The findings were that the flight penetrated a severe thunderstorm and the ingestion of intense rain and hail caused both engines to fail. The engines suffered internal damage and could not be restarted. The crew had no information on the storms west of Rome, and the captain initially decided, based on his airborne weather radar returns, that the storms were too severe to penetrate. For some reason or because of misinterpretation of the radar display, he changed his mind.

— James Albright

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Updated:

2012-04-20

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Dramatization, from
Air Crash Investigations

The Board determined the probable cause to be the "total and unique loss of thrust from both engines while the aircraft was penetrating an area of severe weather."

Board member Francis McAdams dissented, stating that the majority belief "was merely a statement of what happened rather than an explanation of why." His determination of probable cause is more likely much closer to the mark. "This accident involves the captain's critical decision to penetrate rather than avoid a known area of severe weather. . . . It is obvious that the captain flew a route or directed the FO to fly a route into an area which aircraft should not have entered. Southern Airways, and all air carriers, prohibit flying into convective storms because these types of storms are known to be serious hazards. The primary hazard relates to forces in these storms which can destroy an aircraft structurally; however, other hazards exist which are not well defined. . . . The loss of thrust . . . might have been unusual . . . but should not be considered entirely unexpected, given the multiple hazards associated with flight into severe convective storms."

There used to be more art than science when it came to reading airborne radar. The old monochromatic radars did not portray varying intensities as well as a modern color radar and were even more susceptible to attenuation. Without the proper training, pilots today can just as easily misread a clear spot on a radar scope to be a sign of clear skies when in fact it is the classic "blind alley." The lesson learned is never fly into a radar shadow. For more about this, refer to Radar Techniques..

1 — Accident report

2 — Narrative

3 — Analysis

4 — Cause

5 — Postscript

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1

Accident report

  • Date: 04 APR 1977
  • Time: 16:19 EST
  • Type: McDonnell Douglas DC-9-31
  • Operator: Southern Airways
  • Registration: N1335U
  • Fatalities: 2 of 4 crew, 61 of 81 passengers
  • Aircraft Fate: Destroyed
  • Phase: En route
  • Airports: (Departure) Huntsville-Madison County Airport, AL (HSV/KHSV), United States of America ; (Destination) Atlanta Municipal Airport, GA (ATL/KATL), United States of America

2

Narrative

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"There's a hole,"
Dramatization, from
Air Crash Investigations

  • At 1554:35, Flight 242 established communications with Huntsville departure control and at 1554:39, the controller cleared the flight to proceed directly to the Rome VOR. According to the cockpit voice recorder (CVR), at 1555:58 the captain remarked, "Well the radar is full of it, take your pick." At 1556:00, the controller told Flight 242 that his radarscope was showing heavy precipitation and that the echos were about 5 nmi ahead of the flight. Flight 242 responded, "Okay . . . we're in the rain right now . . . it doesn't look much heavier that what we're in, does it?" At 1556:12, the controller said, ". . . I got weather cutting devices on which is cutting out the precip that you're in now . . . however it's not a solid mass, it . . . appears to be a little bit heavier than what you're in right now." Flight 242 replied, "Okay, thank you."
  • At 1556:37, the first officer, who was flying the airplane, said, "I can't read that, it just looks like rain, Bill. What do you think? There's a hole." The captain responded, "there's a hole right here. That's all I see." He added, "Then coming over, we had pretty good radar. I believe right straight ahead . . . there's the next few miles is about the best way we can go."
  • At 1557:36, the controller said, ". . . you're in what appears to be about the heaviest part of it right now, what are your flight conditions?" Flight 242 replied, ". . . we're getting a little light turbulence and . . . I'd say moderate rain. . . " At 1557:47, the controller acknowledged Flight 242's report and told the flight to contact Memphis Center.
  • At 1558:10, Flight 242 established communications with Memphis Air Route Traffic Control Center (Memphis Center). At 1558:32, the captain said, "As long as it doesn't get any heavier we'll be all right." The first officer replied, "Yeah, this is good."
  • At 1558:26, the Memphis Center controller advised the flight that a SIGMET was current for the vicinity of Tennessee, southeastern Louisiana, Mississippi, northern and western Alabama, and adjacent coastal waters, and advised them to monitor VOR broadcasts within a 150-nmi radius of the SIGMET area. At 1558:45, the controller told Flight 242 to contact Atlanta Air Route Traffic Control Center (Atlanta Center). At 1559:00, the captain said, "Here we go ... hold 'em cowboy."
  • At 1559:06, Flight 242 established communications with Atlanta Center (Sector 39) and stated that it was "out of eleven for seventeen." The controller replied, "...roger, expect Rome runway 26 profile descent." Flight 242 acknowledged the controller's transmission. Between 1559:18 and 1602:03, the Atlanta Center controller conversed with TWA Flight 584 about its deviations eastward around thunderstorms between Chattanooga, Tennessee, and Rome, Georgia. At 1600:30, the sound of rain was recorded on Flight 242's CVR. At 1602:57, the captain of Flight 242 said, "I think we'd better slow it up right here in this..." The first officer replied, "Got ya covered."
  • At 1603:01, an Atlanta Center controller (sector 40) contacted an Eastern Airlines flight, which had just crossed the storm area northwest of Rome, and asked, "How would you classify your ride through that line up there? You recommend anyone else come through it?" The flight answered that "it was not too comfortable but we didn't get into anything we would consider the least bit hazardous." At 1603, Flight 242 was told to contact Atlanta Center (sector 40). About 11 sec later, the sound of light rain was recorded on the CVR. At 1603:20, Flight 242 established communications with Atlanta Center on the new frequency and said, "...level at seventeen." At 1603:48, the captain said, "Looks heavy, nothing's going through that." Six secs later, he said, "See that." The first officer said, "That's a hole, isn't it?" The captain replied, "It's not showing a hole, see it?" At 1604:05, the sound of rain was recorded on the CVR, and 3 sec later the first officer asked, "Do you want to go around that right now?" At 1604:19, the captain said, "Hand fly it about 285 knots," and the first officer responded, "285."
  • At 16-4:30, the sounds of rain and hail were recorded, and 20 sec later Flight 242 reported to Atlanta Center that the flight was reducing speed. At 1605:53 the first officer said, "Which way do we go cross here or go out--1 don't know how we get through there, Bill." The captain replied, "I know you're just gonna have to go out..." The first officer said, "Yeah, right across that band." At 1606:01 the captain said, "All clear left approximately right now; I think we can cut across there now." At 1606:12, the first officer right, here we go."
  • Between 1604:42 and 1606:20, Atlanta Center was coordinating with TWA 584 about its route and altitude to intercept the Atlanta VOR 313" radial inbound. At 1606:30 the controller said, "I show weather up northwest of that position, north of Rome, just on the edge of it . . . maintain 15,000." TWA 584 replied, "Maintain 15,000, we paint pretty good weather at 1 or 2 o'clock."
  • At 1606:41, the first officer on Flight 242 said, "He's got to be right through that hole about now." About the same time, Atlanta Center cleared Flight 242 to descend to and maintain 14,000 ft. At 1606:46, the captain said, "Who's that?" and the first officer replied, "TWA." At 1606:53, the captain reported to Atlanta Center, "242 down to 14." About the same time, the sound of heavy hail or rain was recorded on the CVR. The sounds continued to 1607:57, at which time the CVR ceased to record for 36 sec; it began operation again at and the sound continued for another 40 sec.
  • Between 1607:00 and about 1608:01, Atlanta Center made four transmissions to Flight 242; none was acknowledged. About 1608:34, Atlanta Center said, "Southern 242, Atlanta." At 1608:42, the first officer said, "Got it, got it back Bill, got it back." At 1608:49, Flight 242 told Atlanta Center to "standby." At 1608:49, Atlanta Center transmitted, "Roger, maintain 15,000 if you understand me, maintain 15,000, Southern 242." at 1608:55, Flight 242 replied, "We're trying to get it up there."
  • At 1609:15, Flight 242 reported to Atlanta Center, "Okay . . . we just got our windshield busted and . . . we'll try to get it back up to 15, we're 14." At 1609:36, the first officer said, "Left engine won't spool," and Flight 242 reported to Atlanta Center, "Our left engine just cut out." Atlanta Center replied, ". . . roger, and lost your transponder, squawk 5623." At 1609:43, the first officer said, "I'm squawking 5623, tell him I'm level 14."
  • At 1609:59, the captain said, "Autopilot off," and the first officer replied, "I got it, I'll hand fly it." At 1610:00, Atlanta Center cleared Flight 242 to descend to 13,000 ft. At 1610:04, the first officer said, "My . . . the other engine's going too . . . .," and at 1610:05, Flight 242 reported to Atlanta Center, ". . . the other engines going too." Atlanta Center replied, ". . . say again." Flight 242 said, "Standby, we lost both engines."
  • At 1610:14, the first officer said, "All right Bill, get us a vector to a clear area." At 1610:16, Flight 242 told Atlanta Center, "Get us a vector to a clear area Atlanta." Atlanta Center replied, ". . . continue present southeast-bound heading. TWA's off to your left about 14 mi at 14,000 and says he's in the clear." Flight 242 replied, "Okay."
  • At 1610:27, Flight 242 asked Atlanta Center, "Want us to turn left?" Center replied, ". . . contact approach control 126.9 and they'll try to get you straight into Dobbins." At 1610:36, the first officer said, "Give me -- I'm familiar with Dobbins, tell them to give me a vector to Dobbins if they're clear." At 1610:38, Flight 242 asked Atlanta Center, "Give me a vector to Dobbins if they're clear." The Center replied, ". . . 126.9, they'll give you a vector to Dobbins." At 1610:45, Flight 242 replied, "269, Okay."
  • At 1610:50, the first officer said, "Ignition override, it's gotta work. . . ." At 1610:52, an Atlanta Approach Control transmission to Lear Jet 999M was recorded on Flight 242's CVR; at 1610:56, the CFR ceased operation for 2 min 4 sec. Between about 1611:17 and 1612:50, Atlanta Center made three transmissions to Flight 242. About 1612:00, Atlanta Approach Control made one transmission to Flight 242; 10 sec later, TWA 584 called Flight 242. No responses were recorded.
  • At 1613:00, the CVR resumed operation, and at 1613:03 the captain said, "There we go." The first officer responded, "Get us a vector to Dobbins." At 1613:04, Flight 242 transmitted to Atlanta Approach Control, ". . . Atlanta, you read Southern 242?" Approach Control replied, "Southern 242, Atlanta . . . go ahead." Flight 242 said, ". . . we've lost both engine, how about giving us a vector to the nearest place. We're at 7,000 ft." At 1613:17, Approach Control replied, "Southern 242, roger, turn right heading 100°, will be vectors to Dobbins for a straight-in approach runway 11 . . . your position is 15, correction 20 mi of Dobbins at this time." Concurrent with this transmission, the first officer said, "What's Dobbins' weather, Bill? How far is it?" Flight 242 transmitted, "Okay 140° heading and 20 mi."
  • At 1613:35, Atlanta Approach Control directed, ". . . make a heading of 120, Southern 242, right turn to 120°." Flight 242 replied, ". . . okay, right turn to 120 and . . . you got us our squawk, haven't you." Concurrent with this transmission, the first officer said, "Declare an emergency, Bill." At 1613:45, Approach Control replied, "I'm not receiving it, but radar contact, your position is 20 mi west of Dobbins." Flight 242 replied, "Okay."
  • At 1614:02, first officer said, "Get those engines . . ." At 1614:24, Flight 242 transmitted to Approach Control, "All right, listen, we've lost both engines, and . . . I can't tell you the implications of this . . . we . . . only got two engines, and how far is Dobbins now?" Approach Control replied, ". . . 19 mi." Flight 242 transmitted, "Okay, we're out of 5,800, 200 kns." At 1614:45, Approach Control asked, "Southern 242, do you have one engine running now?" Flight 242 replied, "Negative, no engines."
  • At 1615:04, the captain said, "Just don't stall this thing out." The first officer replied, "no I won't.'' The captain said, "Get your wing flaps," and the sound of lever movement was recorded. At 1615:11, the first officer said, "Got it, got hydraulics, so we got." The captain replied, "We got hydraulics." At 1615:17, the first officer said "What's the Dobbins weather?" At 1615:18, Flight 242 asked Approach Control, "What's your Dobbins weather?" Approach Control said, "Standby." At 1615:46, Approach Control said, "Southern 242, Dobbins weather is 2,000 scattered, estimated 7,000 overcast, visibility 7 mi." Flight 242 replied, "Okay, we're down to 4,600 now." Approach Control responded, "Roger, and you're approximately ... 17 mi west of Dobbins at this time. " At 1616:05, Flight 242 said, "I don't know whether we can make that or not.""
  • At 1616:11, the first officer said, "...ask him if there is anything between here and Dobbins?" The captain said, "What?" and the first officer repeated his request. At 1616:25, Flight 242 asked Approach Control, ". . .is there any airport between our position and Dobbins?" Approach Control replied, "...no sir, closest airport is Dobbins." At 1616:34, Flight 242 said, "I doubt we're going to make it, but we're trying everything to get something started. " Approach Control replied, "Roger, well there is Cartersville, you're approximately 10 mi south of Cartersville, 15 mi west of Dobbins."
  • At 1616:45, Flight 242 asked Approach Control, "Can you give us a vector to Cartersville?" Approach Control replied, "All right, turn left, heading of 360, be directly ... direct vector to Cartersville." Flight 242 said, "360, roger." At 1616:53, Flight 242 asked Approach Control, "What's the runway heading?" Approach Control replied, "Standby." Flight 242 then asked, "And how long is it?" Approach Control replied, "Standby."
  • At 1617:08, the captain said, "...I'm picking out a clear field." The first officer replied, "Bill, you've got to find me a highway." The captain said, "Let's get the next clear open field." The first officer said, "No . . ." At 1617:35, the captain said, "See a highway over -- not cars." The first officer said, "Right there, is that straight?" The captain replied, "No." The first officer said, "We'll have to take it."
  • At 1617:44, Approach Control transmitted, "Southern 242, the runway configuration ... at Cartersville is . . . 360 and running north and south and the elevation is 756 ft, and. ..trying to get the length now -- it's 3,200 ft long." At 1618.02, Flight 242's last transmission to Approach Control was recorded: "...we're putting it on the highway, we're down to nothing." From 1618:36 to 1618:43, crash sounds were recorded on the CVR.

Source: NTSB AAR 78-30, §1


3

Analysis

  • N1335U was equipped with a Bendix model RDR-18 weather radar system. The system operated on X-band frequency at a 3.2 cm wave-length. The system could display targets at three range selections--30 mi, 80 mi, and 180 mi. The system was designed to display weather in two modes--normal and contour. In the normal mode, precipitation is as luminescent areas on the dark background of the cockpit indicator. In the contour mode, the areas of heavy precipitation are electronically eliminated to produce a dark hole (contour hole) surrounded by the luminescent areas of lighter precipitation. According to the manufacturer, in the contour mode, areas of precipitation that exceed a reflectivity factor of log Z (which is equivalent to a rainfall rate of 0.5 1.0 in. per hour) would appear as contour holes. According to the manufacturer's operating manual for pilots which was used by Southern Airways as a flightcrew training guide, contour holes should definitely be avoided by at least 10 mi. Additionally, any weather displayed beyond a range of 75 mi indicates areas of significant rainfall, regardless of the presence or absence of contour holes, and should be avoided. The manual recommended that flights detour around weather as soon as possible and that the pilot avoid late detours around a particular target at close range.

Source: NTSB AAR 78-30, §1.17

Weather

  • From an evaluation of all the evidence, the Safety Board concludes that the causal factors related to this accident are associated with the severe weather conditions that Flight 242 encountered near Rome, Georgia, the extent of the flightcrew's knowledge of those conditions before the encounter, and the information about those conditions provided to the flightcrew. After the severe weather conditions were encountered and thrust from the engines was completely and permanently lost, and accident most probably was inevitable.
  • Although the intensity of the rain and hail is not known, the Safety Board concludes that the intensity was sufficient to cause rotational speed of the engines to decrease below that required for operation of the engine-driven generators.
  • If the thrust levers remained at relatively high thrust setting after the compressors were damaged, high fuel flow in conjunction with reduced compressor efficiency would cause over temperatures in the turbine sections of the engines. The damage to the turbine sections of both engines clearly indicates over temperatures before the engines quit.

Source: NTSB AAR 78-30, §2

Dobbins

  • Although the Safety Board concludes that, after complete failure of the engines, an accident was most probably inevitable, we believe that had the flight continued toward Dobbins Air Force Base, the flightcrew's chances of successfully landing the aircraft on the 10,000-ft runway would have been significantly greater than their chances with any other available option.

Source: NTSB AAR 78-30, §2

Captain not taking control

  • Standard operating procedures and practices dictate that a captain take control of the aircraft in an emergency situation. It could not be determined why the captain did not take over control at least in the final stages of the emergency landing.

Source: NTSB AAR 78-30, §1


4

Cause

The National Transportation Safety Board determines that the probable cause of this accident was the total and unique loss of thrust from both engines while the aircraft was penetrating an area of severe thunderstorms. The loss of thrust was caused by the ingestion of massive amounts of water and hail which, in combination with thrust lever movement, induced severe stalling in and major damage to the engine compressors.

Major contributing factors include the failure of the company's dispatching system to provide the flight crew with up-to-date severe weather information pertaining to the aircraft's intended route of flight, the captain's reliance on airborne weather radar for penetration of thunderstorm areas, and limitations in the FAA's ATC system which precluded the timely dissemination of real-time hazardous weather information to the flight crew.

Source: NTSB AAR 78-30, §3.2

References

(Source material)

May Day: Southern Storm, Cineflix, Episode 41, Season 5, No. 6, 23 April 2008

NTSB Aircraft Accident Report, AAR-78-3, Southern Airways Inc., DC-9-31, N1335U, New Hope, Georgia, April 4, 1977