AFS

- 14

- 285

- E Exemption No. 11613

UNITED STATES OF AMERICA

DEPARTMENT OF TRANSPORTATION

FEDERAL AVIATION ADMINISTRATION WASHINGTON, DC 20591

In the matter of the petition of

SPRINGFIELD AIRCRAFT Regulatory Docket No. FAA

- 2014

- 0315 CHARTER AND SALES, INC.

for an exemption from § 135.89(b)(3) of Title 14, Code of Federal Regulations

DENIAL OF EXEMPTION

By letter dated May 14, 2014, Mr. Louie DeSantis, Assistant Director of Operations, Springfield Aircraft Charter and Sales, Inc., ( Springfield Aircraft ), 10 Nor thwest Richards Road, Suite 108, Kansas City, MO 6411 6, petitioned the Federal Aviation Administration (FAA) on behalf of Springfield Aircraft for an exemption from § 135.89(b)(3) of Title 14, Code of Federal Regulations (14 CFR). The proposed exemption, if granted, would allow Springfield Aircraft to o pera te a pressurized aircraft at altitudes above 35,000 feet mean sea level (MSL) , [FL350], without requiring the pilot at the controls to wear, secured and sealed, an oxygen mask.

The petitioner requests relie f from the following regulation :

Section 135.89 (b)(3) p rescribes , in pertinent part, that “Whenever a pressurized aircraft is operated at altitude s above 35,000 feet MSL, at least one pilot at the controls shall wear, secured and sealed, an oxygen mask...”

The petitioner supports its request with the f ollowing information:

The petitioner states that

, by operat ing under §121.333 (c)(2)(i)(A) instead o f § 135.89(b)(3) , it

wou l d realize significant savings in on

- board oxygen duration, thereby enhancing operational safety when conducting extended over water /remote missions. Th e petitioner contends that

th is reduction in en route oxygen use is paramount when flight planning extended operations2

over remote and/or oceanic areas by increasing the amount of available oxygen at the Equal Time Point (ETP) for cabin depressurization emergencies.

The petitioner states that

, in some cases, the ability to remain at FL250 for extended perio ds of time post loss of cabin pressure is mandatory to prevent incurring a “ wet footprint ” or for terrain clearance requirements in areas of exceedingly high terrain.

The petitioner states its current aircraft fleet is s uch that aircraft system oxygen is available to all crew/passengers and the passenger masks are approved for continuous use up to FL250. Because of this capability, th e petitioner states it is able to improve overall safety by descending to FL250 (initially) during an aircraft depressurization, rather than a continuous descent to 10,000 feet. According to the petitioner, t his strategy serves two purposes:

1) Enhanced ter

rain separation clearance

– The petitioner states that there are few geographic areas around the world that would penet rate the FL250 capability of its

aircraft. By limiting the initial descent during a depressurization to FL250, the crew is able to regrou p and evaluate terrain/obstacle clearance before commencing further

descent.

2) Extended ETP envelope

– The petitioner suggests that m ost part 121 air c arriers plan a descent to FL100 after experiencing a depressurization, incurring huge penalties in en

rout e fuel flow and a drastic increase in diversion times as a result. Additionally, when conducting oceanic or remote operations, the aircraft is now limited in diversion capability due to the low altitude, high fuel flow, and resultant low true airspeed.

Con versely, the petitioner states, its aircraft are able to level at FL250, above significant terrain and weather, and hold higher Mach/true airspeed, thereby reducing diversion times to the alternate airport. The petitioner asserts that the relief from §135. 89(b)(3) delays, for a short period, the onset of single crewmember oxygen depletion while manning the flight deck. The petitioner asserts that p art 121 aircraft operate predominantly between FL 330

- 370, whereas corporate aircraft are designed to

start cru ise at FL390 to FL410 and continue optimized climb schedules to as high as

FL510.

The petitioner states that few corporate aircraft can make designed range profiles below FL410, its fleet included. The petitioner points out that the G ulfstream V’s (GV) Q u ick

R eference H andbook flight planning chart starts at FL390 and continues up to FL490. The petitioner states the difference in hourly fuel burn betw een FL350 and FL450 i s almost 1,000 pounds per hour and that, over a typical 10

- 12 hour flight

, altitude pl ays an important role in efficiency and range.

The petitioner states that , by its analysis, a mid

- size, mid

- range, corporate aircraft conducting a flight from SFO

- HNL with six passengers and two crew (oceanic/remote operations) close

to the limits the air craft, cannot, under most circumstances, descend to FL100 after a depressurization and make land with the required reserves, i.e., incurring a wet footprint.3

Under this scenario, once reaching FL100, the aircraft must slow to max range cruise just to

make land taking roughly 3+51. However, by stopping descent at FL250 to expend on board oxygen (120 minutes), then commencing descent to 10,000 feet the aircraft easily makes land over 1.7 hours sooner, at roughly 2+10. The petitioner concludes that r educing cr ew and passenger exposure to extended diversion times during emergency situations is paramount to a successful (and survivable) outcome to an emergency.

The petitioner states the significance of this scenario is the fact that prior to reaching FL410,

upon passing FL350, at least one crewmember must be depleting the oxygen system. Under the above scenario, the oxygen reserve (fully serviced bottle) at FL250 is approximately 161 minutes (3140 liters of O 2 ), minus what the crew consumes prior to the

ETP. To prevent a wet footprint scenario, the aircraft must arrive at the ETP with approximately 2,640 liters of oxygen (120 minutes at FL250 for two crew members and six

passengers ). Estimating an average consumption rate of 3 liters/min (per single crew member at a typical pressurized cabin altitude) for the 146 minutes it takes to arrive at the ETP

, 438 liters of available oxygen would be depleted

, l eaving roughly 2702 liters of oxygen remaining (3140 liters of fully serviced O 2 system). This leaves a differenc e of only 62 liters of oxygen. Keep in mind that these numbers are based on a fully serviced bottle at 1800 pounds per square inch

.

The petitioner state s that where relief from §135.89(b)(3) will come into play is by delaying the depletion of oxygen until reaching higher flight leve ls (above FL410 ). In this case, they would expect to be above FL350, but below FL410, for approximately 30 minutes, thereby

savin g roughly 90 liters of oxygen. The petitioner asserts that, for longer

- range missions in the GV, wh ere initial level off altitudes at high gross weights are below FL410 for several hours,

it could realize savings of roughly 300 to 500 liters of oxygen. This is a significant factor in mitigating compound emergencies and reducing risk to those on board. B y complying with §121.333 (c)(2)(i)(A), flight crews will be better prepared to deal with a loss of cabin pressure by having the maximum amount of available oxygen when it is needed the most ; to execute a rapid descent to a safe altitude and extend diversi on cruise capability at a higher altitude.

The petitioner emphasizes that both fleet aircraft types it currently operates include an automatic Emergency Descent Mode designed to augment/protect the initiation of an emergency descent should the crew beco me incapacitated. Both the GV and Cessna

Citation X ( CE750 ) , with autopi lot engaged, will initiate a 90 degree left turn, descending at maximum operating limit speed ( Vmo/Mmo ) to 15,000 feet and level off.

The petitioner states that it is important to not e the redundancy built into both the GV and CE750 pressurization systems, which are certified under part 25 (Airworthiness Standards: Transport Category Aircraft)

. The petitioner describes the redundancies as follows:

 Both aircraft have two sources of en gine bleed air, either of which is sufficient to meet the demands of the aircraft. Additionally, both aircraft are equipped with dual air conditioning packs, each of which is capable of supplying sufficient pressurization air4

in the event one unit fails. B oth aircraft are equipped with an isolation valve that will allow one engine to supply bleed air to both packs in the event of an engine failure, bleed leak, or other cause for single source bleed supply. Both aircraft are equipped with dual pressure vesse l bulkheads between the cabin and baggage compartments. If the baggage door seal were to fail, the secondary pressure vessel and check valves automatically isolate the baggage compartment and maintain normal cabin pressure.

 Both aircraft pressurization c ontrollers are triple redundant with an automatic, manual, and emergency mode of control that are supplied power f rom multiple redundant

sources. In terms of warning systems available to advise the flight crew of impending failure or increasing cabin altit ude both aircraft are equipped with multiple set points for both warning and caution messaging, including aural advisories.

 The passenger oxygen system automatically deploys at approximately 13,500 feet, and above a cabin altitude of FL370, crew oxygen ma sks automatically provide pressure breathing rather than just 100 percent oxygen.

The petitioner contends that, a s a result of the multiple levels of redundancy in the pressurization system, one of the only means of a truly “rapid” or “explosive” decompre ssion would be a significant structural failure of a cabin door, cabin or cockpit window, or failure the aluminum skin structure or ribbing. The petitioner states that, t o date, there has never been

such a failure on either aircraft since their certificati on in the late 19 90’s.

The petitioner points out that its fleet is equipped with T echnical S tandard Order (C78a, C89a, C99a) quick donning on

- demand oxygen masks of the same make/model as those used in
part 121 air carrier operations

. T he petitioner state s that the same operating procedures for both oxygen masks are employed. Furthermore, the petitioner contends that these systems are certified under § § 25.1441 through 25. 1 453, the same regulations part 121 air c arrier aircraft are manufactured thereby pos itively establishing equivalent levels of safety.

The petitioner states that it seeks relief from § 135.89(b)(3) not as a means to circumvent regulations but, r ather

, because it has been deemed vital to flight safety to mitigate oxygen depletion to conse rve emergency oxygen reserves in the event an aircraft experiences a loss of cabin pressure and is forced to descend to lower altitudes.

The FAA’s analysis:

The FAA has fully considered the petitioner’s supporting information. The FAA has

determined tha t the circumstances the petitioner presents do not justify a grant of exemption. The FAA finds that the petitioner has not shown how a grant of exemption would be in the public interest or how it would provide a level of safety equivalent to that provided under the current regulation. Our analysis is based on the lack of safety mitigations put forth by the petitioner

, such as the extent and type of training crew members receive on high altitude operations

, to include the effects of hypoxia

, the procedures that crew members must follow5

prior to reaching FL350, and the procedures that address crew members ’ actions when operating above FL350. We determined the failure to address these concerns overlook s the purpose f or requiring at least one pilot at the contr ols to wear an oxygen mask as required by § 135.89(b)(2)(i).

In a decompression event, the pilot’s judgment and motor skills may become impaired almost immediately. Because of the possibility of impairment, the proposed exemption poses an unacceptable risk to the safety of flight

. In gradual decompression situations, crewmembers may fail to recognize the effects of hypoxia and a single pilot not wearing an oxygen mask may not be able to don the mask due to the effects of hypoxia. The FAA referred to th e National Transportation Safety Board ( NTSB ) accident report ( CHI96IA157 ) that involved American Trans Air, F light 406

, on May 26, 1996, as an example of the dangers of hypoxia.

A lso see William F. O’Conner, Ph.D. and George E. Pendergrass, Effects of De compression on Operator Performance , DOT/FAAAM 66

- 10 on page 6, which evaluates decompression impairment and its affects, conclud ing that “T he various analyses indicate impairment of the operator’s rate of performance for 2 to 4 minutes following rapid dec ompression with some suggestion that the severity of effects increases with increase in decompression altitude

. T he operator’s total time lost from his primary task, at the point of decompression where donning is required, has a mean value of some 16 seco nds, while the 95th percentile falls at about

25 seconds

. ” In Reactions and Performance of Pilots Following Decompression, Aerospace

Medicine 32

, pages 134 to 136

, G. Bennett stated that only 36 percent of pilots were able to

don their masks within 10 sec onds following a decompression at 30,000 feet. In addition, it

was found that all subjects reported hypoxia symptoms

, and finally conclud ed that full protection at 40,000 feet could not be guaranteed unless pilots were wearing their masks and breathing oxy gen at the time of decompression.

The petitioner asserts that given the advances in technology, a rapid decompression event would be very rare, and even in the case of such an event

, the mask could be easily donned by the crewmembers. However, the FAA no tes that relative to the potential likelihood of a decompression, the Transport Aircraft Directorate (TAD) has developed mathematical decompression models for aircraft certification. According to the TAD, an engine rotor burst event could cause a very rap id decompression, even in a large volume aircraft. Although s uch

an event is rare

, the TAD cannot classify the event as “extremely improbable.” In the case of such an event, nevertheless , a crewmember must be able to respond quickly and to ensure

such re sponse, it is necessary for the crewmember to comply with § 135.89.

On August 12, 1982, the FAA published Notice of Proposed Rulemaking (NPRM)

No. 82

- 11, Pilot Oxygen Mask Requirements (47 FR 35146) that proposed amendments to pertinent sections of p arts 91, 121 and 135 pertaining to flightcrew oxygen mask use requirements. The proposed amendments would allow the operation of aircraft to higher altitudes than presently specified in the regulation without requiring at least one pilot at the

controls to wea r and use an oxygen mask . The NPRM was premised on several

considerations : ( 1) the capabilities and limitations of oxygen equipment; (2) pressure vessel size and probabilities of depressurization; (3) operational limitations at the maximum6

altitudes of mo dern aircraft; and (4) perceived inequity in the applicabi lity of oxygen requirements in p art 135 compared to those in p art 91

. It was noted in the NPRM that the proposed amendments, if adopted, would be responsive to industry petitions for exemption

and alleviate, to some extent, certain burdens perceived by aircraft operators that restrict the ease and flexibility of flight operations. Coincidentally, the FAA would be relieved from the administrative burden of granting exemptions to the regulation

.

The concerns expressed by certain commenters opposed to the p roposed amendments

contained in Notice No. 82

- 11 prompted the FAA to reconsider the proposed amendments and the supporting rationale included therein and also stated in previous grants of exemption. Particular attention was directed at the potentially severe physiological consequences resulting from high altitude depressurization in both large and small cabin volume aircraft that possibly would incapacitate the flightcrew and result in an accident. That reconsideration led the FAA to conclusions different from those expressed in Notice

No. 82

- 11 and previous grants of exemption. The FAA determined that further grants of exemption should be discontinued and the notice withdrawn. Notice No. 82

- 11 was withdrawn March 18, 1986 (51 FR 9432) and incorporated by reference in this analysis/summary.

Further, the F AA subsequently e v a lu a t e d the t y pe of op era tions th a t y

ou p r opos e

. I

n D e ni a l of

E x e mption No s . 4667 and 8502 (c op ies e n c los e d ) , the F AA cited th a t it publish e d the

withdrawal of Noti c e of P r opos e d R ul e m a king ( N PR M) No. 82

- 11, P ilot O x y g e n M a sk

R e qui re m e nts ( 47 F R 35146 ). The F AA f u r th e r d e t er min e d th a t if it f ound th a t it c ould

g ra nt re li e f fr om the c u rre nt re g ul a tion, it would initi a te a r ul e m a kin g ac tion ra th e r th a t
issue g ra nts of e x e mption.

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 Springfield Aircraft Charter and Sales, Inc. for an exemption from 14 CFR § 135.89(b)(3) is hereby denied.

Issued in Washington, D

. C

. , on May 18, 2015.

.

/s/ John S. Duncan Director, Flight Standards Service