2004_美国_AAR0402.pdf

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Collision With Trees on Final Approach Federal Express Flight 1478 Boeing 727-232, N497FE Tallahassee, Florida July 26, 2002

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Aircraft Accident Report

NTSB/AAR-04/02

PB2004-910402

Notation 7501B

National Transportation Safety Board Washington, D.C.

THE CORRECTIONS BELOW ARE INCLUDING IN THIS VERSION OF THE PUBLISHED REPORT

AIRCRAFT ACCIDENT REPORT NTSB/AAR-04/02 (PB2004-910402)

Collision With Trees on Final Approach Federal Express Flight 1478 Boeing 727-232, N497FE Tallahassee, Florida July 26, 2002

● Pages iii and iv of the Table of Contents has been updated with the correct page numbers. Corrections are noted in the table below.

Aircraft Accident Report

Collision With Trees on Final Approach Federal Express Flight 1478 Boeing 727-232, N497FE Tallahassee, Florida July 26, 2002

NTSB/AAR-04/02 PB2004-910402 Notation 7501B Adopted June 8, 200

〔图〕NATIONAL TRANSPORTATION\n National Transportation Safety Board 490 L'Enfant Plaza, S.W. Washington, D.C. 20594

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Contents

Abbreviations .................................................................... vi

Executive Summary iX

1. Factual Information .................................................................... 1

1. 1 History of Flight $\ldots$ 1

1. 2 Injuries to Persons. $\ldots$ 11

1. 3 Damage to Aircraft $\ldots$ 11

1. 4 Other Damage $\ldots$ 11

1. 5 Personnel Information. $\ldots$ 11

1. 5.1 The Captain $\ldots$ 13

1. 5.2 The First Officer. $\ldots$ 15

1. 5.3 The Flight Engineer $\ldots$ 17

1. 6 Airplane Information $\ldots$ 18

1. 7 Meteorological Information. $\ldots$ 18

1. 8 Aids to Navigation 20

1. 9 Communications $\ldots$ 20

1. 10 Airport Information. $\ldots$ 20

1. 10.1 Airport/Approach Charts 22

1. 10.2 Runway 9 Lighting. $\ldots$ 22

1. 11 Flight Recorders .................................................................................................................................................................... 26

1. 11.1 Cockpit Voice Recorder. 26

1. 11.2 Flight Data Recorder 27

1. 12 Wreckage Recovery and Documentation Information .................................................................... 27

1. 13 Medical and Pathological Information .................................................................................................................................... 30

1. 13.1 Toxicological Information $\ldots$ 30

1. 13.2 First Officer's Color Vision Deficiency. $\ldots$ 30

1. 13.3 First Officer's Postaccident Hospitalization Information $\ldots$ 38

1. 14 Fire/Explosion .................................................................................................................................. 39

1. 15 Survival Aspects 39

1. 16 Tests and Research .................................................................................................................................. 39

1. 17 Operational and Management Information .................................................................................................... 39

1. 17.1 FedEx Flight Crew Training—General 40

1. 17.2 Postaccident FedEx Actions $\ldots$ 47

1. 18 Additional Information ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

1. 18.1 Hypoxia-Related Information .................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

1. 18.2 DOT Operator Fatigue Management Program. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1. 18.3 Crew Familiarity/Attention/Monitoring Information. 49

1. 18.4 Previously Issued Safety Recommendations $\ldots$ 51

1. Analysis $\ldots$ 53

1. 1 General $\ldots$ 53

1. 2 The Accident Approach $\ldots$ 54

1. 3 Fatigue $\ldots$ 56

1. 3.1 Role of Fatigue—Captain. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

1. 3.2 Role of Fatigue—First Officer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

1. 3.3 Role of Fatigue—Flight Engineer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

1. 3.4 Fatigue Management Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

1. 4 Physiological Issues That May Have Affected the First Officer’s Performance . . . . . . 60

1. 4.1 The First Officer’s Color Vision Deficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

1. 4.2 The First Officer’s Breathing Rate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

1. 5 Crew Coordination/Monitoring Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

1. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

1. 1 Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

1. 2 Probable Cause . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

1. Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

1. Appendixes

A: Investigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 B: Cockpit Voice Recorder Transcript . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 C: Correspondence Regarding the First Officer’s Color Vision . . . . . . . . . . . . . . . . . . . . . . . 104

Abbreviations viii Aircraft Accident Report

VOR Very High Frequency Omnidirectional Radio Range

VSI vertical speed indicators

YOW Ottawa MacDonald Cartier International Airport

YWG Winnepeg International Airport

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Figure 1. Descent profile of FedEx flight 1478.

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Figure 2. Descent profile of FedEx flight 1478, with select CVR comments overlaid.

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〔图〕9:34:31 RDO -five clicks9:35:31 HOT-2 gear down, before landing check9:35:42 RDO-1 turing final runway nine9:35:54 HOT-3

Figure 3. A map overlay of FedEx flight 1478's radar track into runway 9 at TLH, with excerpted CVR comments.

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1.2 Injuries to Persons

Table 1. Injury chart.

1.3 Damage to Aircraft

The airplane was destroyed by impact forces and a postcrash fire.

1.4 Other Damage

Trees along the wreckage path were damaged by the impact and postcrash fire. Some farm vehicles and equipment and a fence line were also damaged by the impact.

1.5 Personnel Information

The accident flight crew consisted of three reserve FedEx pilots. The accident flight was the first time all three crewmembers had flown together; however, the captain and flight engineer had flown together once previously.$^{21}$

FedEx operates under 14 CFR Part 121, Subpart S (Flight Time Limitations: Supplemental Operations), which specifies that operators may schedule flight crew members for no more than 8 hours of flight time in a 24-hour period without a rest period within those 8 hours. Pilots must be relieved from duty for at least 24 consecutive hours at least once during any 7 consecutive days. Pilots working in three-person crews can be scheduled for no more than 18 hours of duty in a 24-hour period.$^{22}$ The three accident flight crewmembers had different flight, duty, and sleep schedules before the accident. Table 2 shows their flight schedules for the 24 hours preceding the accident. Table 3

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shows the cumulative flight and duty times for the three crewmembers at the time of the accident, and figure 4 shows the three crewmembers' self-reported estimated sleep schedule during the 72 hours before the accident. All times are reported in central daylight time (the time zone in which the crewmembers were based). Sleep start and end times are estimated from the available verbal reports.

Table 2. Crew members' schedule for the 24 hours preceding the accident.

Table 3. Flight and duty times since the last rest period for the crew of FedEx flight 1478.

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Estimated Sleep Schedule

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Figure 4. The three crewmembers' estimated sleep schedule during the 72 hours before the accident.

1.5.1 The Captain

The captain, age 55, was hired by FedEx on April 10, 1989. He held an airline transport pilot (ATP) certificate (issued August 6, 1999) with a multiengine land rating and a flight engineer certificate for turbojet-powered airplanes. The captain’s ATP certificate indicated type ratings in the 727 (issued August 6, 1999), Cessna CE-500, and Canadair CL-600. According to FedEx training records, the captain’s most recent 727 simulator proficiency check was completed on August 13, 2001; his most recent 727 line check was completed on February 7, 2002; his most recent recurrent simulator training was completed on February 15, 2002; and his most recent recurrent ground training was completed on July 22, 2002. The captain’s most recent Federal Aviation Administration (FAA) first-class airman medical certificate was issued on June 17, 2002, and contained the limitation that he “must wear corrective lenses.”

The captain estimated that he had flown about 13,000 to 14,000 total flight hours. According to FedEx records, at the time of the accident, the captain had about 2,754 flight hours as a 727 flight crewmember, including about 861 hours as 727 pilot-in-command, 515 hours as 727 second-in-command, and 1,378 hours as 727 flight engineer. FedEx records indicated that the captain's proficiency checks were satisfactory and that, in accordance with the company training program, he had received training in visual approaches, non-tower operations, fatigue management, and crew resource management (CRM).$^{23}$ The captain's training records indicated that he had not seen FedEx's black

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〔图〕01137TALLAHASSEE REGIONAL (TLH)AIRPORT DIAGRAMTALLAHASSEE,FLORIDAAL-5048 (FAA)ATIS 119.45 239.25TALLAHASSE TOWER*118.7 2

Figure 5. TLH airport diagram.

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activated about 0534:26, and all lights were on by about 0534:31.$^{42}$ According to CVR and airport lighting activation log evidence, the runway lights were activated on medium intensity.

1.10.2.1 Runway 9 PAPI Lighting System

The PAPI lighting system installed on the left side of the approach end of runway 9 was an ADB, ALNACO, Inc. (a subsidiary of Siemens Airfield Solutions) model L-880, style A, and consisted of four identical light boxes mounted along a line perpendicular to the runway centerline about 1,000 feet from the approach end of the runway. Each of the four boxes contained two 200-watt lamps and optical apparatus to split the lamp beams horizontally into red (lower) and white (upper) beams. The lamps in each of the four light boxes were positioned so that each box projected a signal at a prescribed angle above the horizon, relative to a 3° glidepath.$^{43}$ An on-glidepath signal is represented by the two left-side boxes showing white lights and the two right-side boxes showing red lights. If an airplane is beneath the glidepath, more red lights would be visible to the pilots; if an airplane is above the glidepath, more white lights would be visible. Figure 6 shows PAPI indications from various approach path angles.

〔图〕Too HighSlightly HighOn SlopeSlightly LowToo LowDisplayRunwayEnvironmentIndicationred lightwhite light\n

Figure 6. PAPI indications from various approach path angles.

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broken trees continued to the edge of the wooded area (about 1,130 feet from the initial impact), where the trees on the right and left sides of the swath were broken at 7.9 feet and 31.7 feet, respectively. (Figure 7 shows the swath of damaged trees, looking from east to west, with the first ground scars and airplane wreckage in the foreground.) Pieces of the right wing (including the right wing leading-edge flap, trailing-edge flap, wing tip, strobe light, flap jack screws, and slat tracks) were located in the wooded area.

〔图〕插图

Figure 7. A swath of trees damaged by impact with FedEx flight 1478.

The first evidence of ground impact was located near the edge of the wooded area, about 170 feet from open terrain. The ground scars continued in the open terrain, increasing in width from about 29 feet near the edge of the trees to about 120 feet near the main wreckage. There was evidence of fire along the wreckage path for about 800 feet leading to the main wreckage, which was destroyed by impact and postimpact fire.

The forward fuselage was relatively intact but exhibited impact and fire damage, some of which was severe. The cockpit was severely damaged by fire, with melted and resolidified aluminum draped over the control wheels and pilot seats and the instrument panels destroyed. The lower overhead lighting panel was severely burned and damaged; however, examination revealed that the left and right inboard landing light switches appeared to be in the down, or “on,” position, and the left and right outboard landing light switches appeared to be in the up, or “off,” position. The taxi, navigation, and strobe light switches all appeared to be in the down, or “on,” position.$^{57}$ The five left-side cockpit

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Appendix C

Correspondence Regarding the First Officer's Color Vision

〔图〕插图 DEPARTMENT OF THE AIR FORCE USAF SCHOOL OF AEROSPACE MEDICINE (AFMC) BROOKS CITY-BASE TEXAS

28 Mar 03

MEMORANDUM FOR NATIONAL TRANSPORTATION SAFETY BOARD

ATTN: MITCH GARBER, M.D.

490 L'ENFANT PLAZA EAST, SW

WASHINGTON DC 20594

FROM: USAFSAM/FECO

2507 Kennedy Circle

Brooks City-Base Texas 78235-5116

SUBJECT:

1. The Aeromedical Consultation Service (ACS) of the USAF, School of Aerospace Medicine at Brooks City-Base Texas has completed our aeromedical evaluation on a 44 y/o FedEx 727 pilot with a long standing known color vision (CV) deficiency who was involved in a nonfatal mishap along with two other crewmembers at Tallahassee, Florida on 26 Jul 02. Additional details regarding the final approach to Runway 09 at night and in clear weather are accounted for elsewhere; so only pertinent features related to our evaluation will be stated here.

1. A stated that he was at the controls of the aircraft and was using pilot-controlled PAPI lights during the approach. Although he stated that his memory lapse started about 10 miles prior to impact, he also stated that he was seeing the two white and two red light presentation on the PAPIs, but had provided "half a knob" of additional power when it appeared earlier that the aircraft was approximately one degree below glide slope. He stated that the aircraft was in a stable approach configuration, which was agreed to by all three crewmembers. He stated that he remembers continuing to see the two white and the two red light PAPI configuration. He further stated that he believed that there were indications discovered later that the PAPI lights may not have been operating optimally, but at the time of this evaluation, official verification of their operating condition was not available.

1. Historically, had been a P3 Orion pilot in the Navy and had been qualified as a naval aviator on the basis of passing their primary CV screener, the Famsworth Lantern (FALANT). At that time to our knowledge, the US Navy was not screening for CV deficiencies using Pseudoisochromatic plates (PIPs). According to routine procedures, he was requalified annually throughout his Navy flying career by the FALANT. Later received an FAA waiver without any flight restrictions in 1996 for his CV defect and recalls being tested with a plate test at that time.

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1. At the time of the mishap, he stated that he was using over-the-counter dosage levels of Motrin for a knee injury, but could not recall the actual dose. He admitted to only taking two per day for about a 3-week period. However, as a consequence of serious injuries sustained during the mishap, he was now taking Coumadin for anti-embolic prophylaxis and Hydrocodone for pain, but had previously been on Oxycodone. He reported no other significant ocular history or medical history other than needing spectacles for near and distant vision correction.

1. The NTSB requested that CV testing at the ACS be done under pulse oxymetry to record his oxygen saturation levels during testing.

1. Examination Summary: Complete details of the ophthalmic evaluation will follow. However, a brief summary of the pertinent findings is covered in this letter. He had a small amount of myopia and presbyopia that were both correctable with spectacles to 20/15 O.U. for distance and 20/20 O.U. for near.

1. Color Vision Testing: During CV testing, his oxygen saturation was recorded to be between 98-99% by pulse oymeter. All CV testing was performed monocularly in a darkened room under an approved illuminant and in compliance with individual test instructions and their appropriate time intervals.

a. PIP-I: failed the Dvorine Pseudo-isochromatic plate test, which is a red-green congenital CV PIP screening test. To pass this test and to be regarded as color normal, an individual must have no more than four errors. On the first run, Mr. Frye could only correctly identify 2/14 correct OD and 3/14 correct OS. A repeat test, administered later, produced scores of 7/14 correct OD and 6/14 correct OS. Both of these test scores clearly reflect a failing score as per Dvorine's instructions and based on validation studies performed on that test.

b. PIP-II: scored 9/10 correct in each eye on the Standard Pseudo-isochromatic Plate II (SPPII), which is a PIP test primarily optimized for acquired CV deficiencies, particularly blue-yellow. These are regarded to be passing scores on this test.

c. PIP-III: scored 5/10 correct OD and 9/10 OS on the Standard Pseudoisocratic Plate III (SPPIII) test. This PIP test is a combination of both congenital and acquired red-green and blue-yellow test plates. Based on these scores, he failed this test OD, but passed OS. Furthermore, he failed only red-green CV test plates OD.

d. Farmsworth F2 plate: This single plate test was designed by the Navy to screen for tritan defects. It has some ability to also identify deutans. failed the test with a response consistent with a deutan.

e. D-15: failed the test with a response consistent with a color-weak deutan. He revealed a pattern OD with only one minor transposition and had two minor transpositions OS. There was no major crossing defects suggestive of a deuteranope.

f. The FM-100: failed the FM-100 with scores of 188 OD and 200 OS. Axis analysis revealed a pattern consistent with a deutan.

g. Nagel Anomaloscope: His performance on the Nagel anomaloscope was consistent with a severe deuteranomaly.

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h. Spectrum Colour Vision Meter (Anomaloscope): His blue-yellow metameric match on the Moreland equation was normal, however, his performance on the red-green Rayleigh equation was consistent with a severe deuteranomaly.

i. Farmsworth Lantern (FALANT): He passed the FALANT with 9/9 scores in each eye.

j. The remainder of his eye exam was essentially within normal limits, with no evidence of either lenticular or retinal changes that would suggest an acquired CV defect.

1. A review of his CV testing battery revealed that all test results were consistent with a congenital severe deuteranomaly. This was based on the scores, symmetry, and consistency of his performance on a variety of red-green CV tests and ultimately was confirmed by two different anomaloscopes, performed by two independent examiners. The Motrin dosage he was taking at the time was not believed to be contributing to his CV deficit.

1. did however "pass" the FALANT lantern. When developed, the FALANT was designed to pass approximately 30% of CV defectives (mild deficiencies), which were thought to be compatible with existing aviation tasks at the time. However, multiple studies of the FALANT indicate that it can misclassify even the most severe types of red-green CV deficiencies, and "pass" them. Consequently, it was dropped in 1993 as a secondary USAF qualifying test used in any applicant who failed an initial primary PIP screener. In case, it also appears that the FALANT, did not correctly identify his CV deficiency throughout his entire Navy flying career, nor when administered here at the ACS. However, this notable test "pass" is inconsistent with all other CV testing we performed, but is consistent with a known testing inadequacy in the FALANT. Thus, we concluded that has a severe congenital deuteranomaly and that this defect was not identified properly by the FALANT. This testing inconsistency with the FALANT has been previously documented in the literature.

1. When a variety of CV tests were evaluated by NATO-RTO and published in RTO Technical Report 16, "Operational Colour Vision in the Modern Aviation Environment" in 2001, the following observations were made.

a. "Even though lantern tests have been used for close to one hundred years, their validation and the availability of information on their reliability is almost nonexistent. The evaluation of most lantern tests and the failure rates associated with normals and CV defectives are either conflicting or simply insufficient. Test validation for this class of tests is both complicated and perhaps confusing. Cross validation of one lantern against another is confounded because of the differences in intensity, wavelength, target size and test distances."

b. "Validation of lantern tests by use of an anomaloscope has very rarely been attempted and cross correlation with plate tests has produced ambiguous results." In most cases, therefore, plate tests precede lantern tests with the notable exception of the US Navy where the Farnsworth lantern was used exclusively during this period of time.

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1. Furthermore, we also believe that the type and degree of his congenital red-green defect could result in difficulties interpreting red-green and white signal lights that combine color and brightness, such as PAPIs and VASIs.

a. In 1973 Smith et al. applied a specialized technique to the evaluation of a group of deuteranomalous observers identified by the Nagel anomaloscope. Data relevant to this evaluation indicated that in the range from 510 to 660 nm, which is an area occupied by a considerable portion of the red system, under low light levels the hue was identified as "yellow" whereas when the light was brighter, it was identified as "white". Some observers did see a bit of red in the 660 nm range.

b. The PAPI light red filter produces "aviation red" as specified by MIL-C-25050. It's location in CIE space is at ca. 605 nm, which is in the middle of the red spectrum. Clearly, it is possible in this case, that the red lights of a PAPI could have been identified as "yellow" at lower light levels or "white" when the light was brighter.

1. However, his documented proficiency with over 8,000 flying hours suggests his performance using these devices could employ learned strategies, other than normal color discrimination, to “interpret” PAPIs. Our conclusions assume that the PAPI lights in operation at the time of the mishap were operating normally and were not providing errand information either in wavelength, brightness, or angle. The answer to this technical question, in addition to knowing details regarding the role of the other additional crewmembers, would be required before we could consider any further additional possibilities about the relationship and role of CV and other human or technical factors in this mishap.

P.A. John T. U.O.L.

JOHNT. YATES, Ph.D. Chief, Visual Electrodiagnostic Laboratory

〔图〕插图 DOUGLAS J. IVAN, Col, USAF, MC, CFS Chief, Aerospace Ophthalmology Branch

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〔图〕AFETB0\n Office of Aviation Safety

National Transportation Safety Board

Washington, D.C. 20594

September 17, 2003

Douglas J. Ivan, Col USAF, MC, CFS Chief, Aerospace Ophthalmology Branch Department of the Air Force USAF School of Aerospace Medicine (AFMC) Brooks City-Base Texas

Dear Colonel Ivan:

I am writing in response to the aeromedical evaluation that your branch conducted in support of the NTSB investigation of the FedEx B-727 accident that occurred at Tallahassee, Florida on July 26, 2002. As summarized in your memorandum of March 28, 2003, your laboratory conducted extensive testing on the accident first officer's color vision and concluded that he suffered from a severe congenital deficiency in red/green color perception.

I am writing on behalf of the investigation to ask several further questions to clarify your findings and seek additional documentation regarding your evaluation of the first officer's color vision. The questions are:

1. In your memorandum, you stated that “clearly, it is possible in this case, that the red lights of a PAPI could have been identified as ‘yellow’ at lower light levels or ‘white’ when the light was brighter.” Based on the evaluation:

a) What is the likelihood the first officer would perceive the color red in a PAPI as white, and be unable to distinguish the red and white colors of the PAPI?

b) What is the likelihood the first officer would see the color red as “yellow?” If so, what would be his perception of the color white and would he be able to distinguish the two colors?

c) What is the likelihood that the first officer would perceive the color red in a PAPI as red, pink, or any color that might be readily distinguished from white?

1. You indicated that the first officer might “employ learned strategies, other than normal color discrimination, to ‘interpret’ PAPIs.” What sort of learned strategies were you referring to?

1. Would the first officer have difficulty perceiving the color green in a display such as an airport identifier beacon, and differentiating this color from white and red?

1. How would the first officer’s ability to discriminate between red and white colors on a PAPI be affected by day versus night viewing conditions?

1. How would the first officer’s ability to distinguish red and white lights in a PAPI be affected when these signals were viewed under high relative humidity conditions (but not direct obscuration by fog)?

1. What factors would affect the first officer’s color vision capabilities? Specifically:

a) How would aging affect this type of color vision deficiency? That is, is it likel y that his color perception was better earlier in his career?

b) How would hypoxia affect this type of color vision deficiency? Would his ability to discriminate red and white in a PAPI be affected? Would his ability to discriminate green from white be affected?

c) How would smoking history affect this type of color vision deficiency? The first officer had a ½ pack a day smoking history for his entire adult life. He last smoked about three hours before the accident. Would this smoking history affect his ability to discriminate red and white in a PAPI? Would this smoking history affect his ability to discriminate green from white be affected?

d) What other factors would affect the first officer’s color vision capabilities and how?

1. The first officer received a perfect score on the Farnsworth Lantern test but failed all

other red/green perception tests administered by your laboratory. How was he able to

pass the Farnsworth Lantern test?

1. Can you provide any additional technical references concerning the validity of the

Farnsworth Lantern test for color deficiency testing (including references regarding the

ability of pilots who pass the Farnsworth Lantern to reliably distinguish aviation signals and lights)?

1. Are you aware of any pilots with similar color deficiencies who have had careers in military or civilian aviation? Are you aware of any pilots with similar color deficiencies who have been involved in events/incidents/accidents related to their color vision? What color vision screening methods were used for these pilots?

1. Is it an accurate summary of your test results to state that the first officer was found to have a congenital color perception deficiency sufficiently severe that he could not reliably distinguish the red and white colors of the PAPI based on color information alone?

In your answers to these questions we would particularly appreciate any additional thoughts or

evidence based on your evaluation of the first officer. In addition, any technical references

applicable to assessing color vision discrimination capabilities in individuals with this type and

severity of color deficiency would be appreciated. Thank you for the very thorough and thoughtful support you have provided so far and for your responses to this material.

Sincerely,

Malcolm Brenner, Ph.D.

National Resource Specialist—

Human Performance

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〔图〕“ENEOUNI\n DEPARTMENT OF THE AIR FORCE USAF SCHOOL OF AEROSPACE MEDICINE (AFMC) BROOKS CITY-BASE TEXAS

5 Nov 03

MEMORANDUM FOR NATIONAL TRANSPORTATION SAFETY BOARD

ATTN: MALCOM BRENNER, Ph.D.

WASHINGTON, DC 20594

FROM: USAFSAM/FECO

2507 Kennedy Circle

Brooks City-Base Texas 78235-5116

SUBJECT: FedEx B-727 Accident (July26, 2002), Tallahassee, FL;

NTSB ID#: DCA 02MA054

The USAFSAM evaluation of First Officer ______ in Feb 2003 identified him to have a severe deuteranomalous color vision (CV) deficit that most probably represented a congenital defect based on its long standing history, the characteristics of his defect, and the absence of any other identifiable conditions that would be consistent with an acquired etiology. At the request of NTSB, CV testing was done under monitoring by pulse oymetry, which revealed normal hemoglobin oxygenation levels during testing. If First Officer ______ was alone in his visual interrogation and interpretation of the PAPI system, then it was the only available visible external cue he had to land the aircraft that night. With that in mind, we will now address the specific questions you have posed, in sequence:

1. His red-green CV discrimination was significantly impaired as identified on multiple red-green CV screening tests. Ultimately, he was characterized to be severely deuteranomalous, and nearly dichromatic, on anomaloscopic testing. Thus, compared to normal, his perceptible spectral bandwidth of colors would be quite narrow, likely approaching monochromatism above 540-545nm. This would essentially relegate him very nearly to a gray-blue-yellow world only. In that abnormally color shifted world, such an individual would have extreme difficulty, determining differences between greens and reds and many other colors to include whites based on wavelength or hue. The physiological nature of such a CV deficit is caused by an abnormal shift in the wavelength sensitivity of the green cone system from its normal position in the visible spectrum, towards, and nearly overlapping the wavelength sensitivity curve of the red cone system located at the longer wavelength section of the visible spectrum. A total shift would completely overlap the red cone system rendering such an individual dichromatic and a severe enough shift would also effectively render such an individual to be nearly dichromatic and still make red and green lights and most colors virtually

indistinguishable. Thus, the ability to appreciate differences in colors as normally

generated by appropriate independent and simultaneous stimulation of normally

separated red and green cone sensitivity curves would be severely compromised and

abnormal. That independent stimulation of separate cone sensitivity curves located in

different parts of the visible spectrum is required by the brain to determine appropriate

matches that eventually define normal color perception. When the cone sensitivity

curves abnormally overlap, wholly or in part, this ability becomes aberrant. The greater

the overlap, the greater the problem. For example, conceptually, simultaneous

stimulation of a single sensitivity curve by a purish source with a narrow wavelength

range, such as a laser, would normally trigger only 1 cone system. However, with

overlapping curves, that same light source would now be interpreted by the brain to be

stimulating two different cone systems and be centrally processed to represent a color

other than a purish red or green, because of the two cone systems now being stimulated

(abnormally) at the same time and processed accordingly by the brain. Therefore, a

light source or object that would appear to be red or green to a color normal would now

appear to be something other than red or green to someone with this type of severe cone

sensitivity shift, and more likely be interpreted as yellow. Therefore, because of the

severity of his CV deficit, we believe that he would definitely have had problems

discriminating the PAPIs normally, and as they were designed, because the red lights

would appear not to be red at all, but either yellow, or some other wavelength, that

would make them more indistinguishable from white, especially if the light sources

were further intensified. Therefore, given the congenital near overlap of his red-green

cone sensitivity curves, it would be extremely unlikely that he would be capable of

seeing even the color pink on the PAPI, but more likely, a combination of whites and

yellows and perhaps, not even that difference.

1. Congenital color defectives develop some ability to “differentiate” between normal

colors based on clues other than hue or wavelength, such as by differences in shade or

brightness. This is a learned process and is not reliable. Over time, they adjust to their

“abnormal” color world and learn to assign typical color names to that perceived

difference based on learned experiences. Such adjustments are not foolproof and are

vulnerable to failure, especially when exposed to unpredictable and new color

challenges without redundancy. Therefore, it might be possible for someone with this

type of CV deficiency to use brightness differences between the white and red PAPI

lights to help differentiate between them over an entire flying career. However, on the

other hand, someone like this may also not have been able to use PAPIs effectively at

all over their entire career, especially exclusively. If the "difference" between the white

and red lights were somehow perceptible enough, someone could eventually learn how

to use this information to analyze such challenges, but more likely, this would have

caused such an individual to shy away from sole reliance on PAPIs. Such a strategy

would be more effective in a CV defective, if the targets being interrogated, were

limited, repeatable, and reproducible, such as in the Farnsworth Lantern (FALANT) or

in the PAPI system, where learned strategies could be effectively tested by trial and

error and employed. However, new and unexpected color tasks or lighting situations

would be much more challenging or even impossible, to an individual with this level of

CV defect, especially the first time encountered, than situations that can be uniformally

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reproduced, retested, and represented over and over. That said, it is possible for an individual with this level of CV defect to quickly learn how to pass some color challenges based on limited selection options and other technical limitations, such as those known to be associated with the FALANT. Once someone learned how to assign a new color name for each particular brightness, or to any differences they might perceive, they could employ this strategy in order to "pass" the FALANT again and again. Remember, CV defectives have been trying to naturally adopt alternate strategies all their lives in order to adapt, function, and survive in their abnormal color world. However, we would expect that the first time someone with a severe red-green CV defect were administered the FALANT, that they would have had trouble truly passing it and would have needed time or additional testing to develop a strategy to "pass". To "pass" the FALANT, correct responses to the presentations are required. The testee is trying to "pass" the test, therefore, their goal is to give "correct" responses. Being unaware of normal colors and of their inability to truly identify hue based differences during the test, they would nonetheless try to give "correct" responses from their perspective based on how they have learned to differentiate between the choices. Therefore, they are trying to give the right answers without really being able to normally appreciate the differences as was intended by the test. They in fact know no other way and have had a lifetime trying to respond to color differentiation tasks that are obvious to color normals. Technicians are listening for responses and would not easily recognize "problems" beyond "right" or "wrong" responses. In fact, some may unintentionally "help" in the process. With only a known and limited number of colors and choices in FALANT combinations, and some adopted strategies that "differentiates" between the three, it can be conceived that such an individual could have consistently "passed" the FALANT using an alternate strategy, rather than actually being able to truly differentiate between the red, green, and white wavelengths as perceived by a normal trichromat. Paulsen et al.(1966), and others since have reported this. It should also be kept in mind that by design, the FALANT test was never designed to identify only color normals, but to allow some CV defectives to be passed and therefore be indistinguishable from true normals who also pass. However, it should not in theory pass more severe CV deficits, but unfortunately does so.

1. An individual with type of CV defect is nearly a dichromat. As stated earlier, this means that the wavelength sensitivity curves of the red and green systems would be nearly overlapped, thus mimi cking a single responding "red-green" cone system and true dichromatism. Consequently, such a red-green dichromat would be relegated to a world of grays, blues and yellows. Someone like him would be expected to have problems truly differentiating between red and green wavelengths, and in fact possibly all wavelengths greater than 545nm. Common errors include confusing whites with reds and greens, e.g., calling white lights red and vice versa.

1. His ability to see the PAPIs differently during the day or at night might vary depending

on the intensity level selected for the PAPIs. Since the perception of the PAPI lights

would be a photopic event in either case at these light levels, the same confusion would

likely exist day or night, with one exception. Given the scenario he was under, at an

unfamiliar airfield, at night, in a black hole with no other visual cues available for him

to interrogate other than the PAPIs, published literature by Smith, et al.(1973) in

similar CV defectives, including severe deuteranomalous individuals, clearly indicated

that hues in the range between 500-600 nm were identified as yellow at reduced

illumination levels, but when these wavelengths were intensified, the brighter colored lights were now interpreted as “white”. In addition, low voltage levels of white PAPI lights are known to shift the white lights more towards yellow (Cole and Maddocks). This output driven wavelength shift would make it more difficult, or even impossible, for such CV defectives to distinguish differences between white, red, and yellow.

1. We do not have enough information available to us to answer this question. There are studies in the literature on atmospheric haze effects, but none that we could find on

humidity.

6a. One of the characteristics of congenital CV defects is that they do not change over time unless an additional acquired etiology occurs and thereby overlays an additional

component on the already underlying congenital defect. That would only make

matters worse. The only age related issue that could possibly impact this case would be from any induced blue light filtration caused by the natural yellowing of the lens

that occurs in everyone over time. This is a well-known UV-induced phenomenon that can induce an acquired blue-yellow deficiency by blocking shorter wavelengths, e.g., purples, and blues. We did not demonstrate any obvious cataract in his case, however, even a normal lens is known to have increasing levels of blue and UV filtration as a

function of increasing age. Such an acquired blue-yellow CV disturbance would likely not aggravate existing red-green problems, however, could tend to aggravate the ability to distinguish residual differences between yellow and white, as this would be

tantamount to wearing yellow lenses. However, he did not demonstrate an objective

blue-yellow component at this point in time.

b. Hypoxia can definitely degrade visual function including color vision. This has been

well established in the literature for years. The WW2 literature available from Schmidt identified increased pathological color thresholds (red and green both decreased in

sensitivity, but in different subjects) with mild hypoxia above 9800 ft. and observed

this to be even greater if there was an already existing color deficiency.

The following paragraph with respect to hypoxia and color vision was extracted from

the Heino Widdel and David L. Post edited book entitled "Color in Electronic

Displays", Defense Research Series, Vol 3, 1992:

"Several studies have reported that hypoxia results in losses in color sensitivity,

although there is disagreement on the specific effects (see Dyer, 1988). When color

vision has been tested foveally, the hypoxia generally produced a greater perceptual

deficit for blue or green (Frantsen & Iusfin, 1958; Modugno, 1982; Schmidt & Bingel, 1953; Smith, Ernest & Pokorny, 1976; Weitzman, Kinney, & Luria, 1969); when it was tested peripherally, it generally produced a greater deficit for yellow or red (Blum &

Fisher, 1942; Ernest & Krill, 1971; Kobrick, 1970; Vollmer, King, Fisher, & Birren,

1946). On the other hand, in testing the effects of hypoxia on the limits of the visual

field, Kobrick, Zwick, Witt, and Devine (1984) found that the limits of green sensitivity decreased but not hose of red. Boles-Carenini and Cima (1952) noted that hypoxia

worsened already-existing anomalies of the Nagel anomaloscope quotient."

Therefore, hypoxia could be expected to induce or further degrade any residual hue

discrimination by raising the color sensitivity thresholds overall and reduce any

residual wavelength discrimination across the visible spectrum. All colors become

further degraded under lower levels of illumination, especially with hypoxia. These

hypoxic effects have generally been studied using the FM100, but we could not find

any other studies addressing hypoxia as a function of any other specific CV tests

beyond those cited using the FM100 and Nagel anomaloscope.

c. Research has indicated that smoking also affects photopic vision, one aspect of which would be color perception. This can occur from related hypoxic and metabolic effects or from tobacco amblyopia, a type of chronic toxic optic neuropathy, usually seen in

heavy smokers. Graefes (Arch Clin Exp Ophthal, 1999, May, pp 377-80) identified

color vision changes in individuals who consumed more than 20 cigarettes per day.

d. Other potential factors that could affect anyone’s color vision would include the nature, transmission characteristics, and color of any intervening optical interfaces,

medications, drugs, and/or diseases that might also be present. These all would reduce brightness, change the spectral characteristics entering the eye or receptor sensitivities, and further degrade cone function. Our evaluation however did not reveal any known indication of any medications or diseases that would further impact his color

perception in any way. A typical Boeing 727 windscreen would not normally be

associated with any selective waveband filtration that would have further degraded the visual scene external to the cockpit in any significant way. However, specific FedEx

modifications would need to be ruled out.

1. We believe that the First Officer was able to “pass” the Farnsworth Lantern using

naturally learned strategies as previously discussed. His learned experience may have involved some early, unrecorded test failures and perhaps, some technician “assistance” along the way. This could have been as benign as allowing someone like him some

additional opportunities to change a response or even retake the test. On the other

hand, the FALANT is known to “pass” severe CV defectives, however that occurs.

Regardless, the FALANT was the only color vision test that he could “pass” at

USAFSAM. All other test scores were consistent with a severe red-green deficit. The

D15 was borderline. While this may appear disconcerting, it is not surprising and is

consistent with known problems with the FALANT.

1. A database literature search would provide you with a complete bibliography with

respect to the FALANT. In addition to references you already have, I would draw your

attention to germane articles recently published in Aviation, Space, and Environmental

Medicine in the last few years as a good start, as well as a few others linked below:

(a) Birch and Dain, ASEM, Vol 70, No. 1, 1999.

(b) Dain and Houson, ASEM, Vol 59, No. 4, 1988.

(c) Laxar, Military Medicine, Sept, 1967, pp 726-731.

(d) Cole BL and Maddocks, JD, “Colour Vision and PAPI”, Colour

Deficiencies XII, 1995, pp 501-510.

(e) Cole and Vingrys, Documenta Ophthalmologica, 55, 1983, pp 157-175.

The simulated PAPI Study by Cole and Maddocks (d) in particular identified

unexpected problems with all deutans, both deuteranopes and deuteranomalous, that led

them to conclude that proper recognition of PAPI systems by color defectives is

problematic and a risk in aviation.

Because of testing inaccuracies and other flaws of FALANT testing applicable to

modern aviation, it was dropped as an official USAF aircrew qualifying test in 1993. It

simply was not reliable and misidentified significant CV defectives. (See below).

1. Prior to 1993, and throughout the entire history of the use of the FALANT in the Navy

and USAF, passing the test meant that you met applicable CV standards at the time and

did not require any further CV testing. Therefore, since many color defectives can

“pass” the FALANT, the true CV status of an individual who passes it, cannot be

determined on the basis of passing that test alone. Procedurally, for decades, the USAF

used a red-green PIP-I screener first, and then, only if you failed that test, were you

administered the FALANT. If you failed the FALANT, you were disqualified. If you

passed the FALANT, you were qualified and no further definitive quantitative analysis

was required. PIP testing became the only standard used by the USAF between 1993

and 1995, when a transition to the present methodology was adopted.

Currently the USAF uses a four-test battery of PIP plate tests to evaluate pilot

applicants during Medical Flight Screening (MFS) for both congenital and acquired

red-green and blue-yellow CV deficiencies. To qualify for MFS, an applicant must

first pass an Initial Flying Class I exam including the traditional single red/green

screening PIP test exam done in the field. The additional four test CV battery is then

administered to all pilot candidates during MFS at USAFSAM. It comprises the PIP I,

PIP II, PIP III, and the F2 plate tests. Failure of any one of those four PIP plate tests

results in additional color vision (CV) testing to determine the exact nature and degree

of any existing CV defect and a complete ophthalmological evaluation to rule out

acquired pathology. The final CV determinant test is the gold standard anomaloscope. However, many additional CV tests (FM100, FALANT, APT-5, D15, etc.) are also

performed to monitor their effectiveness and correlation with the screening test battery and the anomaloscope, however, their results do not impact on the final waiver

recommendation, only the anomaloscope results count at this point. This CV screening methodology is consistent with the recommendation of NATO’s Working Group 24

that was published in RTO-TR-016 in 2001. Because of many problems related to

lantern tests, WG-24 did not recommend using any lanterns for CV screening and

assessment for modern aircrew. Previous published studies of the FALANT have

revealed that it “passes” between 25-40% of all color defectives while in theory it was designed to only pass mild deficiencies. That proven unre liability was the fundamental reason why the USAF dropped it as a CV qualifying test in 1993. Repeated analysis of the FALANT results in CV defectives at USAFSAM indicate that the FALANT does

not distinguish or predict the magnitude of the CV deficiency and passes mild,

moderate and severe anomalous trichromats. It is usually failed by dichromats. More

specifically, in the most recently analyzed data submitted for presentation for AsMA

2004, the FALANT passed 60% of subjects identified to have severe deuteranomaly on the anomaloscope.

Given intended and unintended flaws associated with the FALANT, it therefore

remains unknown how severe a color defective might be if they “passed” the FALANT. There is some data however on this in the literature to incl ude the additional experience here at USAFSAM with large numbers of applicants. Therefore, it is possible that

aircrew with similar defects managed to escape accurate identification of their true CV performance because of "passing" the FALANT. It has been subsequently shown that some can have significant CV deficits.

An apparent paradox exists in that, because of the absence of any disastrous accidents, aviators may appear, and is often argued, to have performed “successfully” throughout their career. This perception is likely due to a myriad of circumstances, but would

represent a spectrum to include not being appropriately challenged, or even being just

plain lucky! Being “successful” therefore can be misleading in some cases, as we

believe it appears in this case. That “success” may vanish if their CV deficiency gets

challenged in a way that their handicap fails them. We are aware of another Navy

aircraft mishap that can be attributed to a very similar scenario involving a CV

defective, as severe as this case, who also apparently “passed’ the FALANT many

times over his career. Following a series of color vision misperceptions during a flight that resulted in the loss of the aircraft, that mishap pilot was later identified to also be

severely red-green CV defective and quite similar to the type of the CV defect in this

case. During the post accident investigation, he admitted that he had gotten “help” and used alternate strategies to “game” the FALANT in order to “pass” it. Technicians

“helped” in assorted ways. Anomaloscope testing in his case also revealed a severe

red-green deuteranomalous CV deficiency.

1. In summary, we believe that this case appears to be consistent with a true failure in CV

testing methodology involving the FALANT’s inability to properly identify a severe

red-green CV defective who found himself in a scenario when the PAPI system was

the, main and possibly only, clue available to help him successfully land the aircraft at

an unfamiliar airfield, despite his past history of apparent “success”. The failure to

properly identify his CV deficit is consistent with one of the potential problems

associated with reliance on the FALANT, and is further consistent with other research

in CV defectives using colored lights similar to the PAPIs. In this setting, we believe

he would not have been able to properly interpret the PAPI system as designed because

of his severe congenital red-green color vision disturbance.

JOHN T. YATES, Ph.D.

Chief, Visual Electrodiagnostic Laboratory

DOUGLAS J. IVAN, Col, USAF, MC, CFS Chief, Aerospace Ophthalmology Branch