Alaska Airlines Flight 1866
| Alaska Airlines Flight 1866 | |
|---|---|
 An identical machine from Alaska Airlines |
|
| Accident summary | |
| Accident type | Controlled flight into terrain |
| place | near Haines Borough , Alaska , United States
|
| date | 4th September 1971 |
| Fatalities | 111 |
| Survivors | 0 |
| Aircraft | |
| Aircraft type |
Boeing 727-193
|
| operator |
Alaska Airlines
|
| Mark |
N2969G
|
| Departure airport |
Ted Stevens Anchorage International Airport , Alaska , United States
|
| 1. Stopover |
Merle K. (Mudhole) Smith Airport , Cordova , Alaska , United States
|
| 2. Stopover |
Yakutat Airport , Alaska , United States
|
| 3. Stopover |
Juneau Airport , Alaska , United States
|
| 4. Stopover |
Sitka Airport , Alaska , United States
|
| Destination airport |
Seattle-Tacoma International Airport , Washington , United States
|
| Passengers | 104 |
| crew | 7th |
| Lists of aviation accidents | |
The Alaska Airlines flight 1866 (Flight number: AS66 , call sign: ALASKA 66 ) was a line domestic flight of the US airline Alaska Airlines . On this flight, a Boeing 727-193 collided with a mountain on September 4, 1971 near Haines Borough , Alaska , after the machine went off course due to unreliable navigation signals. All 111 people on board the machine were killed in the accident. Until another Boeing 727 crashed on Eastern Air Lines Flight 66, it was the most serious aircraft accident in the USA with only one machine involved.
machine
The aircraft involved in the accident was a Boeing 727-193, which was five years and two months old at the time of the accident. The machine was the work of Boeing on the Boeing Field in the state of Washington mounted. The aircraft had the serial number 19304 , it was the 287th Boeing 727 from ongoing production. The machine was approved by the manufacturer with the aircraft registration N2969G and completed its maiden flight on June 24, 1966. From November 1, 1967, the machine was delivered to Pacific Air Lines , which from November 1967 to November 1968 then to BWIA West Indies Airways from Trinidad and Tobago . In April 1968 the owner company of the machine was renamed Hughes Airwest , whereupon the Boeing was transferred to their fleet. From March 1969 to February 1970 the machine was leased to Braniff International Airways , where it was operated with a green livery. With Alaska Airlines the machine was in operation from September 1970. The three-beam narrow-body aircraft was with three Turbojettriebwerken type Pratt & Whitney JT8D-7B equipped. By the time of the accident, the machine had completed a total of 11,344 operating hours.
crew
There was a seven-person crew on board the machine, consisting of a pilot, a first officer, a second officer and four flight attendants. The captain on the flight was Richard C. Adams, aged 41. Adams had 13,870 hours of flying experience, including 2,688 hours on the Boeing 727. First Officer Leonard D. Beach, 32, had 5,000 hours of flying experience, 2,100 hours of which on the Boeing 727. The 30-year-old James J. Carson was the second mate and had completed 2,850 hours of flight time, about 2,600 hours of which with the Boeing 727. Beach and Carson were both hired by Alaska Airlines in 1966, and Adams had been with the airline since 1955.
Passengers and flight schedule
The flight connection connected the Ted Stevens Anchorage International Airport with the Seattle-Tacoma International Airport . After taking off from Anchorage, the first flight to Merle K. (Mudhole) Smith Airport in Cordova (Alaska) was . The second leg of the flight was to go to Yakutat Airport , from where the flight was to Juneau Airport . Before the plane was supposed to fly on to Seattle, there should be a final stop at Sitka Airport . The plane crashed at the end of the second leg of the flight, when approaching Juneau.
104 passengers had started the flight on the affected flight segment.
Flight history
The plane left Anchorage punctually at 9:13 a.m. local time. The first stopover at Cordova went without a hitch, apart from a small problem with a loading door, which led to a short delay. The plane left Cordova at 10:34 a.m. and landed in Yakutat at 11:07 a.m. The machine started at 11:35 a.m. for the next leg of the route to Juneau with 104 passengers and 7 crew members on board.
the accident
At 11:46 a.m., the crew contacted Anchorage air traffic control and reported that they were at an altitude of 23,000 feet, 104 kilometers east of Yakutat. The air traffic controller gave the pilots clearance to fly over the PLEASANT junction at an altitude of 10,000 feet and cleared an onward flight to the HOWARD junction. He gave the crew the barometric data for Juneau to adjust the altimeter and instructed them to report again when they reached an altitude of 11,000 feet.
At 11:51 a.m., the crew informed air traffic control that they were initiating a descent of 26,000 feet so that they would have reached an altitude of 10,000 feet by the PLEASANT junction.
At 11:54 a.m., the air traffic controller instructed the crew to stop the descent at an altitude of 12,000 feet for the time being and to remain at this altitude. He justified this with the fact that there was another machine in the airspace near Juneau. A Piper PA-23 Apache (N799Y) had taken off from Juneau Airport for a flight to Whitehorse at 11:44 a.m. and was located near the HOWARD hub. At 11:55 a.m., the crew of the Boeing 727 confirmed that they had reached the altitude of 12,000 feet and would be holding the altitude. The Piper's altitude was not known and there was disagreement about which route the machine should fly. In the case of several radio messages, the Boeing crew took on the role of an intermediary between air traffic control and the Piper.
At 11:58 a.m., the crew reported that they were flying over the PLEASANT junction and flying a holding pattern there. The controller gave the pilots clearance for the onward flight to the HOWARD hub. He asked them if they had the cloud cover below them at their 12,000 foot altitude, to which the pilots replied that they were flying through the cloud layer in instrument flight. At 12:00 noon the controller repeated the clearance for the HOWARD junction and informed the pilots that, as expected, they would have to fly holding patterns around this junction until 12:10 p.m. At 12:01 p.m. the crew confirmed that they would start flying the holding patterns.
At 12:07 p.m., the air traffic controller inquired about the current position of the aircraft within the holding pattern. The pilots replied that the machine was flying on the inbound leg and that they were using ILS and LOC to align it with the HOWARD node. The controller then gave the pilots clearance to approach runway 08 in instrument flight and instructed them to fly over the HOWARD junction at an altitude of 9,000 feet or less. The crew confirmed receipt of the radio message and announced that they were leaving their flight altitude of 12,000 feet. When the air traffic controller inquired about the aircraft's altitude a minute later, the crew informed him that it was just below 5,500 feet, whereby he immediately corrected this figure to 4,500 feet. The controller instructed the pilots to contact Juneau approach control. The crew then changed the radio frequency. The controller in Juneau gave them the weather report and told them which runways were available. He instructed the pilots to report as soon as they fly over the BARLOW junction.
Subsequently, no further radio messages were sent from the machine. At 12:15 p.m., the Boeing collided with the eastern slope of a canyon in the Chilkat Range in the Tongass National Forest at an altitude of 2,500 feet and 18.5 miles west of Juneau . The machine exploded on impact and all 111 people on board were killed.
When the controller in Juneau did not receive any replies to his radio messages to the aircraft, he notified the local authorities. A search operation was initiated immediately; the wreckage of the completely destroyed machine was found after a search lasting several hours.
Two witnesses who were near the Chilkat mountain range said they heard a low-flying, jet-powered aircraft but were able to access the machine due to clouds and poor visibility from a blizzard (they estimated visibility ranges from 200 to 300 feet). The witnesses described the engine noise as normal. A short time later they heard an explosion. A third witness in the area saw a low-flying plane disappear into the clouds, but heard no impact sound.
Accident investigation
The National Transportation Safety Board (NTSB) investigated the accident. The cockpit voice recorder (CVR) and the flight data recorder (FDR) were recovered from the crash site and read out. The wreck was inspected and some items were removed for further investigation by the NTSB and the manufacturers of the respective aircraft assemblies. After determining that there were no obvious problems with the training of the crew or the aircraft, their investigation focused on the navigational equipment and the approach technique performed. Both navigation receivers on the aircraft were in good condition and all ground navigation stations were also working properly. The evaluation of the recordings of the voice recorder showed that the crew had not used the acoustic identification functions of the radio navigation devices. In addition, they did not use all available navigational aids to determine their position, although the accident report noted that the approach procedure carried out did not necessarily require the use of these devices. The investigators also suspected that the coordination between the two pilots when coordinating the radio navigation equipment was inadequate. After comparing the conversations between the pilots with the incorrect position report over the BARLOW junction, the NTSB found that the master's radio navigation device had apparently consistently displayed incorrect parameters at several points along the approach route. No reason for the false reports could be determined. The NTSB also determined that air traffic control had applied the correct procedures to pilot the machine. The small aircraft entering the airspace during the descent may have distracted both the air traffic controller and the pilots.
The NTSB final report was published on October 11, 1972. The investigation produced the following findings:
- The machine had been properly certified, serviced and loaded, and there were no failures or malfunctions in the technical assemblies, engines or control systems.
- The crew has been certified and qualified for use.
- Air traffic control behavior was appropriate and complied with the prescribed procedures and standards.
- The false clearance for N799Y resulted in this aircraft entering the airspace, so its presence created an additional workload for air traffic control from both an air traffic control and communications perspective.
- The involvement of the Boeing crew in the actions of the crew of the N799Y and the uncertainty about the position and flight path of this aircraft may have distracted the Boeing crew.
- The crew did not use audio identification procedures when calibrating the navigation equipment.
- It could not be ascertained that there was an effective division of labor between the pilots when the first officer changed his VHF navigation frequency from the VOR to the instrument landing system and asked the master to stop the radio beacon.
- The crew was exposed to apparently correct, but incorrect, navigation information that led to a premature descent into impassable terrain.
- There was no malfunction of the altimeter.
- The indicated junctions along the approach route to Juneau were shifted about 35 to 40 degrees counterclockwise according to the calls recorded by the crew.
- The captain's radio receiver was tuned to the Juneau radio beacon at the time of impact. The associated rotary switch was only activated immediately before the impact.
- There was no evidence that the crew had used all available navigation facilities to check the flight progress along the locator.
- Flight tests and other investigations did not reveal any malfunction of the Sisters Island rotary radio beacon, which would have led to a significant misdirection on the day of the accident.
- Investigations and tests of the avionics assemblies of the recovered aircraft did not reveal any deviations from normal operation.
- Investigations into possible discrepancies between the Doppler rotating radio beacons and the navigation devices of the machine did not provide any information
The NTSB investigated whether it was possible that military installations intentionally disrupting radio traffic could have caused the faulty navigation displays. The investigations came to nothing, so that the thesis was rejected again.
The NTSB gave incorrect and misleading navigation displays as the most likely cause of the accident. This would have tempted the pilots to descend prematurely, in which the machine was flown below the minimum descent altitude, which was not apparent to the pilots due to the false indications. The cause of the false indications could not be determined. The investigative commission also found that not all facilities for determining the position of the machine had been used, but that the use of further navigation aids was also not required. Furthermore, the crew did not initiate any audio identification of the navigation devices concerned.
swell
- Aircraft Accident Report - Alaska Airlines, Inc., B-727, N2969G, near Juneau, Alaska, September 4, 1971 , National Transportation Safety Board , October 13, 1972.
- B-727-193 N2969G , Aviation Safety Network , accessed March 31, 2020.
- NTSB Identification: DCA72AZ003 , National Transportation Safety Board
- James Brooks: The disaster that taught us to fly safely: 45 years after Flight 1866 , Juneau Empire , September 3, 2016.
Coordinates: 58 ° 21 '42 " N , 135 ° 10' 12" W.