AFS

- 15

- 2430

- E Exemption No. 13337

UNITED STATES OF AMERICA
DEPARTMENT OF TRANSPORTATION
FEDERAL AVIATION ADMINISTRATION WASHINGTON, DC 20591

In the matter of the petition of

SOUTH WEST AIRLINES R egulatory Docket No. FAA

- 201 5

- 2368
CORPORATION

for an exemption from § 121. 629 ( b ) of Title 14, Code of Federal Regulations

GRANT OF EXEMPTION

By letter dated June 5 , 201 5

, Mr. Alan Kasher, Managing Director /Director of O perations, Regulatory Programs and Compliance, Southwest Airlines Corporation, 2702 Love Field Drive, P.O. Box 36611, TOP

- 1DO , Dallas, TX 75323 5, petitioned the Federal Aviation Administration (FAA) on behalf of Southwest Airlines for an exemption from § 121. 629 ( b ) of
Title 14, Code of Federal Regulations (14 CFR). The proposed exemption, if granted, would
exempt Southwest Airlines from the requ irement that “n o person may take off an aircraft when frost, ice, or snow is adhering to the wings,” if Boeing, the o riginal e quipment

m anufacturer (OEM) of the B

- 737

- 700,

- 800 Next Generation ( NG ) airplanes, has determined
a safe zone within which cold so aked fuel frost (CSFF) is permissible ; visibly mar k ed the zone on the wing ; and placed an appropriate limitation in the FAA

- approved Airplane Flight Manual (AFM).

The petitioner requests relief from the following regulation:

Section 121.6 29 ( b ) states th at n o person may take off an aircraft when frost, ice, or snow is adhering to the wings, control surfaces, propellers, engine inlets, or other critical surfaces of the aircraft or when the takeoff would not be in compliance with paragraph (c) of this secti on. Takeoffs with frost under the wing in the area of the fuel tanks may be authorized by the
Administrator.2

The petitioner supports its request with the following information:

The petioner supports its request by explaining how CSFF is formed. In gener al, airframe icing is known to be a hazard to the safe operation of aircraft, especially on the wing and other parts of an aircraft that exist to produce lift

. Hence, the regulation, § 121.629(b), which states
that wings, control surfaces, propellers, en gine inlets, or other critical surfaces must be clean from forst, ice or snow, is a mitigation for this known hazard. In the case of CSFF, w ing surface texture changes can disrupt laminar airflow on the wing causing degradation of lift
and increased stall speed, adversely affecting aircraft performance. Ice on the wing may form in a particular set of conditions that may include near or sub

- freezing temperatures in combination with precipitation and/or high humidity (especially fog). Additionally, frost m ay form in clear

, meteorological conditions on wing areas with underlying cold soaked fuel caused by cruise at high altitude followed by landing in a humid climate, which is a condition
known as CSFF.

The petitioner states that t he relief requested by S outhwest Airlines is precedented by engineering and aerodynamic analysis performed in conjunction with the National Aeronautics and Aerospace Administration (NASA) and by Boeing

, the OEM for the

B737

- 700 and

- 800 NG series aircraft

. This CSFF analysis determined th at lift impairment is negligible , given the controlling factor s set

- forth by the OEM ’s miscellaneous limitations and

FAA

- approved AF M

. Given these results, the expense and environmental impact of applying
de

- ic ing fluid in the CSFF condition is not warr a nted

. The petitioner states the relief requested presents no decrease in safety and is in the interest of the flying public. The petitioner explain s that the appro priate procedures and l imitation s will be documented in the FAA approved Boein g B

- 737

- 700,

- 800 NG AFM

. T he relief requested is limited to those
aircraft for which the analysis was performed by Boeing and approved by t he FAA. ( This analysis includes the ER model as specified by Boeing

. )

The petitioner states that Boeing has applie d painted lines defining an area on the upper surface of the wings on certain B737NG /ER aircraft, where with certain other limitations

, CSFF may exist with negligible impairment of performance. The petitioner states that all
Southwest B737

- 700 and

- 800 NG series aircraft have the lines defining the permissible area of CSFF painted on the upper wing surfaces. The petitioner states that Boeing has issued specific “Miscellaneous Limitations” regarding CSFF in its FAA

- approved AFM that set forth
conditions un der which takeoff is not permitted. The extracted Boeing

- developed CSFF
miscellaneous limitations are as follows :

MISCELLANEOUS LIMITATIONS

COLD SOAKED FUEL FROST (CSFF)

Takeoff with cold soaked fuel frost on the wing tank upper surfaces is not permit ted if any of the following conditions are present:3

1. The ambie nt air temperature is below +4 degree celsius ( C ) , +39 degree fahrenheit ( F )

.

2. The tank fuel temperature is below

- 16 degree C, +3 degree F.

3. There is cold soaked fuel frost on the wing tank upp er surfaces that is beyond the lines defining the permissible cold soaked fuel frost area.

4. There is precipitation or visible moisture (rain, snow, drizzle, or fog with less than 1 mile visibility).

Based on the data and analysis presented by Boeing

, the petitioner has concluded that if the
above listed limiting conditions are not present

, operations with CSFF on the wing tank upper
surfaces may be safely conducted.

The petitioner states that FAA approval of the amended AFM and the Southwest Airli nes training program provide the basis upon which operation s with CSFF is permissible and should be allowed pursuant to § 1 21.629(b) which provides that “t akeoffs with frost under the wing in the area of the fuel tanks may be authorized by the Administrato r.”

The petitioner states that the amended AFM limitation and training program in conjunction with Boeing’s technical data analysis and procedures assures that operations are only permitted in certain instances of CSFF

. The petition highlights that o pera tions not specifically covered within the Boeing procedures, FAA

- approved AFM

, and training

program would not be authorized by this exemption and § 121.629(b) would appl y

.

A summary of the petition was published in the Federal Register on April 29, 2015, 80 FR
23848. 1 Six sets of public comments were submitted to the docket. Representatives of the airline industry, including Airlines for American, Delta Air Lines, Southwest Airlines, United Airlines, and Alaska Airlines, supported a grant of exemption on the basis that the conditions tests by Boeing and included in the FAA

- approved AFM demonstrate that safety of flight would not be negatively affected. The Air Line Pilots Association supported a grant of exemption but emphasized that the Captain retains the authority to make the final decision on operating in CSFF conditions.

The FAA's analysis is as follows:

The purpose of § 121.629(b) is to ensure the safest possible operation in the presence of ice,
frost and snow . T herefore, the regulations require a clean wing but state that take

- offs with frost under the wing in the area of the fuel tanks may be authorized by the Administrator.

1 The FAA requested public comment on this proposal in response to Airlines for America’s petition for exemption from § 121.629(b), Docket No. FAA

- 2015

- 0555. That petition was withdrawn by the petitioner
before FAA action.4

Althoug h this petition for exemption is requested by Southwest Airlines, the aircraft
manufacturer

, Boeing, provided the FAA with the associated conditions and limitations for operations with CSFF. Boeing approached the FAA in 2003 providing data and performance analysis which it believed established the basis for a grant of exemption from the requirements of § 121.629(b). The FAA allowed industry to apply the Boeing procedure for a trial period of 6 months. While no incidents related to the existence of CSFF occurred during this period, the FAA, as an operations policy decision, did not extend the approval.

In 2011, Boein g approached the FAA requesting reconsideration. The FAA formed a team to study the Boeing proposal. Led by the subject matter expert on airplane icing

, the team consisted of the Chief Scientific Technical Advisor for Icing for the FAA, the Chief Aircraft Aerodynamcist for NASA, the Head of Aircraft Icing Research at the FAA Technical Center,
and the Chief Ground De

- icing Scientist for the FAA Techni c al Center. After a three

- year study and in

- depth analysis to validate the Boeing presentation, including c onsultation with Transport Canada (which had previously granted this type of exemption), the team recommended acceptance of the Boeing proposal.

After careful review, FAA Aircraft Certfication (AIR) in coordination with Flight Standards (AFS) validated the data, procedures, and limitations set forth within the Boeing 737

- 700,

- 800, and ER performance analysis of CSFF. The CSFF analysis determined that lift impairment is negligible, given the controlling factors set

- forth by the OEM’s miscellaneous
limitati ons and FAA

- approved AFM.

The FAA also determined there would be specific training required for all flight and ground personnel whose job function could involve the recognition of CSFF. This training would
include: 1) recognition of CSFF; 2) the condition s that cause CSFF; 3) recognition and differentiation of the airplanes for which this exemption would or would not apply; 4) the limiting upper wing surface CSFF area; and 5) the Boeing B

- 737

- 700,

- 800 NG AFM CSFF
limitations. Additionally

, in line with a comment submitted by the Air Line Pilots Association, the FAA notes that t he Captain shall retain final authority for the safe accomplishment of the flight and may determine a stricter standard with respect to CSFF and flight conditions.

The FAA has determ ined that allowing Southwest Airlines to dispatch and takeoff B737

- 700
and

- 800 NG aircr aft with CSFF within the limitations specified in the FAA

- approved Boeing

AFM accompanied by the required training of associated personnel would not adversely
affect sa fety

. In addition, the FAA finds that a grant would be in the public interest because it
would decrease environmental impact of using deicing fluids and woul d increase operat ional efficiency and effectiveness by allowing specified aircraft as defined by t he Boeing analysis
and written in the FAA

- approved AFM limitations to dispatch and takeoff without having to
remove CSFF from the delineated upper wing surfaces.

To apply the revised B737NG AFM limitation for CSFF, Southwest Airlines must have the permis sible black lines defining the boundaries of the CSFF area on the upper wing in a manner which is clear and discernable by flight crew and ground personnel.5

In consideration of Boeing ’s aerodynamic analysis , t he FAA finds that the Boeing AFM
limitation re vision concerning CSFF on upper wing surfaces with respect to defined 737 aircraft models and types when combined with FAA

- approved procedures contained in the
associated Southwest Airlines manuals and the Southwest Airlines training program , and subject t o the discretion of the pilot

- in

- command provides a level of safety equivalent to the requirements of § 121.629(b).

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, Southwest Airlines is granted an exemption from

14 CFR § 121.629(b) that allows Southwest to take off an aircraft when frost, ice, or snow is adhereing to the wings , subject to the conditions and limitations described below

.

Conditions and Limitations

1. The dispatch and takeoff with CSFF on upper wing surfaces only applies to
Southwest Airlines Boeing 737

- 700,

- 800 NG aircraft as specified in the Boeing engineering and aeronautical analysis

.

2. Southwest Airlines will use and adhere to t he revised Boeing AFM miscellaneous limitations for CSFF in all instances concerning CSFF

.

3. This exemption does not relieve Southwest Airlines from any other limitation or requirement s with regards to deicing and anti

- icing operations

.

4. This exemption is provided and effective under the following conditions :

(a) The appropriate Southwest Airlines operations manual contains the following
limitations and conditions from the FAA a pproved B

- 737

- 700,

- 800 NG AFM :

Takeoff with cold soaked fuel frost on the wing tank upper surfaces is not permitted if any of the following conditions are present:

(1) The ambient air temperature is below +4 degree C , +39 degree fahrenheit

.

(2 ) The tank fuel temperature is below

- 16 degree C, +3 degree F

.

(3) There is cold soaked fuel frost on the wing tank upper surfaces that is beyond the lines defining the permissible cold soaked fuel frost area.

(4) There is precipitation or vis ible moisture (rain, snow, drizzle, or fog w ith less than 1 mile visibility).6

(b) FAA has approved Southwest Airli nes CSFF pilot training program and any assigned pilots must have been trained prior to applying CSFF exemption
standards

.

(c) Southwest Airlines must provide ground and operational training to all pilot s and ground personnel to ensure each is able to clearly discern the applicability of the CSFF exemption requirements , to include identifying which Southwest
Airline s aircraft have the pai nted CSFF upper wing areas. The training must include recognition of those airplanes approved for CSFF exemption.

(d) The pilot

- in

- command retains final authority for takeoff of a flight with CSFF

.

This exemption terminates on November 30, 2017 , unless soo ner superseded or rescinded.

Issued in Washington, DC, on October 23, 2015.

.

/s/ John Barbagallo Deputy Director, Flight Standards Service