documented. 

The FAA agrees with the petitioner that the lift capacity, durability, and functionality

of the C-46 in restricted runway and weather conditions make it uniquely suited as a 

reliable, economic choice for delivering cargo to remote locations in Alaska’s extreme 

conditions. While most modern transport aircraft tricycle landing gear preclude them 

from landing under the conditions which exist at these remote locations, the C-46’s 

uniquely large main-mounted tires and landing gear configuration make it ideally 

suited for such operations. Additionally, the petitioner has operated this aircraft since 

1995 in the harsh winter environment in Alaska using these procedures to detect 

airframe and wing contamination on its C-46 aircraft, devoid of any ice-related 

incidents or accidents.

The FAA finds that a grant of exemption in this specific case would be in the public 

interest because of the unique capabilities of the airplane to operate to remote Alaskan 

communities subject to the conditions presented by Alaska’s weather and the short 

gravel runways at the airports in the communities the petitioner serves. The petitioner 

states that remote Alaskan communities rely upon deliveries which include food and 

medical supplies necessary for their sustenance. The agency agrees that in many cases 

remote Alaskan communities not serviced by roads rely exclusively on aircraft for the 

delivery of the essential supplies described above. 

The agency recognizes that the prospect of the development of an airframe ice 

detection system is unlikely given the extremely limited and specialized use of this 

aircraft in Alaska.

Accordingly, the FAA finds that unless the agency grants an exemption from 

§ 121.321 for operations conducted by the petitioner with its C-46, the aircraft would 

effectively be disallowed for use during winter operations in Alaska which could have 
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a substantial impact on the health and welfare of the communities it serves. Therefore, 

the FAA finds a grant of relief to be in the public interest.

In response to the petitioner’s arguments that the Activation of Ice Protection final rule 

should have treated supplemental operations in the same manner as parts 91 and 135 

on-demand operations, the agency disagrees with the assertion that all non-scheduled 

operations are comparable. Supplemental operations are conducted under the rules of 

part 121, and are thus held to the highest level of safety. Finally, the petitioner 

emphasizes the fact that it uses its C-46 aircraft only in part 121 non-scheduled, allcargo supplemental operations. Although the type of operation (i.e. supplemental) is 

not determinative for purposes of this exemption, the FAA agrees that the petitioner 

does have greater flexibility in scheduling its flights that could reduce the pressure to 

operate when there are forecast severe icing conditions.

Advisory Circular (AC) 121.321-1 does not serve as a basis for this exemption but in 

this instance the intent of the AC is to facilitate compliance. Paragraph 2 of that AC 

states: “This material is neither mandatory nor regulatory in nature and does not 

constitute a regulation. It describes acceptable means, but not the only means, for 

demonstrating compliance with the applicable regulations.” The agency is not 

persuaded by an argument that omission of certain guidance material is indicative of 

the intended applicability of the rule, particularly when the rule is clear on its face.

The FAA’s Decision:

In consideration of the foregoing, I find that a grant of exemption is in the public 

interest. Therefore, pursuant to the authority contained in 49 U.S.C §§ 106(f), 40113,

and 44701, delegated to me by the Administrator, Tatonduk Outfitters, Ltd. d.b.a.

Everts Air Cargo is granted an exemption from § 121.321 to the extent necessary to

allow EAC to operate N54514, a C-46 airplane, in icing conditions within the state of 

Alaska, subject to the conditions and limitations listed below.

Conditions and Limitations:

1. This exemption applies only to the Curtiss Wright FLYTGR-C-46-D airplane with 

registration number N54514 and serial number 33285 and identified on EAC 

operations specifications. 

2. This exemption applies only to the airplane identified in Condition and Limitation 

No. 1 when it is equipped with wing deice boots manufactured to the aircraft’s 

original type-certificated specifications and only when it is operated by EAC in allcargo operations within the state of Alaska.
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3. Prior to serving as a pilot in operations described in Condition and Limitation 

No. 2, each must complete annual EAC cold weather training which addresses 

critical surfaces ice detection, proper use of ice protection and the effect of ice on 

C-46 aircraft performance. 

4. EAC pilots serving in operations described in Condition and Limitation No. 1 or 

preparing the airplane for a flight in an operation described in Condition and 

Limitation No. 1 must adhere to applicable cold weather policies and procedures as 

delineated in the EAC C-46 Operating Manual, and the Curtiss Wright C-46 

Airplane Flight Manual.

5. EAC is prohibited from operating into known or forecast severe icing conditions

when conducting operations under this exemption.

6. Wing lighting, appropriate for ice detection, must be operable if this aircraft is 

used during nighttime operation in meteorological conditions conducive to icing. 

This exemption terminates on December 31, 2017 unless sooner superseded or rescinded.

Issued in Washington, DC, on

/s/

Jodi L. Baker

Acting Deputy Director, Flight Standards Service