![]() |
?Home
?Aircraft
?History
?Accidents
?Multimedia
?Memorabilia |
Accident
Investigation Report The
Accident
History
of the Flight
An
examination was made of the fluorescent lights after the landing. They appeared
to operate normally, so the flight departed from Brussels, continuing without
difficulty until on the final landing approach into London. When the power was
reduced the same pilot’s fluorescent lights again went out. This time the chart
light was focused on the airspeed indicator. The approach was continued, and the
landing was accomplished without incident. A
faulty rheostat switch was found to be the cause of the fluorescent light
failure; but since a spare switch could not be located, it was not changed at
London. An entry describing the defect was placed in the aircraft’s Form C, the
airplane flight log, and the captain and the flight engineer of the new crew
were informed by the company’s maintenance supervisor of the condition. Though
no actual maintenance was accomplished, the lights again appeared to be
operating normally, so the captain, F. C. Jakel, decided to take-off, departing
from London at 0035, April 15, 1948, for Shannon. At this time available weather
forecasts indicated that at the estimated time of the flight’s arrival at
Shannon the ceiling there would be 700 feet with a higher cloud layer at 1,000
feet, and visibility 4 miles. At
0159, April 15, 1948, the flight reported being at an altitude of 4,500 feet,
contact, over the Limerick Junction fan marker, located 25 statute miles
southeast from the Shannon Airport, and requested permission to make a practice
approach to the field with the use of the instrument landing system. Shannon
Tower cleared the flight for this approach. The tower advised that 3 hours
previously the instrument landing system equipment on the airport had been
reported faulty, but that it had since been serviced and was operating normally
according to its monitoring board, though not flight-checked. At
0210, the flight reported that it was proceeding to the outer marker, 5.2
statute miles northeast of the Shannon Airport, and also made a report, routine
for Pan American flights, Mechanical condition okay." In response Shannon
Tower advised the flight that the weather over the field was: fog patches, 3
miles visibility, cloud base 400 feet, sky 6/10 covered wind from 325 degrees at
4 miles-per hour." The flight was instructed to land on runway 23, the
runway for which the instrument landing system was projected. It was also
requested to report when making the 180 degree procedure turn for the inbound
instrument approach to the field, and when over the outer marker. The requested
position reports were not received by the tower, but at 0220 the flight did
report a "missed approach," and advised that it was going around for a
second approach. At this time the flight was observed through a break in the
clouds by the Shannon Tower, which was the first time that the aircraft had been
seen in the vicinity of the Shannon Airport. The aircraft was reported as 500
feet above the ground, over, and in line with runway 23. ‘ Power was heard being
increased, and the aircraft was observed turning left. ‘ On
the second approach, at 0227, the flight reported making its 180 degree
procedure turn and was cleared for landing by the tower. One minute later,
weather conditions at the field were transmitted to the flight as: fog patches,
visibility 2 1/2 miles 6/10 cloud base 400 feet 4/10 cloud base 300 feet, wind
325 degrees, 3 miles per hour, altimeter 30.29." The flight reported
approaching the outer marker at 0231 at which time the tower advised that
another flight which had just taken off had reported a ceiling of 500 feet when
northwest of the field. Flight 1-10 acknowledged this information, which was the
last communication received. The aircraft was not observed at any time during
the second approach until after it struck the ground. The
aircraft struck the ground 2,380 feet northeast of the approach end of runway
23, and directly in line with that runway. Flames followed immediately after
impact, and consumed a great portion of the wreckage. The
sole survivor, a representative of ‘the Lockheed Aircraft Service, Inc., skated
in the cabin at a location slightly behind the trailing edge of the right wing,
stated that on the first approach all engines seemed to be operating normally,
and no unusual maneuvering of the aircraft was experienced. He stated that he
did not observe the runway lights and other field lighting until the aircraft
was directly over the field. The altitude of the aircraft appeared too high to
him for the landing, and he heard power being applied to the engines for the
pull up. According
to this passenger, the engines seemed to be operating normally also during the
second approach. The "fasten seat belt no smoking" sign was on. He
heard the flaps extend, and observed that the flight attitude was normal. He
stated that the first contact with the ground felt as though the airplane had
made a hard landing on the runway. Immediately following, however, severe jolts
were felt; and flames swept through the cabin from the forward part of the
fuselage. He then realized that the airplane had crashed. He had been thrown
forward in his seat but was saved from injury by his safety belt. When the
aircraft stopped, he noticed that though filled with flames the cabin remained
substantially undamaged; and that all passengers were in their seats, but made
no sound or movement. He said that he did not believe himself physically or
mentally capable of opening any of the emergency exits, so he crawled toward the
rear of the cabin, and dropped through a large tear in the fuselage to the
ground. Investigation
Marks
on the ground made by the propellers indicated that at impact all had been
rotating with normal glide power. The governor for the No. 1 propeller was
bench-checked and found to be set at 2300 revolutions per minute. The distance
between the individual blade marks for propellers Nos. 1, 2, and 3 were all
about 38 inches apart. Forward speed of the aircraft was calculated to be
approximately 108 miles per hour. Since considerable deceleration probably
occurred before the propeller blades marked the ground, the speed of the
aircraft on final approach before first impact was substantially greater. All
evidence found and the statement of the surviving passenger indicated that all
engines were operating normally during the approach. An examination of the
cockpit controls and instruments was impossible because of complete fire
destruction; however, no indication was found that other than normal operation
was experienced before the crash. Likewise, the almost complete destruction of
the airborne radio equipment made it impossible to determine its operational
status prior to the accident, but all communications between the flight and the
tower were made without any difficulty. A
complete examination of the records of Shannon Airport revealed that the radio
range and instrument landing system equipment were operating normally at the
time of the accident. A ground and flight check of all the instrument landing
system equipment was accomplished after the crash, which included checking the
localizer and glide path, the outer, middle, and inner markers, and the compass
locators. The operation of the complete system was found normal. Various types
of failures were simulated and the monitoring equipment was found to give
adequate indication of malfunctioning within the 70 second cycle which was
required for one complete scan of the alarm circuit. The
ground control approach (GCA) equipment at Shannon Airport was not operating at
the time of the accident. Shannon Airport, however, is completely equipped with
the necessary radar equipment for ground control approach. At the time of the
accident this equipment was being used only during hours of daylight to train
ground personnel. Runway
23 at Shannon Airports for which the instrument landing system was projected, is
7,000 feet long and 220 feet wide. Though the Bartow lights on the runway were
on at the time of the accident, the installation of Bartow approach lights to
the runway had not been completed and were not operating. Terrain northeast of
runway 23 consists of low rocky hills, covered with brush, trees and stone
fences. Elevation at the point of impact was 12 feet above runway 23. Captain
F. C. Jakel had logged a total of 6,230 flying hours, of which 1,564 were in
Constellations. He had completed the Pan American training course offered for
familiarization with the instrument landing system. This course included 2 hours
of link trainer time, and 4 hours of actual practice in an airplane. Captain
Jakel after the completion of this training was also given refresher training.
He was considered a competent pilot by the company and was familiar with the
airport and surrounding area at Shannon, Eire. A
synoptic surface weather chart prepared in the London Meteorological Office, at
2100, April 14, 1948, showed that a high pressure area extended northeasterly
from the Azores covering the route flown by Flight 1-10. This high-pressure area
resulted in a western flow of relatively warm moist maritime air over the land
area in the vicinity of Shannon. A weak warm front was represented on the same
chart, extending from Iceland southeasterly through Eire. No adverse weather was
associated with this front in Eire, and at the time of the flight it had become
practically stationary. At
the time of take-off from London good flying conditions existed over the entire
route. Strato-cumulus clouds with bases at approximately 4,300 feet were formed
over the London area. At this time Shannon was reporting: "ceiling and
visibility unlimited, and wind front 270 degrees at 3 miles per hour."
Forecasts available to the flight prior to its departure indicated that
generally clear weather would be encountered for approximately the first two
thirds of the trip, then layers of broken clouds. These same forecasts indicated
that at the time of the flight’s arrival, Shannon would be covered by a layer of
broken stratus clouds at approximately 700 feet, and that visibility would be 4
miles. Prestwick, Scotland, the alternate, was predicted to have ceilings at
1,200 feet, visibility of 15 miles, and occasional light rain. A new terminal
forecast for the Shannon Airport received in London, at 2222, predicted that the
cloud base would become as low as 300 feet during the night hours of April 14,
1948. This new forecast was not received by the flight in London, but was
delivered to Pan American Airways at Shannon. Conditions
actually encountered by the flight en route were substantially the same as those
forecasted except that ceiling and visibility were considerably lower than had
been indicated to the flight by the forecast furnished at London. When the
flight approached the Shannon Airport, fog patches had formed, visibility was
reduced to 3 miles, and there were layers of broken clouds, with a ceiling of
400 feet. The wind was from 325 degrees at 4 miles per hour. At
0228, one minute after Flight 1-10 had reported making its 180 degree procedure
turn for its second approach to the Shannon Airport, visibility was reported as
reduced to 2 1/2 miles, and a layer of broken clouds was reported with a ceiling
of 400 feet with scattered clouds below at 300 feet. Fog patches were also
reported; however, as mentioned above, another flight that departed from Shannon
at approximately this time reported the ceiling northwest of the field to be 500
feet. Discussion
The
possibility of a defect in the operation of the instrument landing system at the
Shannon Airport was thoroughly investigated, since a distortion of the glide
path might contribute to an aircraft making an approach too low to clear the
ground. The instrument landing system was found to be operating normally when
flight checked. Furthermore, no deviation had been observed on the instrument
landing system monitoring board immediately before the landing approaches made
by Flight 1-10, and the monitoring system was found to give a true indication of
any material deviation of the glide path. Other components of the instrument
landing system, the localizer, the outer, middle, and inner markers, and the
compass locators, were all found to operate normally when examined and
flight-checked after the accident. Therefore, the possibility that the airplane
struck the ground as a result of maloperation of the ground installation for the
instrument landing system also seems to be extremely remote. An
erroneous reading of an altimeters of the instrument landing system indicator (ILS), or of any of the flight instruments could have misled the pilot during
his execution of the second approach. This possibility cannot be totally
eliminated, since the flight instruments were destroyed by fire; however, an
instrument approach is not made by reference to any one instrument. Furthermore,
one purpose in specifying a minimum approach altitude is to provide for a margin
of safety to compensate for possible errors in flight instruments. In view of
the fact that this flight executed one practice approach without reporting
difficulty, it appears very unlikely that any substantial maloperation of the
flight instruments existed. Certainly there was adequate opportunity for cross
reference and comparison of the readings of all the flight instruments before
initiating the second approach. It
was impossible at the scene of the accident to determine who occupied the
pilot’s seat. It may have been the first officer who had just previously to this
flight unsuccessfully flown a standard radio range approach into the Shannon
Airport. Nevertheless, the captain was responsible for the safe operation of the
aircraft, and it is to be presumed that he would have fulfilled his duty by
assuming control of the airplane, though he may have been in the co-pilot’s
seat, had he become aware of any hazardous condition of flight. The
only explanation of this accident that appears reasonable, considering all known
circumstances, is that the aircraft was flown too low in the approach for
landing. It is apparent that the airplane would not have struck the ground short
of the runway had the flight been able to establish clear visual reference to
the field, or had the flight not descended below the minimum approach altitude
of 415 feet in the execution of its second instrument approach. Accordingly, it
must be concluded that the airplane was flown below the minimum approach
altitude when no clear visual reference to the field existed. No
reliable evidence was obtained during the course of the investigation to
conclusively determine ceiling and visibility conditions over the approach area
to runway 23. The weather conditions that existed in the vicinity at that time,
however, were conducive to the formation of fog and low stratus clouds; and it
is highly probable that low layers of stratus clouds were formed very near the
ground between the outer marker and the end of runway 23. In view of the fact
that the surviving passenger stated that he was able to see the airport lights
when the airplane first passed over the airports at which time it was at an
estimated altitude of 500 feet, and that the ceiling was reported northwest of
the field to be 500 feet by another flight, ceiling and visibility conditions
over and to the west of the airport may have been considerably better than they
were over the area northeast of the field from which the landing approaches were
made. Therefore, the pilot in his execution of the second approach may have felt
confident that he would establish clear visual reference to the field in ample
time to safely execute a landing, and so continued below the minimum approach
altitude while still in instrument weather. Had
the aircraft been flown on instruments below the minimum approach altitude, and
had the pilot’s fluorescent fights then failed, the captain would have been in
the highly critical situation of being close to the ground without any means of
flight orientation. On the other hand, had the fluorescent lights failed prior
to the time that the flight reached its minimum approach altitude, there should
have been sufficient time and altitude to allow the captain and co-pilot to
accommodate themselves to the emergency. If
the pilot had had unobstructed visual reference to the runway, failure of the
fluorescent light on his side of the cockpit would not in itself account for any
particular difficulty in his completion of the landing approach. Airspeeds and
altitudes could have been called out by the co-pilot. If there had been a
failure of the pilot’s fluorescent fight before Captain Jakel established visual
reference to the runway when at or above the minimum approach altitude of 415
feet, there should have been sufficient time and altitude to place a flashlight
into use, or to focus the overhead chart fight on the pilot’s instrument panel.
In fact, he could have adjusted himself to watching the instruments on the right
instead of the left side of the instrument panel. However, had the pilot’s
fluorescent light failed when there was no or only intermittent visual reference
to the runway, and had the aircraft been flown close to the ground without clear
visual reference, the pilot might have been left without immediate means of
flight orientation at a time when a small loss of altitude would result in a
crash. Therefore, a failure of the fluorescent light might have contributed to
this accident, but could not be, in itself, the cause. Findings
Probable
Cause BY
THE CIVIL AERONAUTICS BOARD: Supplemental
Data Investigation
and Hearing Air
Carrier Flight
Personnel The
Aircraft The
No. 1 engine had a total of 2,491 hours, and 666 since the time of overhaul. The
No. 2 engine had a total of 1,789 hours, and 247 since overhaul. The No. 3
engine had a total of 2,149 hours and 667 since overhaul. The No. 4 engine had a
total of 2,627 hours, and 643 since last overhaul. The
aircraft was equipped with Hamilton Standard propellers, Model 33E-60-79. Copyright 1997, CASE All Rights Reserved. Embry-Riddle
Aeronautical University |
2001 PanAmAir.org ? Email PanAmAir.org |