BEFORE THE FEDERAL AVIATION ADMINISTRATION WASHINGTON D.C.

Docket FAA-2011-___________

PETITION OF DELTA AIR LINES, INC. FOR AN EXEMPTION June 6, 2011

Delta Air Lines, Incorporated, operating certif icate DALA026A, hereby petitions the Federal Aviation Administration (FAA), pursuant to 14 C. F.R. Part 11 for partial relief from Federal Aviation Regulation (FAR) §121.333 (e)(2), provided certain conditions and limitations are met.

All references to altitude will be in Mean Sea Level (MSL) unless specifically stated otherwise.
Use of the name Delta or Delta Air Lines is to be considered the same as Delta Air Lines, Incorporated.

Sections of the FARs Affected:

Section §121.333(e)(2), Supplemental oxygen for em ergency descent and fo r first aid; turbine engine powered airplanes wi th pressurized cabins, st ates in pertinent part:
(e) Passenger cabin occupants. When the airpla ne is operating at f light altitudes above 10,000 feet, the following supply of oxygen shall be provided fo r 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 ab ove flight level 250, oxyg en shall be available at the rate prescribed by this part for no t less than 10 percent of the passenger cabin occupants for the entire flight after cabin de pressurization, at cabi n 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.

Requested Relief:

Delta Air Lines requests exemption to allow an ai rplane following a cabin depressurization event to initially descend to 14,000 f eet and subsequently descend to 10,000 feet no later than 30 minutes after the initial depressu rization event, without carrying the additional supplemental oxygen required by Section §121.333(e)(2). Petition of

DELTA AIR LINES, INC. OPERATING CERTIFICATE DALA026A

For exemption of certain requirements of 14 C.F.R. §121.333(e)(2)Petition for Exemption - (FAR) §121.333 (e)(2) Delta Air Lines, Inc. June 6, 2011 Page 2

This exemption request adheres to the premise of §121.329(c)(1) which allows turbine powered airplanes to operate at cabin pr essure altitudes above 10,000 feet up to and including 14,000 feet for 30 minutes before requiring addition al supplemental oxygen for 10 percent of the passengers. §121.329(c)(1) states th e following in pertinent part:

§121.329 - Supplemental oxygen for sustenance : Turbine engine powered airplanes. (c) Passengers. Each certificate holder shall provide a supply of oxygen for passengers in accordance with the following: (1) For flights at cabin pre ssure altitudes above 10,000 feet , up to and including 14,000 feet, enough oxygen for that part of the flight at those altitudes that is of more than 30 minutes duration, for 10 percent of the passengers.

Background:

The last amendment to the passenger supplementa l oxygen carrying requir ements was in 1958. The amendment established a requ irement to supply supplemental oxygen for 10 percent of the passengers for the entire time the aircraft cabi n altitude is above 10,000 feet MSL up to and including 14,000 feet MSL after a depr essurization event. This part of the rule applied to aircraft certified to operate to 25,000 feet MSL that could not descend to 14,000 feet MSL within four minutes or any aircraft operatin g above 25,000 feet MSL. For the maximum size of aircraft operating at that time the rule would requ ire the carriage of supplemental oxygen for approximately 15 passengers if the aircraft could not descend to 10,000 feet MSL after a depressurization event and the no rmal passenger oxygen system supply was not enough for the time above 10,000 feet MSL. This would genera lly require the carriage of 15 portable oxygen bottles.

Manufacturers design most modern aircraft to descend from the maximum certified altitude to 14,000 feet MSL within four minu tes with enough supplemental oxygen to reach 10,000 feet within the normal passenger oxyg en system supply. Passenger oxygen systems are certified to a minimum of 12 minutes for aircraft operated by Delta Air Lines. In many areas of our operation Delta has specifically designed depressurization routes that allow the aircraft to descend to 10,000 feet MSL within the 12 minu te passenger oxygen supply to comply with §121.333(e)(2). Once at or below 10,000 feet MSL oxygen is no longer required for compliance with §121.333(e)(2). Depending on the airplane location and surrounding terrain, these routes may require the aircraft to be operated below grid MORAs (Minimum Off Route Altitudes) on defined routes. In layman ’s terms, this procedure often requir es the pilots to navigate around areas of high terrain instead of flying above the terrain.

Delta operates to over seventy countries within six continents. We consistently use our Safety Management System (SMS) to identify hazards an d reduce risks to our operation. Due to our global network, our flight crews could operate in many theaters spanning six continents in a given month. This makes Delta unique compared to the majority of other air carriers who do not need to prepare their flight crews for such a diverse operation. Using our internal risk assessments, SMS, and pilot training programs we develop procedures and curricula to prepare our crews, which will be described later in this pe tition. One of these procedures and challenges is operating over critical terrain. Ninety-five pe rcent of the routes oper ated by Delta Air Lines allow an immediate descent to 10,000 feet MSL after a depressu rization. However, approximately five percent of the operation is over critical terrain airspace where the grid MORAs are above 10,000 feet and immediate de scent to 10,000 feet is not possible without being established on a published airway or a Delta-engineered ro ute. These areas are primarilyPetition for Exemption - (FAR) §121.333 (e)(2) Delta Air Lines, Inc. June 6, 2011 Page 3

in Western Canada, Central America, South America, the Middle Ea st, the Himalayas and Greenland.

A depressurization event is a higher risk situation. The flight cr ew must don oxygen masks, deal with the situation that caused the depressuriza tion, perform an emergency descent to a safe altitude and, if over critical terrain, transition to a critical terrain route in order to avoid the terrain while descending to 10,000 feet MSL wi thin the time limitation of the passenger supplemental system. In certain parts of our netw ork, such as South America, pilots face the likelihood of executing these critical terrain proced ures at night or in the weather, greatly adding to the complexity of the maneuver and exacerbating the challenge of maintaining situational

awareness.

In order to comply with §121.333(e)(2 ), Delta employs three methods:

1. Avoid the critical terrain areas where desce nt to 10,000 MSL is not possible within the supply of the onboard oxygen system. Th is option creates less efficient routes.
2. Operate over the terrain wher e immediate descent to 10,000 f eel MSL is not possible but provide the crews with specific critical terrain diversion routes that allow initial descent to 14,000 feet then further descent to 10,000 feet MSL within the time of standard oxygen supply (normally 12 minutes).
3. Certain fleets have been conf igured with additional supplemental oxygen to allow additional time to remain at 14,000 feet MSL. All of the B- 777 aircraft operated by Delta carry 32 bottles of supplemental oxygen. For certain B-767-300 aircraft, Delta has the capability to place a minimu m of 24 supplemental bottles in specially configured overhead bins. In this case the bottles take up overhead passenger carry-on storage capacity by at least six bins. The cost to carry the extra o xygen bottles in direct fuel cost for the B-777 is $339,212.00 annually based on fuel price as of March 23, 2011. This is fuel that is burned in order to carry the extr a weight. In addition to the increased cost and fuel burn, the carriage of the additional oxygen bottl es increases Delta’s carbon footprint and is not environmentally friendly.

Through our Safety Management System (SMS), De lta has previously identified operations over high terrain as an increased risk operation. Cu rrently there are several ri sk mitigation elements in place. These include:

• Theater Qualification for the pilots

• Pilot qualification training and continuing qua lification training with respect to critical terrain procedures

• Engineered terrain avoidance routes

• Flight planning system identifying to the flight crews when a ro ute requires special depressurization routes

• Aircraft theater equipment re strictions requiring certain operational equipment above regulatory requirements, e.g., not always allowing Minimum Equipment List (MEL) relief for enhanced ground proximity warning systems depending on the planned route

While these mitigations make operations in areas of high terrain acceptable, there is still the latent condition of controlled flight into terrain (C FIT) inherent anytime the aircraft is required to operate below a grid MORA. Raising the init ial descent to 14,000 feet MSL for 30 minutes removes the vast majority of CFIT risk associated with critical terrain areas. Attached to this request are 8000 foot MSL and 12,0 00 foot MSL maps for a parts of South America, Middle East and Greenland, illustrating the redu ction of the terrain risk by in itially descending to 14,000 feet MSL versus the current requirement to descend to 10,000 feet MSL. See Appendix 1.Petition for Exemption - (FAR) §121.333 (e)(2) Delta Air Lines, Inc. June 6, 2011 Page 4

Justification for exemption:

Delta’s goal of this exemption request is to reduce CFIT risk by reducing the complexity of the operation and improving the situational awareness of our flight crews in the first few minutes after a depressurization event. A typical CFIT accident has a root cause of the pilot losing situational awareness generally due to a flight deck distraction. Typical accident scenarios have an error chain that compounds throughout the ev ent. By its very natu re, a depressurization event is a higher risk event posing a significant distraction that th e flight crew must deal with. The requirement to descend into areas of high terrain adds another level of complexity to the operation. Other than the issue of the rule requiring a supply of oxygen be available to 10 percent of the passengers while operating above 10,000 feet up to and including 14,000 feet, it is self-evident that flying over high terrain poses a lower degree of CFIT risk than operating around the terrain. Our petition demonstrates th at we can remove a significant amount of CFIT risk associated with a de pressurization event and provide at le ast an equivalent level of safety with respect to the physiologica l aspect of 121.333(e)(2). At th e same time, the Delta proposal will remove a hazardous material s risk associated with carryin g large quantities of oxygen aboard the aircraft.

Delta’s Flight Safety and Quality Assurance de partments have conducted a 10-year review of NTSB files for United States air carriers and found 8 reports where a rapid decompression was part of the incident or accident. We limited ou r review to United States air carriers because all aircraft are under one set of maintenance rules an d are established in the required aging aircraft programs as appropriate. Each of these events is cited below. Of the 8 events, 2 occurred during a ground operation where a door was op ened while the aircraft had some level of pressurization. The other 6 depre ssurization events occurred within the first 25 minutes of flight based on the narrative of the reports.

• MIA01FA029 , (Miami, FL – 2000) – After takeo ff aircraft did not pr operly pressurize. Ground accident due to aircraft remaining pr essurized on the ground after landing and a Flight Attendant being thrown from aircraft while opening a door.

• DEN05LA077, (Denver, CO – 2005) – Shortly af ter takeoff part of the nose landing gear punctured the forward pressure bulkhead.(belo w 10,000 feet MSL). Ai rcraft returned for landing.

• DCA05MA071, (Chicago, IL – 2005) – Aircraft inad vertently pressurized on the ground. Flight Attendant thrown from the aircraft while opening the door

• SEA06LA033, (Seattle, WA – 2005) - During the c limb out, at approximately 26,000 feet cargo door skin developed a 12 inch by 6 inch hole. Flight returned for landing.

• NYC07LA121, (Syracuse, NY – 2007) - After de parture, the airplane was climbing through approximately 20,000 feet mean sea level (MSL) the aircraft developed a 12-inch by 5-inch fuselage skin tear in front of the cargo door. F light diverted to a nearby suitable airport.

• DCA09FA065, (Charleston, WV – 2009) – Approx imately 25 minutes af ter takeoff aircraft developed a 18-inch by 12-inch flap in the skin. Flight diverted to a nearby suitable airport.

• DCA11FA004, (Miami, FL – 2010) - Approximatel y 25 minutes after take off at 31,000 feet MSL aircraft developed a hole of about 1 foot by 2 feet. Flight returned for landing.

• DCA11MA039 , (DCA, DC – 2011) – Approximately 20 minutes after takeo ff at approximately 34,000 feet MSL aircraft developed a 5 foot by 1 foot hole over the passenger cabin aft of the wing. Flight diverted to a nearby suitable airport

In the past 10 years Delta Air Lines has flow n approximately 26,284,023 flight hours and 11,313,568 flights (data combined with previous Northwest Airlines). Considering Delta and Northwest each had one event, we calculate th e actual rate of occurrence at 7.609 x 10 -8 perPetition for Exemption - (FAR) §121.333 (e)(2) Delta Air Lines, Inc. June 6, 2011 Page 5

flight hour with a 95% conf idence interval of 1.0546 x 10 -7 . Our calculations appear to be consistent with a recent publication by the FAA noted below. During our research Delta did not find any events within the past 10 years where a Delta or a Northwest aircraft experienced a rapid depressurization event over critical te rrain where an immediate descent to 10,000 feet was not possible. Both events associated with Delta and Northw est occurred within the first 20 minutes of departure. It is our contention that relief from §121.333(e )(2) as requested would be inconsequential based on event probability alone.

In a recent final rule (Docket No. 2011-0186) the F AA stated the following with respect to use of the oxygen system other than a malfuncti on of the pressuri zation system:

“The FAA has conducted a risk analysis to a ssess the safety implications of temporarily not having supplemental oxygen available inside lavatories. To support the risk assessment, earlier studies involving passen gers' use of oxygen were reviewed. For a different rulemaking, the FAA tasked the Aviation Rulemaking Advisory Committee (ARAC) to make recommendations for safety standards when airpla nes are operating at high altitudes. As part of its effort, the ARAC did a comprehensive assessment of the frequency and nature of the need for suppl emental oxygen systems in service. The ARAC identified 2,800 instances over a 40-year period and categori zed them by cause, severity, and consequence. The majority of these in stances were caused by malfunctions of the cabin pressurization system. However, in none of those 2,800 instances was there a loss of life due to lack of oxygen . The ARAC used these data in making recommendations to the FAA on future rulemaking.

The FAA has reviewed the service history si nce the ARAC recommendations were made and found that the types and frequencies of incidents, as well as their causes, are consistent with the historical record. The relative risks and service history have not changed in any significant way since the ARAC recommendations were issued. With respect to this SFAR, the only affected ar eas of the airplane are the lavatories, as opposed to the earlier assessments, which applied to the entire airplane. The lavatories are sporadically occupied during flight, an d by a small number of passengers at any given time. This limits the potential impact on safety.

The ARAC found that the frequency of occurrences necessitating the use of oxygen was around 10

- \8\/flight-hour for causes other than a malfunction of the pressurization system (these tend to be slower losses of pressure, or are identified at lower altitudes, and therefore are not as critical for this action). The probability that a lavatory will be occupied at any given moment is not known. It is not 100% and it is not 0%. If, for the purpos es of this assessment, we assume the probability is 50%, then the probability of a person in a lavatory needing oxygen is ~5
x 10 -9 /flight-hour.” (Emphasis added)

When we consider that 95% of our operation is over terrain that allows an immediate descent to 10,000 feet MSL the potential impact to safety is at least comparable to the FAA’s analysis within Docket No. 2011-0186

Support for Requested Action and Equivalent Level of Safety

In order to demonstrate no adverse effect to pu blic safety, Delta conferred with Dr. Allen J. Parmet, an aerospace medical doctor, to establish the physiological aspects of this proposal forPetition for Exemption - (FAR) §121.333 (e)(2) Delta Air Lines, Inc. June 6, 2011 Page 6

exemption. Specifically we requested that Dr. Parmet provide an analysis so Delta could compare the physiological as pects between §121.329(c)(1), Supplemental oxygen for sustenance: Turbine engine powered airplanes and this proposal to be exempt from supplying the additional oxygen requ ired by §121.333(e)(2). See Appendix 2.

Additionally, we wanted to assess whether or not this proposal would deliver an equivalent level of oxygen to passenger aircraft operated unde r §121.329(c)(1) if not required to operate under §121.333(e)(2). Dr. Allen J. Parmet provided a posi tion paper to Delta Air Lines on 3/24/2011. Following receipt of Dr. Parmet’s position paper Delta requested a dditional data and analysis for the following two scenarios: 1) Slow decompression at 42,000 f eet with descent to 14,000 feet, and 2) Rapid decompression at 42 ,000 feet with descent to 14,000 feet. We wanted to assure that individuals breathing supplemental oxygen will have an oxygen level comparable to an individual at 14,000 feet withou t supplemental oxygen. We requ ested that Dr. Parmet provide the oxygen values for a slow and a rapid decompre ssion assuming an initial oxygen flow rate of 3.6 L/min. for four minutes and a lower rate of 0.8 L/min. fo r the duration of the oxygen generator time. The slow deco mpression chart represents a co nservative view of either a smaller aircraft skin failure or a loss of pres surization system where the cabin reaches 25,000 feet before the passenger begins the use oxygen. The systems are designed to automatically deploy the oxygen masks if the cabin altitude exceeds 14,000 feet . For the rapid decompression an assumption was made that the cabin altitude reached 40, 000 feet before the passengers began to use the oxygen.

Decompression Incident Scenarios

Scenario 1: Slow decompression at 42, 000 feet with descent to 14,000 feet

Elapsed Time In Minutes Cabin Altitude (Aircraft Altitude) Cabin Barometric
Pressure (PB) Cabin Partial Pressure of Oxygen (PO2) Arterial Oxygen Level (PaO2) Equivalent Altitude Time of Useful Consciousness

0 8,000’ 42,000 565 mmHg 118 mmHg 69 mmHg N/A Indefinite

1 15,000’ 32,000’ 429 mmHg 90 mmHg 45 mmHg N/A Indefinite

2 25,000’ 25,000’ 282 mmHg 59 mmHg 30 mmHg N/A 3-5 minutes

2 25,000’ 25,000’ 282 mmHg Oxygen Generator Used
@ 3 LPM 135 mmHg 87 mmHg ~3500’ Indefinite

4 14,000’ 14,000’ 446 mmHg Oxygen Generator Used
at 0.8 LPM 110 mmHg 61 mmHg ~10,000’ Indefinite

16 14,000’ 14,000’ 446 mmHg Oxygen Generator Expired 94 mmHg 48 mmHg N/A Indefinite

Note: Equivalent altitudes derived from: Fundam entals of Aerospace Medicine, Fourth EditionPetition for Exemption - (FAR) §121.333 (e)(2) Delta Air Lines, Inc. June 6, 2011 Page 7

Scenario 2: Rapid decompression at 42, 000 feet with descent to 14,000 feet

Note: Equivalent altitudes derived from: Fundam entals of Aerospace Medicine, Fourth Edition

Key points of Dr. Parmet’s position paper and decompression analysis:

• At a cabin altitude of 25,000 feet MSL at a 3.6 L/min flow rate the passenger is at an altitude equivalent of approx imately 3500 feet MSL. At a ca bin altitude of 14,000 feet MSL at a 0.8 L/min flow rate the passenger is at an altitude equiva lent of approximately 10,000 feet MSL.

• At a cabin altitude of 40,000 feet MSL at a 3.6 L/min flow rate the passenger is at an altitude equivalent of approx imately 3000 feet MSL. The reason for the lower equivalent altitude vs 25,000 feet is due to the higher barometric pre ssure at the lower altitude which creates more mixing of the 21% ox ygen ambient air with the oxygen being delivered.

• The passenger in both cases will be provided with an initial oxygen equivalency lower than 8000 feet and by the time the oxyg en generator expires (approximately 12 minutes) will be no higher th an 10,000 feet. From this point the passenger will be breathing ambient air of 14,000 feet for ap proximately 18 minutes when our procedures will allow the aircraft to have descended to at least 10,000 feet MSL.

• By 15,000 feet the use of supplemental oxyg en is not necessary for individuals with normal pulmonary function.

• For individuals with compromised pulmonary function the aircraft oxygen system will initially supply the necessary oxygen equivale nt to the passenger carried oxygen systems Elapsed Time In Minutes Cabin Altitude (Aircraft Altitude) Cabin Barometric
Pressure (PB) Cabin Partial Pressure of Oxygen (PO2) Arterial Oxygen Level (PaO2) Equivalent Altitude Time of Useful Consciousness

0 8,000’ 42,000 565 mmHg 118 mmHg 69 mmHg N/A Indefinite

0.1 40,000’ 42,000 141 mmHg 32 mmHg 10 mmHg N/A 10 seconds

0.2 40,000’ 40,000’ 141 mmHg Oxygen Generator Used
@ 3 LPM 141 mmHg 90 mmHg ~3,000’ Indefinite

2 25,000’ 25,000’ 282 mmHg Oxygen Generator Used
@ 3 LPM 135 mmHg 87 mmHg ~3500’ Indefinite

4 14,000’ 14,000’ 446 mmHg Oxygen Generator Used
at 0.8 LPM 110 mmHg 61 mmHg ~10,000’ Indefinite

16 14,000’ 14,000’ 446 mmHg Oxygen Generator Expired 94 mmHg 48 mmHg N/A IndefinitePetition for Exemption - (FAR) §121.333 (e)(2) Delta Air Lines, Inc. June 6, 2011 Page 8

allowed on the aircraft. When the system transitions to the lower flow the passenger should be able to resume th eir own system use or be ai ded by a first aid bottle.

Delta Air Lines Analysis and Public Interest:

FAR §121.329(a)(1) allows indefinite flight at a ca bin altitude of 10,000 feet MSL then allows 30 minutes of flight up to and in cluding a cabin altitude of 14,000 without suppl ying any additional passenger oxygen. With the requ irement of §121.333(e)(2), whic h references compliance to §121.329(c)(2) and (3), 100 percent of the passenger s will have access to at least a 12 minute oxygen supply for all Delta aircraft. During this time the passenger will be supplied with an oxygen equivalent of 10,000 feet MSL or lower. Delta is requesting to remain at 14,000 feet MSL for a maximum of an additi onal 18 minutes after the deplet ion of the oxygen generators before completing a descent to or below 10,000 feet MSL. Th erefore, we believe that our proposal is still more conservative than an op eration that is only required to comply with §121.329 which allows 30 minutes at 14,000 feet MSL with no supplemental oxygen.

While we would concur that other regulatory statutes do not directly effect the determination for granting an exemption, we believe it is import ant for the FAA to recogn ize that several foreign regulators allow flight up to 30 minutes at cabin altitudes above 10,000 feet MSL before requiring additional passenger oxygen. EASA (European Avia tion Safety Agency) allows operations above 10,000 feet MSL up to and including 14,000 feet MSL for 30 minutes before requiring additional oxygen for the passengers. See Appendix 3. Many of the air carriers certified by EASA are also certified by the Federal Av iation Administration under 14 CFR §129. In cases where Delta has to route aircraft around the areas of terrain above 8,000 feet MSL in order to comply with §121.333, these other carriers are oper ating on more direct and effi cient routes. For the remote chance of a Delta aircraft having a decompression over a critical terrain area, the pilots would be restricted on routing options compared to a carrier not restricted by 121.333(e)(2). This creates the potential of greater flight time to landing after a decompression.

Delta completed a review to modify and equip aircraft that operat e in areas of critical terrain with additional supplemental oxygen to allow operat ions on the same routes as our competitors. To equip all aircraft that operate on routes over critical terrain would require the purchase of over 9700 supplemental oxygen bottles. Using a cost estimate of $100.00 each results in a cost just under one million dollars. The annual fuel expense to carry the extra bottles on fleets that operate in areas of critical terrain would exceed 6 million dollars per year on a fleet wide basis. The engineering, onboard storage, installation and maintenance costs would far exceed this cost and put Delta at an economic disadvantage to our competitors who are not required to comply with §121.333(e)(2). Additionally, if Delta proceed ed with the equipage op tion, it would create increased greenhouse gas effect s making this option economically and environmentally prohibitive. If the exemption is denied, there is a high probabilit y that the cost to operate would be passed on to the traveling public. Consequent ly, after carefully considering the fact that the additional oxygen required by §121.333(e)(2) has never been used to serve a passenger during operations at Delta, combined with the enviro nmental and economic impact associated with equipping the fleet, equippi ng with additional suppl emental oxygen is not in the public’s best interest.

Delta has also identified a hazardous materials ri sk associated with carrying large quantities of oxygen. In the event several of these bottles were turned on in a confined space with other flammable materials the area could ignite creating a severe fire and possible explosion. Considering Delta has never experienced a flight whe re these bottles were ac tually required due to a loss of pressurization along with the very lo w probability of a depressu rization event over aPetition for Exemption - (FAR) §121.333 (e)(2) Delta Air Lines, Inc. June 6, 2011 Page 9

terrain critical area, Delta contends it is in the public interest to grant this exemption so we may remove this hazard from the aircraft currently equipped. Equipping other aircraft would simply provide more opportunities for the event described. While an argument could be made to secure the bottles in a locked area, this would seem to defeat the purpose of “availability” as well as create additional expense to configure the aircraft.

Proposed Conditions and Limitations for Grant of Requested Exemption

Delta proposes the following as cond itions for grant of the exemption:

1. Delta will maintain a database/history for each depressurization event where oxygen masks deployed. The data required will at a minimum contain:

a. Flight number and date b. City pair

c. Departure time d. Time after takeoff of occurrence

e. Area of decompression (critical terrain)
f. Aircraft altitude of event
g. Maximum cabin altitude experienced h. Cause of the event i. Narrative summary
2. For this exemption to remain in effect, Delta must maintain or exceed its current record of 7.6 x 10 -8 events per flight hour (within 3 standa rd deviations), for events that exceed a cabin altitude of 25,000 feet MSL over a 10 rolling year period.
3. At least once each quarter Delta will review items 1 and 2 with the Principal Operations Inspector to ensure compliance.

Request for Relief is Non Precedent Setting

The Federal Aviation Administration has previous ly granted deviation from the requirements of §121.333(e)(2) utilizing 14 CFR §119.55. Delta was granted Operations Specifications A525, Oxygen Supply: Passenger Cabin Occupants

. See appendix 4 . In this deviation the FAA granted relief from §121.333(e)(2) for up to 20 minutes for international supplemental operations associated with Iraqi Freedom.

Conclusion

The purpose of a safety management system is to continuously identify haza rds and reduce risks to the operation and traveling public. The hazard of controlled flig ht into terrain will be reduced by granting Delta exemption from §121.333(e)(2).

In consideration of this petition based on the information contained above, Delta maintains that it is prudent for the FAA to grant Delta Air Lines an exemption to allow aircraft after a depressurization event to initially descend to 14 ,000 MSL feet then to descend to at least 10,000 feet no later than 30 minutes after the initial depressurization event without carrying the additional oxygen required by §121 .333(e)(2). The Delta proposal reduces the risk of controlled flight into terrain, provides more direct flight paths to land after a depressurization event and removes a hazardous materials risk. Delta demonstrates an equivalency based on a physiological analysis and comparison to other Federal Aviation Rules. The public interest is metPetition for Exemption - (FAR) §121.333 (e)(2) Delta Air Lines, Inc. June 6, 2011 Page 10

by the elements stated above pl us an economic and environmen tal element that demonstrates how equipage will not justify the cost and pose an additional hazard.

Summary

Delta Air Lines requests exemption to allow the aircraft after a depressurization event to initially descend to 14,000 feet then to descend to at le ast 10,000 feet no later then 30 minutes after the initial depressurization event without ca rrying the additional oxygen required by §121.333(e)(2) provided certain conditions and limit ations are met. Granting this exemption will reduce the controlled flight into terrain (CFIT) risk associated with a decompression event.

Please contact Charles M. Schr amek, General Manager Quality Assurance and Compliance, at (404) 715-1112 or e-mail at chuck.schramek@delta.com , if you have and questions or need additional information.

Sincerely,

Stephen M. Dickson Senior Vice President Flight Operations Delta Air Lines, Inc.

cc: Steve Gorman, Chief Operating Officer – Delta Air Lines Ken Hylander, Senior Vice President Corporate Safety, Security, and Compliance – Delta Air Lines Lisa Brockenbrough, Director, Flight Safety – Delta Air Lines Charles M. Schramek, General Manager Quality Assurance and Compliance – Delta Air Lines Thomas Stachiw, Office Manage r Delta Certificate Office – FAA David Gerken, Acting Office Manager Delta Certificate Management Unit– FAA James T. Giles, Jr, Principal Operations Inspector Delta Certificate Management Unit – FAAPetition for Exemption - (FAR) §121.333 (e)(2) Delta Air Lines, Inc. June 6, 2011 Page 11



### Appendix 1Petition for Exemption - (FAR) §121.333 (e)(2) Delta Air Lines, Inc. June 6, 2011 Page 12Petition for Exemption - (FAR) §121.333 (e)(2) Delta Air Lines, Inc. June 6, 2011 Page 13Petition for Exemption - (FAR) §121.333 (e)(2) Delta Air Lines, Inc. June 6, 2011 Page 14Petition for Exemption - (FAR) §121.333 (e)(2) Delta Air Lines, Inc. June 6, 2011 Page 15Petition for Exemption - (FAR) §121.333 (e)(2) Delta Air Lines, Inc. June 6, 2011 Page 16Petition for Exemption - (FAR) §121.333 (e)(2) Delta Air Lines, Inc. June 6, 2011 Page 17



### Appendix 2



## DEPRESSURIZATION EFFECTS ON COMMERCIAL AIRCRAFT

By: Dr. Allen J. Parmet

PART I – ALTITUDE PHYSIOLOGY

The basic problem of altitude change in volves the decrease in total barometric pressure as well as the partial pressure of oxygen. At sea level, barometric pressure is 14.7 PSI/760 mmHg/29.92 inHg. Note that in this paper, we will only use the metric measurements of millimeters of mercury (mmHg) as the standard used within the scientific community. The table will cont ain an equivalent pounds per square inch (PSI) notation.

Humans must have sufficient barometric pressure to k eep their blood from boiling. The atmospheric pressure drops to this level of 47 mmHg (0.9 PSI) at an altitude of 63,000 feet. At this altitude, the boiling point of water is the same as normal human body temperature or 37  ̊ C./98.6  ̊ F. This represents an absolute altitude limitation without pressurization.

Humans also require a sufficient amount of oxygen so that their body, and in particular the brain, functions. The human brain only operates aerobically; that is, it r equires oxygen for its metabolism. Other organs of the body, such as muscles, skin and bone, can function anaerobically for prolonged periods of time although the metabolism is far less efficient and result in a buildup of lactic acid. The minimum level of oxygen reaching the alveoli of the lungs for normal brain function is a pressure of 45 mmHg.

Oxygen is present at 21% of the atmosphere at all alti tudes. Thus, when the barometric pressure drops, the partial pressure of oxygen also drops while the composit ion remains constant at 21%. This permits an aircraft at altitude to compress the ambient air to a pressure sufficient for normal human function. Current commercial aircraft are limited to a cabin altitude maximally of 8,000 feet or a barometric pressu re of 565 mmHg/10.9 PSI. The partial pressure of oxygen drops from 160 mmHg at sea level to 118 mmHg at 8,000 feet. The resulting oxygen delivered to the lung, known as the PaO 2 , is 69 mmHg. The tabular representation of this is in the attached table.

Up to an altitude of 15,000 feet, there is sufficient o xygen in the ambient air for normal human operation due to the ability of the body to compensate. Compensati on is a complex function and manifested by several physiologic changes. First, the rate of respiration, or number of breaths per minute, increases as to the depth of respiration. The volume is significantly increase d as well. Our normal breath will take in only about 500 milliliters of air, but under these circ umstances a respiration co uld be increased to 800 or even 1,000 milliliters per breath and respiratory rate will clim b from 14 per minute to 20-24. This in creased rate of re spiration also results in increased exhalation of t he waste product carbon dioxide (CO 2 ). CO 2 is a weak acid and removal of this acid from the blood stream alters the blood pH fr om a normal 7.40 to as high as 7.44. While this seems slight, the change in acidity of the blood alters the hem oglobin within red blood cells and increases their ability to capture oxygen while passing through the lungs. T hus, a human has the reserve capacity to become more efficient and collect a higher percentage of oxygen from inspired air at high altitude.

If high altitude hypoxia is maintained for a longer period of time than just a few hours, the effect of the lower oxygen level on the kidneys causes the kidneys to secr ete a hormone known as erythropoietin (EPO). The EPO hormone will cause bone marrow to produce more re d blood cells, thus providing increased carrying capacity. Within 3-4 days, the blood carrying capacity can be increased as much as 5% and over several weeks, up to 10%. Individuals who live at high alti tudes will typically have blood counts 10% higher than people living at sea level. This latter is termed a chronic ad aptation. A mild effect is seen in all aircrew that spend many hours per month at altit ude and periodically experience hypoxia.Petition for Exemption - (FAR) §121.333 (e)(2) Delta Air Lines, Inc. June 6, 2011 Page 18

Under normal operating conditions, an aircraft cabin at 8,000 feet results in no physiologic changes in a normal individual and indeed, at 12,000 feet can be tolerated for an indefinite period of time in most individuals.

The rare person, about 1 in 20, when exposed to an alti tude of 12,000 feet or more for greater than 12 hours can begin to develop illnesse s called high altitude pulmonary edema (H APE) and high altitude cerebral edema (HACE). These are treated by descent. The nature of physiologic adaptation is easily demonstrated by mountain climbers who are able to climb Mount Everest (29,029 feet) without suppl emental oxygen by using the physiologic adaptation process over a period of weeks. Even so, at that extreme altitude, they do so under a condition of marked physiologic compromise.

PART II – RESPIRATORY COMPROMISE IN PASSENGERS

The American Thoracic Society describes characteri stics of individuals who hav e developed pulmonary and respiratory compromise as Respiratory Class I, II, III and IV based upon certain standards, with Class I being the least serious and Class IV being the worst. Any disease such as emphysema, fibrosis or trauma may destroy so much lung function that an individual is no longer considered to be normal based upon the objective
measurements.

A Class I individual, however, is able to function normally and perform all their activities although at a reduced level. Class II individuals will become short of breath with minimal physical exerti on. They generally become significantly short of breath climbing a flight of stairs or walking 50 fee t. Class III individuals will be short of breath even at rest and may require supplemental oxygen fo r normal activity. Class IV individuals are severely compromised and require supplemental oxygen to maintain life.

Supplemental oxygen consists of increasing the percentage of oxygen in the inspired air. The percentage of oxygen in the atmosphere is as noted above, 21% at a ll altitudes. The term for fraction of inspired oxygen percentage is FIO 2 . Most supplemental oxygen is delivered by a device known as a nasal cannula, which is a tube ending in two short prongs with one going into each nostril. A nasal cannula can deliver supplemental oxygen up to about 36%, which requires a flow of approxim ately 8.0 L/min. Even at this level, a nasal cannula is quite compromised and very uncomfortable to wear. It is rarely used at flows above 4.0 L/min, which can deliver an FIO 2 of 28%. When the FIO 2 required is between 28 and 40%, then a mask is used. These breathing masks will have apertures in them that per mit mixing of ambient air. To achieve an FIO 2 of greater than 40%, a close-fitting, sealed mask, typically termed “aviator’s mask”, must be used. However, an FIO 2 of greater than 40% will create the risk of oxygen toxicity. T he results are an injury to the lungs caused simply by the high levels of oxygen and free radical formation. Therefore, individuals cannot generally be maintained on a high FIO 2 indefinitely and such levels are in general only used for hospitalized patients.

The issue of high FIO 2 in aircrew would be true except for the fact that the barometric pressure drops, resulting in an absolute level of oxygen, that is the partial pressu re, is the equivalent of sea level pressure and therefore toxicity is not an issue in aviation, even when breathing 100%.

PART III – DECOMPRESSION EVENTS

If a commercial aircraft is operating at an altitude betwe en 33,000 feet and 42,000 feet with a cabin pressure of 8,000 feet above sea level, the pas sengers will not experience any physiologic compromise. If loss of cabin pressurization occurs, however, the barometric pressure drops to ambient and the partial pressure of oxygen drops to the point that the ability of an individual to f unction, known as the Time of Useful Consciousness or Effective Performance Time, becomes only a few seconds. Therefore, supplemental oxygen is imperative. Aircrew are equipped with quick-donned aviators masks ca pable of delivering 100% oxygen. At an altitude of 33,000 feet, 100% oxygen becomes physiologically equivalent to breathing normal air at sea level. This is to say that the barometric pressure at 33,000 feet is effect ively the same as the partial pressure of oxygen at sea level. Above this altitude, less and less oxygen be comes available to the br ain even though supplementalPetition for Exemption - (FAR) §121.333 (e)(2) Delta Air Lines, Inc. June 6, 2011 Page 19

oxygen up to 100% is used. Therefore, descent to a safer al titude is critical. However, it is most critical that the aircraft be flown in a safe manner and not strike terra in. Remaining at a safe altitude is more imperative than supplying oxygen to passengers.

Supplemental oxygen is available to passengers through two methods. Most common is the chemical oxygen generator. This canister is installed in the ov erhead compartment in virtually all commercial aircraft. These canisters, such as those manufa ctured by AVOX Systems or older sy stems by Puritan Bennett, contain a super-oxide chemical. An igniter pin triggers a reacti on and the chemical combusts, burning like a solid rocket motor. However, the combustion products are typically salts (NaCl or KCl) and o xygen. These canisters can produce the equivalent of 7.0 L/min of oxygen flow for the first 3-4 minut es and then an additional 3 L/min of oxygen flow for 12-15 minutes (Puritan Bennett an d some AVOX models). Other models have lower peak flows at 3.6 L/min for the first 4-6 minutes and then an additional 0.8 L/min of oxygen flow for 10 minutes (Lockheed AVOX).

This means that at the initial 7.0 L/min flow, the pressure is approximately 180 mmHg and at 3.6 L/min, it is 92 mmHg. If the initial flow is 3 L/min, then it is appro ximately 75 mmHg and at 0.8 L/min it is 20 mmHg. This pressure represents oxygen added to the ambient air and displaces the ambient air. The mask used to deliver this, a small yellow mask typically ca lled a “margarine cup”, when placed on the face will provide a reasonably good seal. A flap valve permits mixing of cabin air with the supplemental oxygen if the ambient pressure is higher than the mask pressure.

Thus, at the high flow of 7.0 L/min when the cabin al titude is above 35,000 feet, there will be little or no ambient air mixed in, and the user will effectively be on 100% oxygen. The passenger is physiologically at sea level. If the flow is 3.6 L/min, with the ambient pressure at about 197 mmHg, the FIO 2 is approximately 60%. This is equivalent to a real pressure altitude of 8,000 feet.

At lower altitudes, cabin air will begin to mix and by an al titude of 18,000 feet where the barometric pressure is 380 mm and at a 3.0 L/min flow will be approximately 65 mmHg. The mixed gas inspired will be approximately 38% oxygen. If the flow is 0.8 L/min, then the mixed gas will have an FIO 2 of approximately 25%. This is equivalent to a real pressure altitude of 14,000.

The use of the emergency mask will be unnecessary below 15,000 feet although passengers may continue to use this until the generator is empty. When the flow stop s, the flap valve permits cabin air to enter the mask without mixing and minimal resistance, so even an unconscious person would not asphyxiate.

For individuals with compromised pulmonary function, the emergency use of a ch emical oxygen generator therefore provides a high enough oxygen flow to be equival ent to any supplemental oxygen they could legally use to fly as a passenger. However, when a generat or drops to the lower fl ow, hypoxia will ensue and eventually with the generator emptying after 15-18 minutes, these individuals will either need to resume using their own supplemental oxygen or be augmented by o xygen provided from the emergen cy supply by the flight crew. With supplemental oxygen, these individuals will function nearly normal, but compromise would be anticipated. Without supplementa l oxygen, a compromised individual would be expected to lose consciousness. However, death does not ensue in resp iratory compromised individuals except in the most fragile of all cases. These individuals may have been ta king excessive risk in their choice to travel by commercial air rather than air ambulance, and it will be impossible to provide for all individuals under all circumstances, in particular a class III respiratory individual who has assured the transporting ai rline that they were class II or less.Petition for Exemption - (FAR) §121.333 (e)(2) Delta Air Lines, Inc. June 6, 2011 Page 20

RESPIRATORY FUNCTI ON AT ALTITUDE WITH THE ADDITION OF SUPPLEMENTA L OXYGEN AT HIGHER ALTITUDES

Altitude Barometric Pressure (P B ) Partial Pressure of Oxygen (PO 2 ) Arterial Oxygen Level (PaO 2 ) Time of Useful Consciousness Sea Level FIO 2 21% 14.7 PSI/ 760 mmHg 160 mmHg 103 mmHg Indefinite

8,000’ 10.9 PSI/ 565 mmHg 118 mmHg 69 mmHg Indefinite

10,000’ 10.1 PSI/ 522 mmHg 109 mmHg 61 mmHg Indefinite

12,000’ 9.3 PSI/ 483 mmHg 101 mmHg 54 mmHg Indefinite

14,000’ 8.6 PSI/ 446 mmHg 93 mmHg 48 mmHg Indefinite

18,000’ FIO 2 21% 7.35 PSI/ 380 mmHg 80 mmHg 38 mmHg 30 minutes

18,000’ FIO 2 25% 7.35 PSI/ 380 mmHg 95 mmHg 50 mmHg Indefinite

33,000’ FIO 2 21% 3.81 PSI/ 197 mmHg 40 mmHg 23 mmHg 45 seconds

33,000’ FIO 2 36% “ “ 71 mmHg 40 mmHg 15 minutes

33,000’ FIO 2 60% “ “ 118 mmHg 69 mmHg Indefinite

33,000’ FIO 2 100% “ “ 197 mmHg 109 mmHg Indefinite

42,000’ FIO 2 21% 2.48 PSI/ 128 mmHg 27 mmHg 8 mmHg 10 seconds

42,000’ FIO 2 36% “ “ 46 mmHg 15 mmHg Approximately 15 seconds 42,000’ FIO 2 100% “ “ 128 mmHg 41 mmHg IndefinitePetition for Exemption - (FAR) §121.333 (e)(2) Delta Air Lines, Inc. June 6, 2011 Page 21



### Appendix 3



### EASA RulePetition for Exemption - (FAR) §121.333 (e)(2) Delta Air Lines, Inc. June 6, 2011 Page 22



### Appendix 4