Western Air Express flight 7
| Western Air Express flight 7 | |
|---|---|
 Identical aircraft from another company |
|
| Accident summary | |
| Accident type | Controlled flight into terrain |
| place | Los Pinetos, San Gabriel Mountains |
| date | January 12, 1937 |
| Fatalities | 5 |
| Survivors | 8th |
| Injured | 8th |
| Aircraft | |
| Aircraft type | Boeing 247-D |
| operator | Western Air Express |
| Mark | NC-13315 |
| Departure airport |
Las Vegas Municipal Airport , United States
|
| Destination airport |
Union Air Terminal , Burbank , United States
|
| Passengers | 10 |
| crew | 3 |
| Lists of aviation accidents | |
On January 12, 1937, a Boeing 247 on Western Air Express Flight 7 approached Burbank from the planned flight path and flew into a mountain in the San Gabriel Mountains in poor visibility . Five occupants were killed in the accident; the remaining eight people on board were injured, some seriously. Documentary filmmaker Osa Johnson was one of the injured . Her husband Martin Johnson succumbed to a traumatic brain injury the day after the accident .
Flight history
The Boeing 247 ( license plate : NC-13315) of the Western Air Express was on a scheduled flight from Salt Lake City ( Utah ) about Las Vegas ( Nevada ) and Burbank to San Diego (both California ). The plane landed in Las Vegas at 8:27 am local time and was scheduled to fly to Burbank ten minutes later. The departure from Las Vegas was delayed because no current information was available about the weather conditions at the destination airport. The crew received a clearance to the Daggett radio beacon in San Bernardino County at 9:00 a.m. with the instruction that if the weather in Burbank deteriorated, they would move to Palmdale or Long Beach . While the machine was flying west, air traffic control gave permission to continue flying to Burbank via the undirected radio beacons in Palmdale and Saugus .
Halfway between Palmdale and Saugus, the crew lost sight of the ground at cruising altitude of 2130 meters (7000 feet ) and switched to instrument flight . At 10:50 the machine reached the silence cone of the Saugus radio beacon and turned right on a northwest course. This change of course, by which the aircraft initially moved away from the destination airport, corresponded to the standard approach procedure for Burbank and served to reduce altitude. The pilots extended the landing gear , reduced the airspeed to about 220 km / h (120 kts ) and began the prescribed descent to 1675 meters (5500 feet). After the aircraft sank to this altitude, it encountered severe turbulence that made it difficult for the crew to navigate and maintain an exact altitude. In addition, the captain informed the company headquarters in Burbank about the formation of ice on the aircraft. Three minutes after starting the northwest course, the pilots initiated a 180-degree turn and then flew over the Saugus radio beacon again. Due to the turbulence, this overflight was 90 meters (300 feet) too deep.
After flying over the Saugus radio beacon for the second time, the crew deviated from the established approach route. By default, the machine should have flown south for two minutes, dropping to 1,370 meters (4,500 feet). The navigation should then be aligned with the four-course beacon in Burbank. The pilots continued to descend as instructed, but did not turn to a southerly course. Instead, they continued in a southeasterly direction and came over the San Gabriel Mountains . At 11:05 a.m., the master reported that he had received the N-tone which the four-course beacon in Burbank was sending as Morse code to the eastern area . He correctly concluded from this that the aircraft was away from the usual approach route at a low altitude over mountainous terrain. According to a statement by the captain, who survived the accident, he initiated a left turn to the north in order to avoid lower terrain. In the course of this curve, the machine grazed the western flank of the Los Pinetos mountain with its left wing tip at an altitude of about 1080 meters MSL (3550 feet) . The aircraft then hit a left bank angle, skidded around the summit and came to a halt after just under 40 meters (125 feet) on the south side of the mountain. The hull remained largely intact.
Cause of accident
The frequency of the four-course beacon in Burbank was used both for flight navigation and at times for regular radio communications. As long as the air traffic controller spoke to the arriving and departing crews, this frequency was not available for navigation purposes. The pilots were aware of the dual use.
For an unexplained reason, the crew aligned their navigation directly after the second overflight from Saugus to the radio beacon in Burbank and did not initially turn south as prescribed. After setting their receivers accordingly, the pilots noticed that the air traffic controller in Burbank was currently talking to other aircraft on this frequency. Assuming that the talks would soon be over, the master maintained the south-easterly course and the descent. Nor did he switch back to the frequency of the Saugus radio beacon. Over the next four minutes, the aircraft continued to deviate from the specified flight path without any response from the crew. The master contacted the air traffic controller at 11:01 a.m. and asked him to stop all radio communications for navigation purposes. The pilots then received the N-tone (not the expected A-tone broadcast in a westerly direction) from the four-course beacon Burbank and reported this to the air traffic controller at 11:05. Based on the N-tone, the crew recognized that they were at an unknown position east of the airport, presumably over the San Gabriel Mountains.
The exact flight path from Saugus to the scene of the accident remained unclear, as did the exact time of the accident, which was estimated at 11:07 a.m. Taking into account the speed, the machine would have had to cover a distance of around 32 kilometers (17.5 NM ) in the ten minutes between the second overflight of the Saugus radio beacon and the occurrence of the accident . In fact, the plane hit just ten kilometers (5.5 NM) southeast of Saugus. Because of this discrepancy, the investigators assumed that the crew must have flown at least one full circle over the San Gabriel Mountains, unlike the captain's description. It remains unclear why the pilots did not go into the climb. A possible wing freezing was ruled out as a cause.
consequences
Osa Johnson sued Western Air Express and airport operator United Airports of California for the death of her husband for a total of $ 502,539 in damages. The lawsuit was dismissed by a Los Angeles district court in the summer of 1941.
Individual evidence
- ^ A b c d e f Department of Commerce, Washington DC: Report of the Accident Board , official final report, accessed February 13, 2017
- ↑ Los Angeles Times Archive: Osa Johnson Loses Appeal, July 1, 1941 , accessed February 13, 2017
Coordinates: 34 ° 21 ′ 15 " N , 118 ° 27 ′ 33" W.