AFS-13-564-E

Exemption No. 10827A

UNITED STATES OF AMERICA

DEPARTMENT OF TRANSPORTATION

FEDERAL AVIATION ADMINISTRATION

WASHINGTON, DC 20591

 

In the matter of the petition of 

 

DELTA AIR LINES, INC. Regulatory Docket No. FAA-2011-0618

 

for an exemption from § 121.333(e)(2) 

of Title 14, Code of 

Federal Regulations 

 

DENIAL OF PETITION FOR RECONSIDERATION

 By letter dated September 23, 2013, Mr. Stephen M. Dickson, Senior Vice President Flight 

Operations, Delta Air Lines, Inc., (Delta), P.O. Box 20706, Atlanta, GA 30320 petitioned the 

Federal Aviation Administration (FAA) on behalf of Delta for reconsideration of the FAA’s 

July 24, 2013 denial of Delta’s petition for exemption from § 121.333(e)(2) of Title 14, Code of 

Federal Regulations (14 CFR). If granted, that exemption would allow Delta aircraft, following 

a cabin depressurization event, to initially descend to 14,000 feet and subsequently descend to 

10,000 feet no later than 30 minutes after the initial depressurization event, without carrying the 

additional supplemental oxygen required by §121.333(e)(2).

The petitioner requests relief from the following regulation:

Section 121.333(e)(2), prescribes, in pertinent part, that supplemental oxygen for emergency 

descent and for first aid; turbine engine powered airplanes with pressurized cabins, that:

(e) Passenger cabin occupants. When the airplane is operating at flight altitudes above 

10,000 feet, the following supply of oxygen shall be provided for the use of passenger cabin 

occupants:

(2) When an airplane is operated at flight altitudes up to and including flight level 250 and 

cannot descend safely to a flight altitude of 14,000 feet within four minutes, or when an airplane 

is operated at flight altitudes above flight level 250, oxygen shall be available at the rate 

prescribed by this part for not less than 10 percent of the passenger cabin occupants for the entire 

flight after cabin depressurization, at cabin pressure altitudes above 10,000 feet up to and 

including 14,000 feet and, as applicable, to allow compliance with §§ 121.329(c)(2) and (3), 

except that there shall be not less than a 10-minute supply for the passenger cabin occupants.

The petitioner supports its request with the following information:
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Delta states that the FAA “improperly based its risk assessment on the difference of an effective 

oxygen altitude difference of 4000 feet and a 30-minute duration at 14,000 feet when it should 

have been based on an effective difference of 1750 feet and 18 minutes at 14,000 feet.” Delta 

claims that the rule only requires mass flow oxygen at 14,000 feet equivalent to breathing 

ambient air at 12,250 feet and, therefore, asserts that the FAA should have considered the 

difference between 12,250 feet and 14,000. Further, Delta suggests that the FAA should have 

considered the effects of decompression for an 18-minute period to account for a 12-minute 

supply of supplemental oxygen. 

Delta asserts that the FAA does not provide detail on what “serious problems for passengers with 

compromised cardiovascular and pulmonary function” could occur following a decompression 

event. Delta explains that the possibility of decompression injury falls into two categories: 

hypoxic and barotraumatic. In regard to hypoxia, Delta cites the World Health Organization 

respiratory functional assessment classification and provides information on the possible effects 

of altitudes on each of these classes. Delta indicates that individuals in certain respiratory classes 

should travel with their own supplemental oxygen and that the oxygen flow required by 

§ 25.1443(c)(1) would not produce a sufficient amount of oxygen to sustain the appropriate 

“oxyhemoglobin saturation rate” for these people. Further, Delta states that barotraumatic 

injuries are the most common injuries due to decompression and that levelling off at 14,000 feet 

for 30 minutes will reduce risk by allowing time for equalization of pressure within the body’s 

inner air chambers and the atmosphere. 

Delta highlights the existence of other current U.S. Federal Aviation Regulations which allow

passenger operations at the altitude Delta seeks without the carriage of passenger supplemental 

oxygen. Delta contends that passengers carried under these operations are no different 

physiologically than the passengers carried aboard part 121 operations. Further, Delta mentions 

Operations Specification (OpSpec) A525 that allowed 20 minutes at 14,000 feet without 

supplemental oxygen.

Delta asserts that, in the FAA’s initial denial, the “the probability of a decompression event was 

overstated because the FAA applied data from Service Difficulty Reports (SDRs) and did not 

factor in the number of actual operations.” Further, Delta questions the FAA’s rationale in basing 

its analysis on all depressurization events regardless of severity. Delta states that, as of July 

2013, looking back 66 months, it recorded 89 events where some level of cabin pressurization 

was compromised. Delta contends that none of these events would be considered explosive or 

rapid and that there were 19 events where the passenger oxygen system was activated. 

Delta maintains that the exemption would reduce controlled flight into terrain (CFIT) risk that it 

identified as a hazard through its Safety Management System. Delta estimates the probability of 

an aircraft having a depressurization event requiring oxygen mask deployment in a terrainrestricted area as approximately one in 50 million flights.

Finally, Delta contends that relief from the regulation will reduce flight times that will result in

decreased radiation exposure to passengers and flight crews. Delta suggests that the increase in 

flight time to avoid high terrain increases the risk of cancer due to radiation exposure.
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The Air Line Pilots Association International submitted comments in support of the petition for 

reconsideration, suggesting that the exemption would not endanger passenger safety but would 

enable routes that would reduce CFIT risk.

The FAA's analysis is as follows:

The FAA has reviewed its rationale in Denial of Exemption No. 10827 issued to Delta on 

July 24, 2013 and its petition for reconsideration. In that denial, the FAA found that Delta had 

not identified how it would be in the public interest, and how its proposal would not adversely 

affect safety or how a grant of exemption would provide a level of safety at least equal to that 

provided by § 121.333. The FAA also determined that Delta’s proposal to keep an airplane at an 

altitude above 10,000 feet to remain clear of terrain and obstacles would expose passengers to higher 

cabin altitude without sustaining oxygen, resulting in an unacceptable transfer of risk to passengers. 

Upon reviewing the petition for reconsideration, the FAA still finds that a grant of exemption 

would not be in the public interest and would not provide a level of safety equivalent to that 

provided by the current regulations.

Upon receiving a denial of exemption, § 11.101 states that a petitioner may ask the FAA to 

reconsider its petition for exemption. The petition for reconsideration must show a significant 

additional fact that was not presented in the original petition, that the FAA made an important 

factual error in the denial, or that the FAA did not correctly interpret a law, regulation, or 

precedent. As discussed below, Delta asserts that, in denying its petition, the FAA incorrectly 

assessed the risk to passengers.

Delta’s assumption that FAA did not consider supplemental oxygen already installed on aircraft 

is incorrect. FAA based its risk analysis on a clear understanding of Delta’s request, as described 

in the initial denial: 

The petitioner has stated the installed drop-down oxygen system will provide oxygen to 

100 percent of the passengers for the first 12 minutes following the decompression event. 

The petitioner did not propose to provide supplemental oxygen to passengers for the 

remaining 18 minutes between the cessation of the drop-down oxygen and the descent to 

10,000 feet. Section 121.333 would require oxygen for 10 percent of the cabin occupants 

during those 18 minutes.

The FAA maintains its determination that the exemption would not provide a level of safety 

equivalent to that provided by the rule. Delta’s initial petition relied heavily on increased safety 

benefit related to CFIT. In its petition for reconsideration, Delta admits that increased safety 

benefit by way of reducing CFIT risk would be realized in “approximately one event in 50 

million flights.” In this area, the FAA continues to find that the petitioner has already developed 

procedures to mitigate the risk of flying over critical terrain, including additional training, flight 

planning, and restrictions on the deferral of equipment. Delta states that special routing to avoid 

high-terrain areas results in increased flight times compared to other carriers (part 125, part 135, 

and EASA carriers). It is Delta’s belief that relief from the regulation will enable it to fly shorter 

routes. The FAA finds that these benefits, particularly the benefit of decreased flight time, do not 

outweigh the increased risk to passengers, particularly children, the elderly, and passengers with 

cardiopulmonary conditions. 
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In its petition for reconsideration, Delta provided information on physiological effects imposed 

on the traveling public and risks of decompression injury, such as hypoxia or barotraumatic 

injury. Delta is correct in its assertion that there is no data substantiating the FAA's claim that 

passengers with compromised cardiovascular and respiratory function may be at increased risk 

when exposed to a 14,000 feet ambient environment. However, as evidenced by data in the 

clinical literature, some patients in this group desaturate even at ground level. The index of 

concern for compromised passengers at 14,000 feet is provided entirely through the clinical 

judgement of the medical community based on training and experience. It is unlikely that an 

Institutional Review Board would approve a study of this nature involving human subjects. 

Therefore, the altitude-related risk remains unquantified. 

Delta also stated that passengers with reduced physical capacity (qualified as Class II) should 

provide their own supplemental oxygen. While Delta is correct that individuals in certain 

conditions should travel with their own supplemental oxygen, the FAA recognizes that this is not 

always true in practice because many passengers may not realize their physical condition and 

associated risk since they do not need supplemental oxygen at rest or at ground level. In regard to 

barotrauma and gas embolism issues, the FAA contends that these issues are more related to the 

initial decompression event and are of secondary importance to the 14,000 feet hypoxia concern. 

The FAA finds that providing passengers with less emergency supplemental oxygen than 

required by the regulation is less safe and would unacceptably transfer risk to passengers.

Delta cites sections of parts 135 and 91 that allow passenger-carrying operations at the requested 

altitude without carriage of supplemental oxygen. While these sections may allow for passengercarrying operations at Delta’s requested altitude under those operating rules, the regulation that 

Delta must demonstrate an equivalent level of safety for is § 121.333, not regulations under 

parts 91 or 135. As required for a Petition for Reconsideration, Delta has not presented any 

significant additional fact that was not presented in the original petition to show that Delta’s 

request would provide a level of safety equivalent to that provided by the current regulation.

The FAA finds also that Delta has failed to demonstrate how an exemption is appropriate in its 

particular circumstances as compared to other part 121 air carriers. The basis upon which Delta 

is asking for relief would be essentially the same for other part 121 carriers. Therefore, an 

exemption is not the appropriate mechanism for accomplishing a change of general applicability

such as presented here. 

Additionally, the FAA finds that Delta has not provided any new information in regard to the 

issuance of OpSpec A525. In the FAA’s July 24, 2013, Denial of Exemption letter, the FAA 

properly considered and explained the FAA’s rationale for issuing OpSpec A525 and explained

the differences between the risks posed to military members and the risks posed to non-military 

passengers. 

Delta states that the FAA’s method of analysis based on the SDR is statistically flawed and 

questions the FAA’s rationale in including depressurization events of all levels of severity. The 

FAA emphasizes that a statistical analysis was not performed. Delta asserts that only 40 of the 66 

SDRs identified by the FAA in its exemption denial involved an actual decompression event and 

that, of these 40 SDRs, 17 events involved oxygen mask deployment. Despite any weakness in 

the FAA’s initial analysis, Delta admits in its petition for reconsideration that it “recorded 89 

events where some level of cabin pressurization was compromised” in the past 66 months. This 
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demonstrates that cabin depressurization and mask deployment occur with enough frequency to 

merit concern. These events support the FAA’s analysis that the risk of decompression, rapid or 

gradual, is not low, particularly if the number of incidents recorded by Delta is comparable to 

other part 121 carriers. Additionally, the FAA contends that slow decompression can be just as 

dangerous as rapid decompression. By its nature, rapid decompression commands attention. On 

the other hand, slow decompression may go unnoticed and the resultant hypoxia may be 

unrecognized by the pilot.1 The FAA concludes that Delta has not provided any additional or 

new information in this area that would warrant granting the petitioner’s request at this time.

Lastly, Delta contends that the reduced flight times enabled by the exemption will reduce 

radiation exposure and, therefore, risk of cancer for flight crews and passengers. The FAA 

recognizes that flight crews are occupationally exposed to ionizing radiation and that the 

probability of radiation-caused cancer is related to the total amount of radiation accumulated by 

an individual.2 The FAA points out that, in addition to reducing flight time, reducing flight 

altitude is also a way to reduce exposure to ionizing radiation.3 The FAA concludes that the 

environmental concerns cited by Delta as justification for the requested relief are not directly 

concerned with passenger safety during an emergency and are, therefore, tangential to the 

oxygen issue. The FAA finds that Delta has provided insufficient data to substantiate a claim that 

any reduced risk with regard to radiation exposure offsets the increased risks assumed by 

passengers related to supplemental oxygen. As such, the FAA finds that Delta has not provided 

sufficient information or evidence to show that a grant would be in the public interest or would 

provide a level of safety at least equal to that provided by the rule.

The FAA’s Decision:

In consideration of the foregoing, I find that a grant of exemption would not be 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, the petition of Delta Air Lines, Inc. for an exemption from 

14 CFR § 121.333(e)(2) is hereby denied. 

Issued in Washington, DC, on September 18, 2014. .

/s/

Michael G. Whitaker

Deputy Administrator

 1 FAA Advisory Circular AC-61-107B (3/29/2013), Ch. 2, ¶ 2-7(e)(3). 2 FAA Advisory Circular AC-120-61A (7/6/2006), Ch. 8, ¶ 1 Risk Associated with Exposure. 3 FAA Civil Aerospace Medical Institute, What Aircrews Should Know About Their Occupational Exposure to 

Ionizing Radiation. Springfield: National Technical Information Service, 2003.