Aircraft Accident Report, Southern Airways, Inc., DC-9, N97S, Tri-State Airport, Huntington, West Virginia, November 14, 1970/Investigation

by National Transportation Safety Board

 

1. INVESTIGATION

1.1 History of the Flight

Southern Airways Charter Flight 932 (SOU 932)^[1] was scheduled as a ferry flight from Atlanta, Georgia, to Kinston, North Carolina, to return members of the Marshall University football team, the coaching staff, and other passengers to Huntington, West Virginia, from Kinston. The flight was then scheduled to continue to Hopkinsville, Kentucky, and Alexandria and Baton Rouge, Louisiana. The crew consisted of a captain, a first officer, and two stewardesses. In addition, an operations employee was assigned as a charter coordinator.

The flightcrew was given a standard briefing by company dispatch and a charter kit of appropriate documents including: (1) Jeppesen Manuals for high and low altitude airways, and approach charts for all major and military airports in the U.S.; (2) the current Airman's Information Manual, Part I, II, and III; (3) a complete set of Sectional Aeronautical Charts; and (4) all the necessary flight forms of cargo loading, weight and balance, flight planning, daily inspections and maintenance, and credit cards. In addition, a copy of the Southern DC-9 off-line airport restrictions was carried by the charter coordinator, and another copy was kept on each aircraft. The stewardesses and charter coordinator boarded the aircraft with the flightcrew at Atlanta and the aircraft was ferried to Kinston.

The flight departed Atlanta at 1548^[2] and arrived at Kinston at 1642. The aircraft was refueled, but no maintenance was requested or performed. Seventy passengers boarded the aircraft and the flight taxied from the famp at 1828 with a total of 75 persons aboard.

The captain filed an Instrument Flight Rules (IFR) flight plan to Huntington, via direct Raleigh—Durham, North Carolina, direct Pulaski, Virginia, direct Huntington, at Flight Level 260 (FL 260). The true airspeed was 473 knots and the estimated time en route was 52 minutes. The flight departed Kinston at 1838 and proceeded in accordance with the flight plan. Subsequent air traffic control transfers were accomplished and, at 1923, SOU 932 established contact with Huntington Approach Control by advising, "... we're descending to five thousand."^[3] The controller cleared them for a localizer approach to Runway 11 and added, "... the surface winds are favoring runway twenty-nine, three five zero degrees at six, altimeter two niner six seven..." The crew acknowledged this information and then the controller advised, "... the Huntington weather three hundred scattered, measured ceiling five hundred, variable broken, one thousand one hundred overcast, visibility five, light rain, fog, smoke, ceiling ragged variable four to six hundred."

At approximately 1933, the captain said that he would fly at 130 knots, and the first officer responded that he was checking the time, and the approach should take 2 minutes. At 1934, the crew reported passing the outer marker inbound, and they were cleared to land. The wind was then reported as 340°, 7 knots. Following a discussion of the approach lighting during which the crew requested "step three," the tower controller stated, "Roger, that's where they are, with the rabbit (sequence flasher). Advise when you want them cut." The crew's response, "Very good," was the last transcription received. At approximately 1936, tower personnel observed a red glow west of the airport. When no response to subsequent radio calls was received, the tower controller initiated the emergency.

Witnesses in the vicinity of the Runway 11 localizer course generally agreed that the aircraft was low, but otherwise appeared normal. The weather was described as vary between mist and light rain with low clouds. Some witnesses also indicated that visibility was restricted due to fog. However, one witness who was approximately two-thirds of a mile west of the initial impact site observed the aircraft pass approximately 300 feet above him and disappear from view beyond the hill. He saw the hill outlined in "good detail" by a glow from beyond the hill, and heard an increase in jet engine noise prior to the crash. Another witness, who was approximately 700 feet east of the initial impact, stated that the aircraft rolled to the right, almost inverted, and crashed into a steep, nosedown angle.

The tower controller stated that he maintained a continuous watch for SOU 932 once they reported passing the outer marker. Although he did not see the aircraft, he did observe the fire and explosion from the crash. He did not recall any differences between the reported and actual weather prior to the accident.

The last flight to operate into Huntington prior to SOU 932 landed on Runway 11 at 1848 and departed at 1907. The captain of that flight stated that the weather was essentially as reported to him, 300 feet scattered, 500 feet variable broken. They broke out of the clouds at minimums, west of the refinery (located approximately 2 miles west of the airport). The forward visibility was good, and the runway was in sight from this point until they landed, although they did encounter some widely scattered scud clouds.

The accident occurred during the hours of darkness at 38° 22' 27" N. latitude and 82° 34' 42" W. longitude.

1.2 Injuries to Persons

Injuries	Crew	Passengers	Others
Fatal	4	71	0
Nonfatal	0	0	0
None	0	0	0

1.3 Damage to Aircraft

The aircraft was destroyed by impact and ground fire.

1.4 Other Damage

The aircraft destroyed many trees on a hill approximately 1,300 feet west of the main wreckage site.

1.5 Crew Information

The crew was qualified for the flight. (See Appendix B for details.)

1.6 Aircraft Information

The aircraft was certificated and maintained in accordance with existing regulations. It was fueled with Jet A-1 kerosene. (See Appendix C for details.)

1.7 Meteorological Information

At the time of the accident, a low-pressure area was centered near southwestern West Virginia. A frontal system extended southward from that area and the accident site was included in an extensive zone of low cloudiness and precipitation associated with these synoptic features.

The aviation area forecast for West Virginia, issued by the National Weather Service (NWS) office at Suitland, Maryland, valid for a 12 hour period, beginning at 1400, was, in part, as follows

Low pressure developing over the southeastern states and centered over northeastern Alabama, expected to move northeastward at 15 to 20 knots will lie over western North Carolina southwestern Virginia by 0200.

Flight precaution recommended throughout forecast area because of lowering ceilings and visibilities and also because of occasional turbulence and possible icing.

Over West Virginia... generally ceiling 1,000 to 2,000 feet overcast, 3 to 6 miles, haze, occasional ceiling 300 to 500 feet overcast, 1 to 2 miles, fog, scattered right. Conditions lowering more extensively after 1700, becoming more frequently ceiling 500 to 1,00 feet overcast, 1-1/2 to 3 miles, light rain, fog, and occasional ceiling 300 to 500 feet overcast, 3/4 to 1-1/2 miles, light rain, fog, with light rain to occasional moderate rain.

Freezing level 6,000 to 8,000 feet over mountains... occasional moderate icing in clouds likely above freezing level...

The terminal forecast for Huntington, issued at 1145, and valid for a 12- hour period beginning at 1200 was in part as follows:

1200-2100, ceiling 500 feet overcast, w miles, light rain, fog, smoke, wind 030°, 12 knots, variable to ceiling 300 feet overcast, 1 mile, light rain, fog.

The next routine terminal forecast was issued at 1745, valid for a 12-hour period beginning at 1800 and was in part as follows:

1800-2300, 300 feet scattered, ceiling 500 feet broken, 1,00 feet overcast, 1-1/2 miles, light rain, fog, scattered clouds variable to broken.

The official surface weather observations for Huntington bracketing the time of the accident were as follows:

1855, 300 feet scattered, measured 500 feet variable broken, 1,100 feet overcast, 5 miles, light rain, fog, smoke, temperature 49°, dewpoint 47°, wind 360°, 4 knot, 29-67, ceiling ragged and variable 400 to 600 feet.

1945, 300 feet scattered, estimated 500 feet broken, 1,000 feet overcast, 5 miles, light rain, fog, smoke, temperature 49°, dewpoint 47°, wind 210°, 4 knots, 29.67, ceiling ragged, aircraft accident.

1956, record special, partial obscuration, estimated 500 overcast, 3/4-mile very light rain, fog, smoke, temperature 49°, dewpoint 47°, wind 290°, 5 knots, 29.67, fog obscuring 5/10 of the sky, ceiling ragged, intermittent very light rain.

The National Weather Service specialist who made the observations testified that "... I thought the visibility was remarkably good when I took my local (the 1945 observation), but about 10 or 15 minutes after that the fog formed very rapidly, and that's when the visibility came down... it was right over the field. It just seemed like it formed very rapidly and it just actually sank right over the whole field."

The Huntington 1900 radiosonde ascent showed saturated or virtually saturated conditions with stable air from about 2,000 to 5,000 feet and otherwise a moist adiabatic lapse rate. The freezing level was at 7,500 feet. The upper wind observation associated with his ascent was in part as follows.

Height (feet m.s.l.)	Direction (°true)	Velocity knots
Surface	360	7
2,000	075	12
3,000	130	18

A study of pressure patterns in the West Virginia area, at the time of the accident, was conducted for the Safety Board by the National Weather Service following the initial public hearing. The study showed that the dominant low-pressure area was elongated toward the northeast with surface pressures dropping at an average rate of 0.013 inch of mercury/hour. This would correspond to an indicated altitude increase of 13 feet/hour. The low-pressure area moved steady northeastward with little change in intensity. Although there was an extensive area of light rain, no showery precipitation (possibly indicative of more rapid fire variation) was reported within 250 miles of Huntington.

1.8 Aids to Navigation

The Tri-State Airport was equipped with an ILS localizer, but no glide slope. The localizer provided a nonprecision approach to Runway 11. The crew's Jeppesen Approach Chart depicting this procedure was dated December 27, 1968; however, the current approach chart at the time of the accident was dated November 6, 1970. (See Attachment 2.) The revised approach chart was incorporated in Southern's charter kits on November 13, 1970, by the chief pilot. Two kits were not available on that date because they were in use at that time, including the charter kit on N97S which had departed at approximately 0830 on this day the revisions were inserted. The basic differences in the two approach charts were: (1) an increase in the Minimum Sector Altitude^[4] from 2,500 feet to 2,600 feet m.s.l., for the sector west of the airport (180° clockwise through 360° inclusive); and (2) the addition of holding instructions to the missed-approach procedure text.

The Localizer-Runway 11 approach required a procedure turn southof the 114° localizer course within 10 miles of the outer marker, at 2,600 feet m.s.l. The outer marker minimum crossing altitude was 2,200 feet m.s.l., and further descent was then authorized to the Minimum Descent Altitude (MDA)^[5] of 1,240 feet m.s.l. The outer marker and middle marker were located 4.6 and 0.6 miles, respectively, from the runway threshold. The Localizer was offset approximately 0.07° to the south of the runway centerline. The offset was accomplished to place the antenna on stable ground where the electronic signal would remain within tolerances. A flight check of the facilities was accomplished by the Federal Aviation Administration (FAA) on November 15, 1970, and all were found satisfactory.

An instrument landing system was scheduled for installation and commissioning at the Tri-State Airport in June 1958. The localizer, middle marker, and outer marker installations were completed at that time, but there was insufficient terrain to provide adequate reflecting surface for the glide-slope antenna, within the existing criteria. Three applications for runway extension, which would also provide suitable terrain for the glide-slope antenna, were submitted to the FAA in Fiscal Years 1967, 1970 and 1971. The 1967 and 1970 requests were not approved because the necessary "matching funds" from the sponsoring agency were not available, and consequently the Federal funds were not committed. The 1971 request was still under consideration at the time of the accident.

Subsequent to the accident, concurrent negotiations involving the FAA, West Virginia State Aeronautics Commission, Wilcox Electric Company, Inc., and the Tri-State Airport Authority, resulted in the installation of a nonstandard glide slope for Runway 11, paid for by Federal funds only. Prior to installation, the FAA estimated that there was a 50 percent probability of success with the glide slope. A Wilcox Mark I, Series 8020 transmitter was placed 1,211 feet south of the runway centerline and 960 feet west of the Runway 29 threshold. The elevation of the site was 805.2 feet m.s.l. and the antenna was rotated 13.5° to align with the middle marker. This offset was required to place the site on suitable terrain, and resulted in an unusable signal below 1,075 feet m.s.l. Consequently, there was no reduction in the minimum altitude authorized for the instrument approach. However, the signal generating capability of the facility to date has been as reliable as the standard systems.

1.9 Communications

There were no known difficulties with radio communications.

1.10 Aerodrome and Ground Facilities

The Tri-State Airport was located on a hilltop approximately 2.5 miles southwest of Huntington, West Virginia, at an elevation of 828 feet m. s. l. The only runway was Runway 11-29. It was 5, 281 feet long and 150 feet wide, and was of concrete construction. Runway 11 was equipped with high-intensity runway lights, approach lights, and sequence flashers. All lighting was operating satisfactorily. There was no visual approach slope indicator (VASI) system installed.

There was very little level land extending beyond either end of the runway; however, there were other hills of similar size and elevation surrounding the airport. The highest obstacle in the area underlying the localizer was a tree 6,700 feet east of the outer marker, at an elevation of 990 feet m.s.l. By contrast, the Ohio River and Big Sandy River passed within a few miles of the airport at elevations of approximately 500 feet m.s.l. in the north, west, and south quadrants. An area of bright lights surrounding a refinery was located on the west bank of the Big Sandy River just south of the localizer course, about 2 miles west of the runway threshold.

1.11 Flight Recorders The aircraft was equipped with a Sundstrand flight data recorder, Model F-542, S/N 1047. The recorder unit had been exposed to extreme heat in the fire after the impact, but the recording medium magazine was easily removed and the recorded foil surface was virtually undamaged. A readout of the last 10 minutes of normally recorded traces were prepared. The altitude trace was adjusted for an altimeter setting of 29.67 to indicate m.s.l. altitudes, but no other corrections were made to the data. Additional checks of the altitude trace were made as follows:

Location	Altimeter Setting	Recorded Difference	Tolerance
Atlanta Airport	29.71	- 18 feet	± 100 feet
Cruise FL 290	29.92	+ 200	± 450
Stallings Field (Kingston	29.90	+ 88	± 100
Cruise FL 260	29.9	+ 235	± 400

The last 0.036-inch of foil travel contained sudden deviations in all recorded traces. The aberrant area, equivalent to 21.6 seconds of elapsed time during normal operation, included a 0.009-inch segment without the recording of any parameter trace. With the assistance of the manufacturer, various tests were conducted to duplicate the indications on the flight data recorder foil. Mechanical and electrical checks, g-loading on all three axes with indiscriminate interruptions of electrical power, and attempts mechanically to impede or accelerate foil travel all failed to provide a satisfactory explanation for the aberrations. It was determined that the 0.009-inch skip was caused by a shock of unknown magnitude or origin. Also, though some scribe marks during the 0.035-inch travel were normal in appearance, there was no correlation between the recorded parameters, except that the downward excursions appeared to have been caused by a heavy shock in excess of 30g's

The flight data recorder static pressure source is the aircraft alternative static system. This system is completely separate from the captain's and first officer's normal static pressure systems, except that it is available as a backup source for their instruments, if selected by them. The alternate static ports are located on either side of the aircraft centerline approximately 10 feet forward, and slightly below, the normal static port panels.

The aircraft was also equipped with a Collins cockpit voice recorder (CVR), Model 642-C-1, S/N 508. The unit has sustained considerable impact damage to the electronics package, but there was no damage within the stainless steel case of the tape magazine. There was considerabl "wow and flutter" on the tape, indicating a mechanical distress condition within the recorder. There was also marked interference from background noise and the cockpit speakers. A partial transcript of the readout is attached as Appendix D.

1.12 Wreckage

The aircraft initially struck trees on a hill 5,542 feet west of the runway threshold, and cut a swath 95 feet wide and 279 feet long through the trees on a bearing of 110°, 122 feet right of the Runway 11 centerline extended. Several sections of wing leading edge, one trailing edge flap moveable vane, and a flap track, all from the right wing, and three large sections of radome were located near the swath cut.

The main wreckage site was located 4,219 feet from the threshold of Runway 11, and approximately 225 feet south of the middle marker. The aircraft cut a swath 39° below the horizontal through the trees at the wreckage site and came to rest in an inverted attitude.

The ground elevation at the initial tree impact was 860 feet m.s.l., and the elevation at the break of the tree at this location was 916 feet 2 inches m.s.l. The highest ground elevation adjacent to the swath cut was 894.5 feet m.s.l. Tree heights at this point measured 50 feet, which corresponded to a treetop elevation of 944.5 feet m.s.l. The ground elevation near the crest of the hill in the center of the swath cut was 880 feet m.s.l. The break in a poplar tree at this point was 42 feet above the ground (922 feet m.s.l.) However, the U. S. Department of Agriculture Forest Service estimated that the tree was 71 feet (±1 foot) tall before breakage, based on a study of other trees in the area. The MDA was approximately 290 feet above the estimated maximum elevation of the tree top. The swath cut between the initial tree impact and the break in the poplar tree was +2°, measured from the horizontal. The distance between these two trees was approximately 152 feet.

Most of the fuselage was melted or reduced to a powder-like substance; however, several large pieces were scattered throughout the burned area. Examination of the various components indicated that the landing gear and flaps were fully extended at impact. The horizontal stabilizer setting was 5.75 units noseup, which was in the normal range for the weight, and speed, in the approach configuration.

1.13 Fire

A severe ground fire at the main wreckage site followed impact. Firefighting activity at the crash site was limited to containing brush fires in the area. There was no evidence of in-flight fire.

1.14 Survival Aspects

This was a nonsurvivable accident.

1.15 Tests and Research

In reviewing the circumstances of this accident, the safety board again took notice of tests conducted by the Douglas Aircraft Company (DACO) in May 1967. The tests were designed to study the effect of possible water ingestion at the static ports of the aircraft. Several DACO field service reports had indicated that during final descent on ILS approaches, with full flaps and landing gear extended, the altimeter was alternately "pausing" and then "jumping." At each momentary pause and subsequent jump, the instantaneous vertical speed indicator tended toward zero. Most of the "jumps" were between 40 and 60 feet, but several were 80 to 100 feet in magnitude.

The initial tests were conducted in an altitude chamber. It was found that each port of the static plate entrained water by capillary action, and pressure differentials equivalent to about 35 feet in altitude, at sea level, were required to expel the water. A series of runs verified that any increase in the diameter of the orifice decreased the magnitude of the "jumps." Variations in the rate of descent affected the rate of "jumps," but not the magnitude.

Flow visualization tests were then conducted in the wind tunnel with 1/50-scale DC-9-10 and DC-8-55 models to identify any mechanism that might tend to concentrate water in the vicinity of the static ports. The testing covered both no-flap and 50°-flap configurations at angles of attack ranging from -8° to +8°. The observed flow was orderly, and the only deviation was around a high velocity region on the nose of the DC-9. This was later found to be due to model asymmetry.

Actual flight tests were conducted in light-to-heavy rain with a DC-9-30 in the following flight conditions: descent in the landing configuration for both the DC-9-10^[6] and DC-9-30, and descent in the clean configuration that was representative of both aircraft. Nine simulated ILS approaches were flown in the DC-9-30 landing configuration.^[7] Both the normal and alternative static systems were monitored throughout, and no instances of sticky altimeter operation were observed. Additionally, five typical descents were made in the clean configuration, at 2,500 to 3,000 feet/minute, through light to sporadically heavy rain. No evidence of sticky altimeter operation was detected on any system.

At the request of the Safety Board and the FAA, the National Aeronautics and Space Administration has taken a long term Static Pressure Measurements Project at the Lewis Research Center. This exploratory research project includes flight and ground testing to determine the flight and weather conditions which may lead to altitude misinformation. A secondary objective is to compare the water ingestion resistance of existing static ports with static ports being considered for future aircraft. The flight test portion of this project has begun, and ground tests will be predicated on the results of the flight test.

The captain's altimeter (type E42459 10 113, S/N 115) and the first officer's altimeter (type A40179 10 020, S/N 420), both from N97S, were taken to the manufacturer's facility where a detailed teardown was made. The captain's barometric setting counter was determined to be reading approximately 29.67. The synchrotel reading on a servoed angle position indicator was 3.65°. This was calculated to represent an indication of approximately 568 feet; however, the rotor being measured was free to rotate. The outer and inner drums of the assembly, which were held in proper alignment by light spring tension, were displaced so as to indicate an offset of approximately 600 feet. A small area of paint was missing from the drum at an indicated altitude of approximately 1,250 feet. This mark was very similar in size and location to the drum index, bu there was no paint adhering to the underside of the drum index.

The first officer's altimeter was determined to have been set at a barometric setting between 29.73 and 29.24. The displacement from normal alignment between the outer and inner drum was equivalent to approximately 3,000 feet. No impact marks could be found on the altimeter dial, but a portion of the dial next to the drum window revealed an area, similar in shape to the pointer tip, which had been protected from heat damage evident on the surrounding area. The orientation of the protected area indicated that the needle would have to have been either distorted or dislodged prior to the heat damage in order to mask this area of the dial. The masked area was near the outer dial hash mark indicating "3".

A test program was conducted by the Kollsman Instrument Corporation to determine the effect on an altimeter of (1) a 135° roll about the longitudinal axis of the aircraft and (2) sudden stoppage from impact during a rull. The altimeter, mounted on an aluminum bar, 24 inches from the point of rotation, in a standard instrument panel cutout, was set at 875 feet and 29.67. It was rotated about the offset axis at varying speeds from 18°/second to 90°/second. No significant pointer travel was noted due to rotation. Next, the altimeter was allowed to free fall from various heights to a sudden stop. The stop was adjusted to strike the altimeter housing at the rear, midpoint, and panel on successive drops.

The indicated altitude increased to approximately 1,00 feet on each occasion, and was as high as 1,230 feet on one drop from a height of 10 inches. The test was discontinued at this point to avoid damage to the instrument because the estimated shock valves were approximately 50 g's, and the indicated valve compared favorably with that found on the captain's altimeter drum.

1.16 Other

The Southern Airways DC-9 Operating Manual established the procedures to be followed in their operation of DC-9 aircraft. The nonprecision approach was presented graphically with annotations describing crew actions to be taken at the appropriate times, as follows:

1. Complete in-range checklist 10 minutes prior to estimated time of arrival.
2. Select 15° flaps, extend slats, and slow to appropriate maneuvering speed prior to commencing approach.
3. Commence procedure turn 30 seconds past outer maker (depending on wind).
4. Select 25° flaps, extend gear, complete landing checklist and slow to appropriate maneuvering speed.
5. Over radio fix start descent to MDA, maintain previous maneuvering speed.
6. Select 50° flaps, slows to Vref + 5 knots when runway is sighted.
7. Reduce thrust slowly over threshold to obtain VRef speed, touchdown target is 1,000 feet from threshold.

The Before Landing Final Checklist was described, in part, as follows:

GEAR (Both pilots)	DOWN/3 GREEN DOOR LIGHTS OUT PRESSURE AND QUANTITY NORMAL
500' FLAG SCAN SPEED RATE DESCENT	CHECKED

The Southern Airways DC-9 Flight Manual required the pilot not flying the airplane to make the following callouts during approaches:

1. Any deviation below published transition altitudes.
2. 500' above field elevation and state "No Flags" or "Flags On" as seen on instrument.
3. 100' above minimums
4. At minimums, call out "Minimums—Runway in Sight" or "Minimums—No Runway"
5. Any sink rate of 1,000 feet/minute or more.

The manual also stated that descent rates in excess of 1,00 feet/minute and flat approaches were to be avoided. The procedure for either a missed-approach or a rejected landing was the same:

1. Set takeoff power.
2. Rotate immediately to stop descent (minimum 10°) and simultaneously call flaps 15°.
3. Continue as in normal takeoff.
4. Do not raise gear until climb is established.

The radio altimeter system was described in Southern Airways DC-9 Operating Manual in general terms, including the following, "Two separate radio altimeter systems on the (Dash 31)... are provided to obtain precise altitude information above the ground at the minimum decision (sic) altitude (MDA). This information is essential to the pilot in his decision to land or initiate a go-around maneuver." The chief pilot for Southern Airways testified that this statement was misleading that it was excerpted from the DACO DC-9 manual, and was more applicable to precision approaches over level terrain than to nonprecision approaches of this type. He emphasized that Southern's pilots were cautioned in training against using the radio altimeter as a primary reference. In amplifying their training procedure, he also indicated that the pilots were trained to call out altitudes in terms of m.s.l. except the "hundred above" and "minimums" which were obviously referenced to MDA. The 500-foot flag scan was required on all approaches, whether visual or instrument, and a comprehensive standardization program was conducted. He stated that he was not aware that any company pilots deviated from this practice. He estimated that more than half of the approaches made in their line operation were nonprecision.

On January 12, 1971, Southern Airways issued changes to their DC-9 Operating Manual as follows:

(1) A note was added to the Nonprecision Approach and Landing Diagram stating that, for a short approach where time expiation and MDA for the approach are expected to coincide, flaps may be extended to 50° at the approach fix.

(2) An additional callout at 500 feet above minimum altitude was added.

(3) The discussion of use of the radio altimeter was modified to include a warning that the system was unreliable over hilly or rolling terrain, and should not be used for altitude information.

Southern Airways' authority for charter operations was contained in its Operation Specifications. This authority required that any "off-route" operation by accomplished as prescribed by Part 121 of the Federal Aviation Regulations applicable to supplemental air carriers and commercial operators, and by the exceptions which were contained in their Operations Specifications. The exception applicable to IFR takeoff and landing weather minima required that, when the pilot-in-command was not qualified for the airport, he must use the weather minima and instrument approach procedures prescribed in Part 97 of the Federal Aviation Regulations. The minima established for a localizer approach, by this part of the regulations, were 350 feet and 1 mile. However, the minima specifically established for supplemental air carriers or charter operations at the Tri-State Airport were 412 and 1 mile.

The airport and route qualifications applicable to the charter flight in this instance were stated in Part 121.445 as follows:

"(a) Each supplemental air carrier and commercial operator shall establish in its manual a procedure whereby each pilot who has not flown over a route and into an airport within the preceding 60 days will certify on a form provided by the operator that he has studied and knows the subjects listed in paragraph (b) of this section in regard to the routes and airports into which he is to operate.

"(b) Each qualifying pilot shall show that he has adequate knowledge of the following:

(1) Weather characteristics appropriate to the seasons.

(2) Navigation facilities.

(3) Communication procedures.

(4) Kinds of terrain and obstruction hazards.

(5) Minimum safe flight levels.

(6) Pertinent air traffic control procedures including terminal area, arrival, departure, and holding all kinds of instrument approach procedures.

(7) Congested areas, obstruction, and physical layout of each airport in the terminal area in which the pilot will operate."

In accordance with the company's Operations Manual, when the captain signed the flight release, he certified that he had studied and knew the subjects listed above with regard to the route and airports into which he intended to operate. There was, however, no procedure in the manual to provide for a showing by the captain that he had the requisite knowledge.

The airport and route qualifications applicable to scheduled flights of Southern Airways are contained in Part 121.443. This part contains the above-listed requirements of Part 121.445 and also includes the following:

(1) He must show adequate knowledge of position reporting points and holding procedures. This may be demonstrated in a properly equipped synthetic trainer.

(2) He must make an entry, as a member of the flightcrew, at each regular, provisional, and refueling airport into which he is scheduled to fly. The entry must include a takeoff and a landing, and the qualifying pilot must occupy a seat in the pilot compartment, and must be accompanied by a pilot who is qualified for the airport.

(3) The entry requirements may be waived if the initial entry is made under VFT weather conditions; or if the air carrier shows that such qualifications can be made using approved pictorial means; or if the Administrator is notified that the air carrier intends to operate into an airport near one into which the pilot concerned is currently qualified, and the Administrator finds that such qualification is adequate for the new airport, considering at lease the pilot's familiarity with the layout, surrounding terrain, location of obstacles, and instrument approach and traffic control procedures at the new airport.

The original negotiations between Marshall University and Southern Airways resulted in initial rejection by Southern Airways because of the takeoff weight limitations of their aircraft. The subsequent negotiations resulted in a reduction in the weight of passengers and baggage to be carried from approximately 19,500 pounds to 17,500 pounds, and the charter flight was scheduled. The flight was then offered for bid to the pilots and assigned on the basis of seniority, the same as regularly scheduled flights.

The flight was dispatched initially from Atlanta for the entire charter sequence to Baton Rouge. At Kinston, the captain contacted the dispatcher in Atlanta and an update was accomplished by telephone. Both releases anticipated a landing on a wet runway at Huntington, and the 15 percent additional runway requirement was included in the landing distance computations.

The same aircraft, dispatchers, flight planning services, and supervising personnel were used in the charter operation as in the regularly scheduled service. In addition, a charter coordinator was assigned to assist the flightcrew in administrative matters generally involving ground operations. The coordinator's duties involved supervising and expediting ground operations, arranging for fueling, completing weight and balance forms, etc. In the performance of these duties, he normally communicated directly with the captain shortly before landing. Although he was permitted to enter the cock under these circumstances, he was not authorized to occupy the jumpseat. In this instance, the charter coordinator was in the cockpit during the instrument approach, and discussed the fueling at Huntington. He also commented, "Bet'll be a missed-approach" approximately 16 seconds before impact.
During the investigation, considerable attention was focused on the height of the trees on the hill where initial impact occurred. It was determined by an FAA Runway Obstruction Survey, dated December 1, 1970, that several trees on the hill penetrated the ILS approach surface^[8] and therefore constituted obstructions to air navigation as defined in Part 77, Subpart C, of the Federal Aviation Regulations. However, these standards are used in (1) administering the Federal-Aid Airport Program, (2) transferring property under Section 16 of the Federal Airport Act, (3) providing technical advice in the airport design and development, and (4) imposing requirements for public notice of construction or alteration of structures where notice will promote air safety. The criteria used in the establishment of flight procedures and aircraft operational limitations are contained in Part 97 and the U. S. Standard for Terminal Instrument Approach Procedure (TERPS). Paragraph 954 of TERPS requires that the minimum obstacle clearance in the final approach area^[9] shall be 250 feet for a localizer approach. The trees did not violate this requirement.

A pen recording was made of the outer marker identifier signals as they were recorded in the CVR tape, to assist in locating the flightpath of SOU 932 through the radiation pattern. For the purpose of this evaluation, it was assumed that the receiver sensitivity of the DC-9 was the same as that of the FAA flight-check aircraft. It was also assumed that the identification tone had reached its maximum signal strength when the recorded signal stopped. Based on the calculations, it was determined that the aircraft was approximately 1,850 feet south of the outer marker transmitter when the signal stopped. Any variation in these assumptions would, of necessity, place the aircraft closer to the transmitting antenna than depicted on Attachment 1.

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1. The primary difference between this charter flight and a regularly scheduled flight conducted under the Southern Airways' operating certificate is the applicable landing minima. The Federal Aviation Regulations impose higher landing minima on the pilot of a charter flight, unless he is qualified at the airport and lower minima have been established for the airport in the air carrier's operations specifications. In this instance the normal minima for Runway 11 were increased from 1,240 feet and 1/2-mile to 1,240 feet and 1 mile.
2. All times herein are eastern standard, based on the 24-hour-clock
3. A transcript of pertinent cockpit conversation is included in Appendix D.
4. Minimum Sector Altitude—provides 1,000-foot obstacle clearance within a 25-mile radius of a navigation facility (except localizers without a nondirectional beacon). A sector may not be less than 90° in spread, and the obstacle clearance must also apply in adjacent areas within 4 miles of the sector boundary. All altitudes are mean sea level (m.s.l.) unless otherwise indicated.
5. Minimum Descent Altitude is the lowest altitude to which descent shall be authorized in procedures not using a glide slope. Aircraft are not authorized to descend below the MDA until the runway environment (runway threshold, or approved lighting aids or other markings identifiable with the runway) is in sight and the aircraft is in a position to descend for a normal landing
6. The DC-9-30 aircraft was modified to incorporate a simulated DC-9-10 static system. It was flown at Series 10 VRef +5 knots, with the gear down, 50° flaps, and slate closed, to gather the DC-9-10 data.
7. Landing gear down, slats and flaps extended, and VRef +5 knot
8. Part 77.27(b) defines ILS approach surface as a surface longitudinally centered on the extended centerline of an ILS runway beginning at each end of the primary surface and extending outward and upward at a slope of 50 to 1 for a horizontal distance of 10,000 feet and at a slope of 40 to 1 for an additional 40,000 feet. This surface is the width of the the primary surface at the beginning and expends uniformly to a width of 16,000 feet at a distance of 50,000 feet from the end of the primary surface. The primary surface of Runway 11 was 1,000 feet wide and extended 200 feet beyond the threshold at each end of the runway.
9. Paragraph 930(1) gives the dimensions for the final approach area as 50,000 feet long measured outward along the final approach course from a point 200 feet outward from the runway threshold, and 1,000 feet wide at the point expanding uniformly along the localizer course to a width of 16,000 feet at a point 50,000 feet from the beginning point.