CA-234

CA-234 File No: 1-0024

CIVIL AERONAUTICS BOARD

ACCIDENT INVESTIGATION REPORT

Adopted: October 15, 1951 Released: October 22, 1951

UNITED AIR LINES, INC., FORT WAYNE, INDIANA, APRIL 28, 1951

THE ACCIDENT

At approximately 1932, 1 April 28, 1951, United Air Lines' Flight 129, a Douglas DC-3, A-16088, crashed and burned 2 6 miles east-southeast of Baer Field, Fort Wayne, Indiana The eleven occupants were killed and the aircraft was demolished

HISTORY OF THE FLIGHT

Flight 129 departed Cleveland, Chic, at 1807, April 28, 1951, for Chicago, Illinois, with stops scheduled at Fort Wayne and South Bend, Indiana The crew consisted of Captain E K Swallow, First Officer H R Miller, and Stewardess Beverly Fllis, there were eight passengers on board at the time of departure The aircraft weighed 24,180 pounds, which was within the certificated gross weight limit of 25,320 pounds, and the load was properly distributed A flight plan filed by the crew with ARTC (Air Route Traffic Control) indicated an IFR (instrument flight rule) flight at a cruising altitude of 4,000 feet with South Bend and Toledo, Ohio, designated as the alternate airports The "Trip Weather Analysis" (a form prepared by the crew before departure) indicated that scattered cumulus and thunderstorms were expected south of the course to Fort Wayne Also, that a squall line extending in a north-south direction was moving eastward across Illinois and Indiana at an estimated speed of 35 miles per hour and was expected to be in the vicinity of South bend upon the flight's arrival there

After takeoff, Flight 129 was advised by company radio that it was cleared by ARTC via Green Airway No 3 over Sandusky, Ohio, to the Toledo range, to maintain 3,000 feet and to contact Toledo approach control upon arriving there Flight 129 advised they were going to Fort Wayne and not Toledo Accordingly, ARTC amended the flight's clearance to proceed to Fort Wayne via Green Airway No 3 and Blue Airway No 44 and to maintain 4,000 feet The flight proceeded and a routine company radio report was made when over Sandusky At 1847, the flight reported over Toledo and estimated its arrival Fort Wayne at 1932 At this time, the Fort Wayne 1830 weather sequence report was given the flight which was, "ceiling estimated 25,000 feet, thin Broken clouds, visibility 0 miles, wind southwest 5 miles per hours "Seventeen minutes later at 190', flight 129 called Toledo tower and requested, through APTC permission to cruise at 2,300 feet because of turbulent conditions This was not approved because of other traffic At 1920 the flight reported it was approaching Fort Wayne and was changing to tower frequency The flight reported again when nineteen in less northeast of Bauer Field and was advised at Runway 22 was the runway in use and that the wind was five to ten miles per hour from the southwest At the time this transmission was made there was a moderate amount of station and the flight reported "We are not recanting you very clearly but I think you said, `Straight 11 runway 22' We will call later, closer in "

Because of thunderstorm activity in the area, three other aircraft were requesting instructions to land at approximately the time Flight 129 was making its approach Two of these aircraft landed successfully and the pilot of one, upon request, advisee the tower that the thunderstorm was approximately ten miles west of the airport

At the time the four aircraft were approaching Baer Field, United *** 12 degrees was number four to land in the traffic pattern immediately behind *** World Airlines' Flight 240, a DC-3 aircraft then these latter aircraft were approximately one and two and one-half miles, respectively, from the approach end of Runway 22, the wind at the airport shifted to west-northwest and increased in velocity from 5-10 miles per hour to 40 miles per hour Both flights were advised by the tower of the sudden change of wind direction and increased velocity, and a landing on Runway 27 was suggested, it being more nearly into the wind Upon receiving this message the flights immediately turned to the left to align with this runway

When these aircraft were east of the airport the wind increased to 60-65 miles per hour with gusts to 85 miles per hour and a heavy rainfall began, accompanied by lightning and severe static The flights were quickly advised of the weather change but, due to the sudden decrease in visibility, neither flight was seen again by the tower Flight 129 immediately advised, "United 129 heading east" This was closely followed by a message from TWA's 240, "Pulling out" In order to avoid a possible collision the tower then requested separation altitudes for these aircraft from Chicago ARTC and was advised that Flight 129 was assigned an altitude of 4,000 feet and that Flight 240 was assigned 3,000 feet Both clearances were broadcast from the tower several times without acknowledgment

At 1932 m orange-colored flash was seen to the east-southeast from the tower It was later determined that United's Flight 129 had crashed in a field 2 6 miles east-southeast of the airport TWA's Flight 240 proceeded safely to Toledo

INVESTIGATION

Investigation disclosed that N-16088 was flying on an approximate heading of 120 degrees when it struck the ground and that at the time of impact it was in a near level attitude with the left wing slightly low Initial ground contact was made by the aircraft's left wing tip Wreckage was strewn over the ground a distance of 720 feet and the main wreckage came to rest in a wooded area several hundred feet distant from the point of initial impact 2

A detailed examination of the wreckage revealed no evidence of fire, structural failure, or mechanical malfunction of any part of the aircraft or its ***prior to impact The damage pattern to all propeller blades in the form of comp and Bends, severe nicks and gouges in the leading cages near the tips, together with the blade angle positions, indicated that considerable power was being produced by both engines when impact occurred

All instruments in the pilot's cockpit were damaged in such a manner that they were unreadable

The aircraft's records were examined and these indicated that the aircraft was *** worthy on departing Cleveland

On April 28, 1951, the 1530 *** weather map prepared by the U S Weather Bureau showed an extensive high pressure cell lying off the Atlantic Coast with a moderate gradient extending through Ohio, Illinois, and Iowa A cold front extended form Lake Huron in a southwesterly direction across northern Michigan and Lake Michigan to Milwaukee, Wisconsin, where it Joined a stationary front extending across south-eastern Wisconsin, northwestern Illinois, and Iowa A squall line 3 was charted in a north-south direction across the extreme western part of Illinois Over Illinois and Indiana winds aloft between the 11,000 and 16,000-foot levels were blowing form west-southwest to west at approximately 30 knots

The U S Weather Bureau first forecast the movement of the squall line to be at the rate of 30 miles per hour At 1713, an hour before it was forecast to arrive there the squall line reached Chicago The Weather Bureau then amended its forecast to indicate the forward movement of the storm to be 40 miles per hour and reported severe turbulence in the storm area over northern Illinois A Chicago special weather sequence report, at 1719, reported a thunderstorm accompanied by heavy hail and wind from the north-northwest at 42 miles per hour with gusts to 57 miles per hour At 1831, the storm reached South Bend and was reported as being heavy with small hail and wind from the west-northwest at 35 miles per hour with gusts to 55 miles per hour Two pilots attempted penetrate the storm in the vicinity of North Liberty and Goshen, Indiana, but decided it was inadvisable to do so and returned to Fort Wayne

Several tornadoes were reported along the squall line, three were plotted as beginning near the Indiana-Ohio state border and extending eastward One of these tornadoes, in its formative stage, was a short distance east of the scene of the accident No evidence of tornado damage could be found along the flight path, of the subject aircraft

Large hailstones were reported falling near the scene of the accident, however, it was determined that hail did not fall in this area until after the crash occurred

Neither the company meteorologist nor the Weather bureau anticipated the rapid movement of the storm or its severity in the Fort Wayne area Investigation revealed that the storm progressed along northern Indiana at a rate averaging in excess of 60 miles per hour instead of the 40 miles per hour previously forecast It took approximately five minutes, only, for the storm to arrive over Baer Field after it had been reported as being 10 miles distant This indicated that the location of the storm was inaccurately reported since, to travel this distance in the time given, the storm would have moved at a rate far in excess of its known speed

The pilot of TWA's Flight 240 stated that when he was approaching the airport and was

advised of the accelerated wind with gusts to 85 miles per hour, he immediately executed a left turn and proceeded to Toledo, also that little or no turbulence was experienced during this portion of the flight It should be noted that Flight 240 turned immediately ahead of and avoided the approaching storm,

but that Flight 129 was caught in the storm during the turn 4 The few seconds in time and the short distance separating Flight 240 from the subject aircraft meant the difference between flying through reasonably stable air or severe down drafts and turbulence

ANALYSIS

A down draft is composed of cool relatively dense air It is logical to assume that practically all initial down drafts descend to the ground, then start fanning out, proceeding ahead of the storm by means of horizontal flow Thereafter, down drafts in new cloud developments along the forward edge of the storm lose most of their downward velocity before reaching the ground It is for that reason that a plane caught in a down draft usually can recover before being carried dangerously close to the ground In the case of the squall line at Fort Wayne the prorogation of the storm was so rapid on the forward side that it resulted in an increased movement of the squall line amounting to 30 miles per hour or more As a consequence, the fanning out process never had time to form an outflow ahead of the storm and new down draft descended to the ground because of the lack of the cushioning effect Although there is evidence to indicate that a tornado was in its initial stage of development near the scene of the accident, it is unlikely that it caused the aircraft to crash The forces which accompany even an incipient tornado would be different in character than those which forced this aircraft to the ground Had such forces been associated with this accident it is extremely doubtful that lateral control of the aircraft could have been maintained Since the testimony of witnesses who saw the aircraft in flight does not indicate loss of lateral control and the aircraft struck the ground in a near level altitude and with power on, it can reasonably be assumed that a severe down draft was encountered on the edge of the storm from which there was insufficient altitude to recover Down drafts of such magnitude are frequently a part of a line squall development but do not usually occur so close to the ground

Referring to Appendix B, the eastward movement of the forward edge of the squall line is shown in one-half minute intervals by means of dotted lines The path of TWA's Flight 240 is shown by a dashed line with time locations noted It is seen that at all times this flight was ahead of the squall line, but by a very narrow margin of less than a mile during d portion of the turn The solid line on the chart indicates the flight path of UAL's 129 with time locations This also shows that at 1931 1/2, the flight had penetrated the forward edge of the squall line and was still at that relative position at the time of the crash

FINDINGS

On the basis of all available evidence, the Board finds that

The aircraft, the crew, and the company were properly certificated

The squall line moved across northern Illinois and northern Indiana considerably faster than was forecast

A line of thunderstorms was known to be approaching Fort Wayne However, it was believed that aircraft in the area could effect safe landings prior to the storm's arrival there

When the subject flight and another were approaching Runway 27, they were advised of the surface wind's increased velocity to 65 miles per hour with gusts to 85 miles per hour

When the approach was abandoned the aircraft encountered the forward edge of the squall line and was subjected to a severe down draft from which recovery could not be made

PROBABLE CAUSE

The Board determines that the probable cause of the accident was the severe down draft encountered which caused the aircraft to strike the ground in a near level attitude

BY THE CIVIL AERONAUTICS BOARD

/s/

Donald W Nyrop

/s/

Oswald Ryan

/s/

Josh Lee

/s/

Joseph P Adams

/s/

Chan Gurney

Supplemental Data

INVESTIGATION AND HEARING

The Civil Aeronautics Board received notification of the accident at 2035, April 28, 1951, from Civil Aeronautics Communications at Chicago, Illinois An investigation was immediately initiated in accordance with the provisions of Section 702 (a) (2) of the Civil Aeronautics Act of 1938, as amended As part of the investigation, a public hearing was held on May 10, 1951, at Fort Wayne, Indiana

AIR CARRIER

United Air Lines, Inc , is a corporation organized and existing under the laws of the State of Delaware, having its principal office at 5959 South Cicero Avenue, Chicago, Illinois It holds a certificate of public convenience and necessity issued by the Civil Aeronautics Board authorizing the carriage of passengers and mail over a number of routes in the United States, including transcontinental route No 1 from California to New York It also holds an air carrier operating certificate issued by the Administrator of Civil Aeronautics

FLIGHT PERSONNEL

Captain Eugene K Swallow, age 31, was employed by United Air Lines December 18, 1941 He had accumulated 6,827 flying hours, of which 5,694 were on DC-3 type equipment He held a currently effective airline transport rating No 33025-40 with appropriate ratings His last instrument check was accomplished December 31, 1950, and route check August 28, 1950 His last CAA physical examination was accomplished February 19, 1951

First Officer Herman R Miller, age 24, was employed by United Air Lines February 7, 1951 He had accumulated a total of 1,121 hours, of which 121 hours were on DC-3 type equipment He held a valid airman certificate with commercial and instrument ratings His last CAA physical examination was accomplished January 29, 1951

THE AIRCRAFT

N-16088, a Douglas DC-3, was manufactured March 1937 It had accumulated a total aircraft flying time of 43,550 hours Its last aircraft overhaul was accomplished April 5, 1951 It was equipped with two Pratt & Whitney Model R-1830-92 engines Both engines had accumulated a total of 151 54 hours since last overhaul The engines were equipped with Hamilton Standard hydromatic propellers

APPENDIX A

SHEET 1

Figure

"WRECKAGE DISTRIBUTION CHART 1"

AIRCRAFT

ACCIDENT

UAL DC-3

N 16088

FORT WAYNE,

INDIANA

APPENDIX A

SHEET 2

Figure

"WRECKAGE DISTRIBUTION CHART 1"

AIRCRAFT

ACCIDENT

UAL DC-3

N 16088

FORT WAYNE,

INDIANA

APPENDIX A

SHEET 3

SHEET NUMBER 3 OF 3

Figure

Appendix B

FOOT NOTE

1 All times referred to herein are Central Standard and based on the 24-hour clock

See Appendix A

A squall line consists of a series of connected thunderstorm cells which are continually building up on their forward side and dissipating on the rearward side

The probable flight paths of the aircraft with respect to time and position relative to the storm are shown in Appendix B