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Petition for Amendment to Exemption No. 8668 which permits relief from 14 

CFR 25.1447(c)(1) Amendment 25-41

Name and Address of the Petitioner

Douglas Lane, Deputy Lead Administrator

The Boeing Company

PO Box 3707, M/S 03-56

Seattle, Washington, 98124

Section(s) of the Regulation(s) to which an Amendment is sought:

Section 25.1447(c)(1), as amended by Amendment 25-41, states that there must be 

an oxygen dispensing unit connected to oxygen supply terminals immediately 

available to each occupant, wherever seated. If certification for operation above 

30,000 feet is requested, the dispensing units providing the required oxygen flow 

must be automatically presented to the occupants before the cabin pressure altitude 

exceeds 15,000 feet and the crew must be provided with a manual means to make 

the dispensing units immediately available in the event of failure of the automatic 

system.

Extent of Amendment Sought and Reason(s)

Based on below justification and the precedent set on Boeing Models 737-600/-700/-

800/-900, Boeing requests adding Boeing Models 737-7/-8/-9/-900ER to existing

Exemption No. 8668 from the requirement of 14 CFR 25.1447(c)(1) to permit 

passenger oxygen masks to be automatically presented at cabin pressure altitude of 

15,650 feet when operating into airports with altitude above 9,500 feet and below 

14,500 feet.

Description of Issue

For operations into airports between 9,500 feet and 14,500 feet, the aircraft will be 

equipped with a high altitude landing switch. This switch controls when the cabin 

altitude warning horn will sound and also when the passenger oxygen masks will be 

deployed.

For operations into and out of airports below 9,500 feet, the high altitude landing 

switch remains in the “INOP” position with the cabin altitude warning at 10,000 feet 

and the oxygen masks deployment setting of 14,650 feet. 

For operations into airports above 9,500 feet, the high altitude landing switch is 

positioned to “ON” and initial descent or approximately 20 minutes prior to landing. 
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The cabin altitude warning changes from 10,000 feet to 15,200 feet. The oxygen 

mask deployment setting changes from 14,650 feet to 15,650 feet.

When departing an airport above 9,500 feet, the high altitude landing switch is 

positioned to the “INOP” position. The cabin altitude warning is set at 10,000 feet 

and the oxygen mask deployment set at 14,650 feet. The oxygen system 

architecture is designed so that as long as the aircraft is on the ground the oxygen 

masks will not automatically deploy. The cabin altitude warning is latched and will 

not switch from 15,200 feet to 10,000 feet until the cabin is pressurized below 

10,000 feet.

An individual light on the high altitude landing switch is illuminated when it is in the 

“ON” position so that the crew is reminded to reset the switch prior to departure from 

high altitude airports. The indication light turns off after the switch is reset. Even if 

the altitude at which the masks will automatically deploy is set at 15,650 feet instead 

of 14,650 feet, the flightcrew can manually deploy the masks at any time.

The 737 high altitude landing switch functions the same as other Boeing models.

Automatic activation of the oxygen system is transparent to the flightcrew. There are 

no additional oxygen tasks in the Airplane Flight Manual (AFM) or Flight Crew 

Operations Manual (FCM) other than what exists today. This avoids the possibility 

of flightcrew confusion. The oxygen switch point is always 14,650 feet except for the 

last 20 minutes of inbound only flights to airports above 9,500 feet elevation. Should 

a decompression occur in the last 20 minutes of flight when the oxygen set point is 

15,650 feet there will be an automatic activation time delay of less than 5 seconds. 

This is the additional time necessary for cabin pressure to decrease from 14,650 feet 

to 15,650 feet. Of the 13,017 commercial jet transport airports, there are only 21 

that are above 9,500 feet in elevation, so the probability of passengers being 

exposed to an altitude above 15,000 feet is quite low.

Statement of Public Interest

Granting this exemption would be in the public interest by allowing airlines that 

operate 737 series aircraft to compete with other operators of airplanes at high 

altitude airports already approved by other authorities. Service could be provided to 

the flying public at airports with altitudes up to 14,500 feet.

Statement of No Adverse Effect on Safety

To provide operation at high attitude airports up to 14,500 feet, the Boeing Model 

737-7/-8/-9/-900ER series aircraft will be modified to install a second cabin pressure 

altitude switch. This modification would prevent nuisance deployment of the 

passenger oxygen masks at a cabin pressure altitude below 15,650 feet. Even if the 
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setting is for 16,000 feet maximum instead of 15,000 feet maximum for automatic 

oxygen mask deployment during failure of the Cabin Pressure Control System, the 

flight crew can manually deploy the masks to the passengers if necessary. Thus, if 

passengers require oxygen, the flight crew can provide oxygen manually by over 

riding the automatic system. 

Summary to be Published in the Federal Register

PETITIONER: Boeing Commercial Airplanes

SECTION OF 14 CFR AFFECTED: 14 CFR 25.1447(c)(1)

DESCRIPTION OF RELIEF SOUGHT: Exemption to permit relief from the 

requirement for passenger oxygen masks to be automatically presented before the 

cabin pressure altitude exceeds 15,000 feet for the Boeing Model 737-7/-8/-9/-

900ER series airplanes. In order to provide operation into high altitude airports up to 

14,500 feet, the Boeing Model 737-7/-8/-9/-900ER series airplanes will be modified 

to install a second cabin pressure altitude switch. This modification would prevent 

nuisance deployment of the passenger oxygen masks at a cabin pressure altitude 

below 15,650 +/-350 feet.

Request to “Waive Publication and Comment”

The petitioner would like to request waiving the requirement for Federal Register 

publication because the exemption, if granted, would not set a precedent. This is 

not a new exemption but rather a revision to an existing one (Boeing Exemption # 

8668) to add additional model series aircraft. Three similar exemptions have been 

issued: 

(1) Boeing, Exemption # 6076. A summary of Boeing’s petition was published in the 

Federal Register on February 17, 1995 (60 FR 9422). No comments were received. 

(2) Airbus, Exemption # 6994. The Airbus petition was granted September 6, 1999, 

without a public comment period, citing similarity to the Boeing exemption granted in 

1995.

(3) Boeing, Exemption # 8668. Boeing’s petition was granted December 2, 2005, 

without a public comment period, citing that the exemption does not set a precedent, 

and any delay would be detrimental to The Boeing Company. 

Privileges of the Exemption Outside of the United States 

The petitioner would like to extend the privilege of the exemption outside of the 

United States. Airports operating above 9500 feet are primarily outside of the United 

States. The majority of these airports are located in an around the Tibetan plateau.