The story of Swiss International Air Lines Flight 850

Summary

• SWISS Flight 850 experienced weather-related delays and a change of aircraft before departure.
• Due to the limited landing options, it was decided to land in Werneuchen.
• The lack of weather data contributed to a lengthy investigation.

In July 2002, a Saab 2000 (registered HB-IZY) of Swiss International Air Lines on Flight 850 was unable to land at its intended destination, Fuhlsbüttel Airport in Germany, due to bad weather. The pilots made several unsuccessful attempts at nearby airports before deciding to land at Werneuchen.

During landing, the plane hit an embankment and all three legs of the landing gear were torn off. The damaged turboprop plane eventually came to rest on its belly. Fortunately, only one passenger suffered minor injuries, but the plane had to be written off.

Weather errors and aircraft changes

On July 10, 2002, Swiss International Flight 850 was scheduled to depart from Basel, Switzerland for a relatively short flight to Fuhlsbüttel Airport in Hamburg, Germany. The aircraft selected for this route was an Embraer 145, but mechanical problems necessitated a change of aircraft. A Saab 2000 was selected as a replacement.

The flight’s departure time was delayed for two reasons: the aircraft change and some discussions about the forecast weather conditions near Hamburg at the estimated time of arrival (ETA). The crew decided to carry additional fuel in case an instrument hold was required.

The Meteorological Terminal Air Report (METAR) from Fuhlsbüttel indicated a thunderstorm front near the airport. The forecast wind speeds of up to 45 knots in Hamburg and the selected alternatives of Hanover and Bremen caught the pilots’ attention during the briefing. Unfortunately, the Significant Meteorological Information (SIGMET) reports issued from Basel about an hour before departure were not reviewed. These reports were not made available to the flight crew.

The SIGMETs showed that a front was forming in the region, likely to produce thunderstorms peaking at FL380 (38,000 feet, 12,000 meters) in the Bremen area. The Terminal Aerodrome Forecast (TAF) for Fuhlsbüttel Airport predicted steady winds of 20 knots with gusts up to 40 knots close to expected convective weather.

A bumpy ride

After a ten-minute departure delay, Flight 850 left the gate at 5:55 p.m. and took off for Hamburg at 6:09 p.m. with four crew members and 16 passengers. As expected, the pilots soon encountered turbulence and requested air traffic control vectors for cells of heavy precipitation en route.

At 19:36, the Saab 2000 began an ILS approach to runway 23 at Fuhlsbüttel. When the aircraft reached an altitude of 3,000 feet, it encountered severe turbulence associated with a thunderstorm cell that had formed over the airport. The crew initiated a go-around to request an instrument stop near the area.

The Saab’s fuel tanks were sufficient for a 45-minute stay. Although the weather in Bremen was better than in Hamburg (wind speed 9 knots with visibility of just over 6 kilometers), a diversion there was not a viable option because a convective weather line had formed between Hamburg and this alternate airport.

Landing options are restricted

At 19:49, air traffic control informed flight 850 that another aircraft could land on runway 33 in Hamburg, but the crew decided against attempting to land due to the still strong wind. Instead, the pilots decided to divert to Hanover and requested that the aircraft be left the holding pattern for this purpose.

At 20:18, Flight 850 took off for Tegel Airport in Berlin after receiving reports of clear skies and other favorable conditions from the airport’s Automatic Terminal Information Service (ATIS). The crew requested priority handling as they had 40 minutes of fuel left. Unfortunately, the frontal system that had prevented the flight to Bremen had now approached Berlin, and severe turbulence occurred again during the approach.

Once again, the crew requested an alternative airfield from air traffic control. The controller suggested landing at Eberswalde Finnow, just 27 nautical miles away. The crew readily accepted this, but once again the weather limited the crew’s options as thunderstorms swept over that airfield and massive cells made landing at other nearby options, including New Brandenburg, impossible.

Knowing that fuel shortages were a serious problem at this point, further communications between air traffic control and the pilots of Flight 850 eventually focused on landing at Werneuchen Airfield, 20 nautical miles away. In addition to ongoing weather threats, the airport presents its own challenges.

The good news was that there was a long runway that had previously been used by military aircraft. On the other hand, however, part of the landing area was unusable. An earthen embankment had been built on part of the runway to prevent illegal car racing on the airfield. Therefore, the usable runway length for Flight 850 was 4,900 feet (1,500 meters). As if that wasn’t challenging enough, the runway was unlit and had no optical aids, as it was currently only used for ultralight aircraft.

Touchdown (and unexpected deceleration) on the runway

At 20:40, radar controllers cleared Flight 850 to approach the airport without a control tower. The pilots were advised to land further down the runway due to the embankment.

Without runway lights or other visual aids, the first officer landed the Saab 2000 in front of the obstacle, causing all three landing gears to be torn off before the aircraft skidded about 350 meters down the runway. Fire warnings were sounded for engine No. 2 and the crew activated the fire suppression systems for both engines. Fortunately, there were no fatalities among the 20 people on board (16 passengers and 4 crew).

A thorough and lengthy investigation

The Federal Bureau of Aircraft Accident Investigation (BFU) conducted the accident investigation, which lasted over eight years. There was no explanation as to why the investigation process took so long, but the BFU’s findings were clear. The agency blamed the lack of available and accurate weather data as one of the reasons. In particular, the pilots’ pre-flight briefing did not benefit from the SIGMETs, which clearly indicated a deterioration in the forecast weather conditions in parts of Germany.

In addition, the faulty ATIS transmission at Berlin-Tegel Airport reported good weather, although the opposite was the case. The BFU systematically referred to insufficient information at Werneuchen Airport due to “an unclear map representation and misleading or missing communication” and “inadequate labeling/marking of the operational and non-operational areas of the airport.”

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• 

  SWISS

  IATA/ICAO code:

  LX/SWR

  Airline type:

  Full-service transport company

  Hub(s):

  airport Zurich

  Founding year:

  2002

  Alliance:

  Star Alliance

  Airline group:

  Lufthansa Group

  CEOs:

  Dieter Vranckx

  Country:

  Switzerland