History of the Swiss Air Disaster

The Swiss Air Disaster, April 10th 1973

Fifty years on and the depth of emotion is still apparent in the Somerset communities devastated by an air crash in Switzerland. On April 10 1973 nearly 140 people, mainly mothers, boarded Invicta Airlines Flight 435 at Bristol Airport happily looking forward to a day’s trip to Basle. A total of 108 people were killed when the plane struck the tops of trees and crashed into a hillside on its second attempt to land at the Swiss airport during a snowstorm.

Invicta International Airlines Flight 435 (IM435) was a Vickers Vanguard 952, with the call sign Oscar Papa, flying from Bristol Lulsgate to Basel-Mulhouse, which crashed into a forested hillside near Hochwald, Switzerland on 10 April 1973. The aircraft somersaulted and broke up, killing 108 people, with 37 survivors. To date, this is the deadliest accident involving a Vickers Vanguard and the deadliest aviation accident to occur on Swiss soil.

Oscar Papa at Manchester Airport

The aircraft, registered as G-AXOP, and was chartered by a tour company based in Britain. Flight 435 took off from Bristol Lulsgate Airport for EuroAirport Basel Mulhouse Freiburg International Airport in Basel, Saint-Louis, France. The airport was located just miles from the border of Switzerland and Germany. Early on the day of the crash, the aircraft departed from London‘s Luton International Airport and made a short positioning flight to Bristol where 139 passengers boarded.

At 07:19 UTC, Flight 435 took off from Bristol. Captain Anthony Dorman flew the plane, while his co-pilot Captain Ivor Terry was handling communication. The flight was uneventful until its first approach. It was daylight at the time, so visual references could be easily obtained by the crew. However, a heavy snowstorm was reported in Basel, thus reducing the visibility there.

While approaching Basel, Flight 435 passed two approach beacons, named as beacon MN and BN, the latter of which was the outer marker of the Instrument Landing System at the airport. However, the aircraft overshot. Captain Dorman then initiated a go-around.

At 09:08 UTC, while Flight 435 was manoeuvring for its second approach, Basel Control Tower received a telephone call from a meteorologist and a former aircraft commander reporting that barely two minutes previously, Flight 435 had flown above the Binningen Observatory (approximately eight kilometers southeast of the airport) at a height of around fifty meters while heading south; he urged the crews of Flight 435 to climb immediately. During the approach, several passengers briefly saw several houses on the ground. While the meteorologist was still on the phone, the crew reported that they had passed the first beacon, named as MN. They were instructed to pass the second beacon, BN. In reality, when the crew reported over MN, they were actually in the vicinity of a third beacon, BS, and had already overflown the airport, heading south.

At 09:11 UTC, Zurich Area Control Centre asked Basel Control whether they had an aircraft which was flying outbound from the airport towards Hochwald, as they had observed an unidentified echo on their radar screen, a few miles south of Basel. Basel Control Tower denied this, but when the controller checked his radar screen he saw an unidentified echo moving to the south, a few miles from the airport. Notwithstanding this, Flight 435, having reported that it had passed beacon BN, was given a landing clearance.[5]

After finishing his telephone call with Zurich, the Basel controller asked if Flight 435 was sure that they had passed beacon BN. Flight 435 replied that they had a “spurious indication” and that they were joining the localiser, an electronic signal marking the extended centre-line of the runway. The crew then confirmed that they were established on the glide path and localiser, while the controller stated that he could not see them on his radar screen. The controller then informed the crew: “I think you are not on the…you are on the south of the airfield.” Flight 435 didn’t respond. After this message, all calls to Flight 435 went unanswered.

At 09:13 UTC, the aircraft brushed the wooded area of a range of hills in Jura and crashed in the hamlet of Herrenmatt, in the parish of Hochwald, some ten miles (16 km) south of the airport and while flying away from it. The aircraft somersaulted and exploded, several parts of it catching fire. 108 passengers and crew were killed, while 37 others survived the crash; 36 of these were injured, one air crew was unhurt.

On hitting the ground, the aircraft snapped into several sections. While the front parts were “destroyed into bits”, a section of the tail was left substantially intact. This was the area where most survivors were found. Everyone seated in the front part of the aircraft had been killed.

This video shows the scene of the crash site, you may not want to watch this.

In the aftermath of the crash, survivors began helping each other. It was snowing at the time, and hypothermia could easily occur. While pulling bodies from the wreckage, they began chanting hymns to keep their spirits high. Shortly afterwards, a boy from a nearby farm found the survivors, and led them to his house, where his family sheltered and took care of them while waiting for rescue services to arrive.

Malcolm Smith, the Bristol Post reporter who travelled to the site, reported from the village of Herrenmatt, Dornach, near Basle:

A boy of 14 from Somerset stood on the steps of the old school house here this afternoon and wept unashamedly, comforted by a woman officer of the Salvation Army. ‘Inside the building he had just witnessed the most sobering of all moments – seeing laid in rows the dark-stained coffins of the victims of the Vanguard crash.
It was the moment when my courage failed. I could not ask his name. This was his moment to be alone and the emotion swept through the small gathering of onlookers and the grey uniformed police who cast their gaze away from the pitiful scene. This is the darkest hour for the relatives and friends who faced the awful task of identifying their loved ones. It was harrowing to them all and they faced the challenge nobly.
There was the impassive husband clutching a polythene bag with a coat and a handbag inside. There was the family group distressed but calm in the face of failure to find any clue which pointed to what happened to their daughter, an 18-year-old with a love of flying.
Dornach this afternoon is bathed in sunshine. On the mountainside, still snow – covered a few miles away, lies the wreckage of Oscar Papa.

Malcolm Smith, Bristol Post

To date, this is deadliest aviation accident to occur in Switzerland. Many of the 139 passengers on the charter flight were women from the Congresbury, Axbridge, Cheddar, Winscombe, Yatton, Wells, Wrington, Redhill, Claverham, the surrounding villages and across Bristol . The accident left 55 children motherless and became known in the British media as the Swiss Air Disaster.

The investigators of the crash in their final report recommended that Basel Airport provide radar guidance to inbound aircraft; that the radio beacons in the Basel area emit modulated signals as required by ICAO; that unpublished ILS back beams be suppressed; that approach charts contain information to help pilots cross-check their location relative to nearby radio navigational aids; and that all aircraft over a certain size be equipped with a ground proximity warning system.

Today, all of these improvements have been implemented, mostly in response to a series of crashes rather than due to the accident of Oscar Papa. That such an accident could not happen today, provides little comfort to the families of the victims 50 years later, who still grapple with the simultaneous loss of so many members of their families.

The video below shows a compilation of the news coverage from 1973 up to to the 40th Anniversary in 1993.