Docket Management Facility
U.S. Department of Transportation
400 Seventh Street, SW
Nassif Building
Room PL-401
Washington, DC 20590

Attention: Docket No. FAA-2005-229 15; Amendment No. 121-317

Dear Sir or Madam:

The National Transportation Safety Board has reviewed your direct final rule, titled “14 [Code of Federal Regulations] CFR Part 121 Supplemental Oxygen,” which was published in 70 Federal Register, 68330-68333 on November 10, 2005. The direct final rule proposes to amend the Federal Aviation Administration’s (FAA) regulation on the use of pilot supplemental oxygen. The amendment of 14 CFR 121.333 changes the flight level (FL) at which the remaining pilot at the controls of the airplane must put on and use his oxygen mask if the other pilot at my time leaves his control station of the airplane. This amendment revises that altitude from “above flight level 250” to “above flight level 350.”


In its rationale for the amendment, the FAA cites time of useful consciousness (TUC) data indicating a mean TUC at FL 350 of 34 seconds and a minimum observed TUC at FL 350 of 17 seconds. The Safety Board has previously identified these TUC data as inaccurate because they are based on older studies involving very simplistic task performance and are not representative of the actual cognitive demands placed on pilots under decompression situations. For example, following the investigation of the October 25, 1999, accident involving a Sunjet Aviation Lear 35 that crashed near Aberdeen, South Dakota, the Safety Board issued Safety Recommendation A-00-109 asking the FAA to “revise existing guidance and information about high-altitude operations to accurately reflect the time of useful consciousness and rate of performance degradation following decompression and to highlight the effect of hypoxia on an individual’s ability to perform complex tasks in a changing environment..." The recommendation is currently classified, “Open-Unacceptable Response.”

According to supplementary information contained in this direct final rule, “the FAA believes that in actual aircraft operations, the single pilot may be delayed, and take longer than 5 seconds to start inhaling supplemental oxygen. Any such delay will take up part of the TUC.” In recognition of this potential delay, the Safety Board is concerned that the proposed amendment does not provide an effective margin of safety for these operations if TUC data that more accurately reflect the task demands associated with a decompression event are used. For example, studies indicate that at an altitude of 30,000 feet, rapid decompression has been shown to decrease by nearly 25 percent the amount of oxygen available in the blood within 8 seconds. (1)

Because the FAA relied on TUC data that do not represent actual pilot performance under realistic decompression conditions, the FAA’s proposed change to 14 CFR 121.333 would have an adverse affect on aviation safety. Accordingly, the Safety Board does not support this proposed amendment and asks the FAA to publish a notice in the Federal Register, withdrawing the direct final rule before it becomes effective.


Sincerely,


Original Signed by


Mark V. Rosenker
Acting Chairman







(1) See H. Marotte, C. Toure, J.M. Clere, and H. Vieillefond. 1990. “Rapid Decompression of a Transporf Aircraft Cabin: Protection Against Hypoxia.” Aviation Space and Environmental Medicine 61: 21 -27.

[4910-13]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 121

Docket No.: FAA-2005-22915; Amendment No. 121-322

RIN 2120-ai65

Supplemental Oxygen

AGENCY: Federal Aviation Administration, DOT.

ACTION: Direct final rule; withdrawal.

SUMMARY: On November 10, 2005, the Federal Aviation Administration (FAA) published a direct final rule to amend its regulation on the use of supplemental oxygen with an effective date of January 9, 2006. The FAA received and adverse comment from the National Transportation Safety Board stating that the FAA relied on time of useful consciousness data that did not represent actual pilot performance under realistic decompression conditions. In accordance with § 11.31, which states if the FAA receives an adverse comment it will notify the public by publishing a document in the Federal Register, the FAA is using this notice to withdraw this direct final rule in whole.

DATES: The direct final rule published at 70 FR 68330, Nov 10, 2005 is withdrawn effective January 6, 2006.

FOR FURTHER INFORMATION CONTACT: Timothy Adams, Airmen and Airspace Rules Division (ARM-100), Office of Rulemaking, Federal Aviation Administration, 800 Independence SW., Washington, DC 20591; Telephone No. (202) 267-9680.

List of Subjects

14 CFR Part 121

Air carriers, Aircraft, Aviation Safety, Reporting and recordkeeping requirements, Safety, Transportation.

The Amendment

In consideration of the foregoing, the Federal Aviation Administration withdraws the direct final rule published at 70 FR 68330 on November 10, 2005.


Issued in Washington, DC on JAN 03 2006


Marion C. Blakey