Extreme weather events brought air traffic in eastern Austria to a virtual standstill overnight into Tuesday. Freezing rain created a thick layer of ice on the runways and taxiways of Vienna-Schwechat Airport, making safe flight operations impossible. For safety reasons, the airport operator had to temporarily suspend all operations during the morning hours. The closure led to significant logistical challenges throughout the region.
Numerous long-haul flights and European feeder flights were unable to reach their destinations and had to be diverted to alternative airports in Germany, Italy, and southern Austria. Graz Airport was particularly affected, serving as the primary diversion airport due to its geographical location and technical infrastructure, and consequently experiencing an exceptional increase in wide-body aircraft. It wasn't until around midday that winter maintenance crews in Vienna were able to prepare the runways sufficiently for operations to gradually resume, although delays and subsequent disruptions plagued the entire day.
Challenging logistics at the Graz alternative airport
While winter maintenance crews at Vienna Airport had been working non-stop since the early hours of the morning to combat the thick layer of ice with heavy equipment and de-icing agents, Graz Airport was a hive of activity. A total of seven aircraft originally scheduled for Vienna landed on the Graz runway. Among them were aircraft types rarely seen in Graz's regular flight schedule. Particularly noteworthy were an Austrian Airlines Boeing 767 from Washington and a Boeing 787 Dreamliner from Bangkok. Aircraft from Dubai, Barcelona, Athens, Sharjah, and Bristol also diverted to Graz.
The sudden arrival of hundreds of passengers required swift decisions from the respective airlines and airport authorities. Wolfgang Grimus, Managing Director of Graz Airport, and spokesperson Doris Pölt explained the airlines' different approaches. While Austrian Airlines passengers disembarked and were transported to Vienna by hastily organized buses, the Taiwanese airline EVA Air decided to keep its passengers on board. Around 300 passengers had to wait several hours on the aircraft until Vienna Airport gave the go-ahead and the planes could finally take off for the last short leg of their journey.
Meteorological causes for the traffic chaos
The phenomenon of black ice that paralyzed Vienna Airport is caused by a specific weather pattern. Meteorologists describe the process as freezing rain, in which mild air masses at mid-altitudes of 1.000 to 2.000 meters glide over a layer of cold air near the ground. The precipitation melts in the warmer layer and becomes rain, which then freezes within fractions of a second upon contact with the frozen ground. This process creates a mirror-smooth surface that often renders conventional de-icing agents ineffective and necessitates specialized chemical de-icing agents.
Although Graz was spared the extreme black ice formation, airport management emphasizes that they are prepared for such scenarios. Staff are on constant standby when corresponding weather forecasts indicate the need to clear runways and de-ice aircraft before takeoff. Air traffic safety is the top priority, which is why closures like those in Vienna are considered an unavoidable preventative measure as soon as traction for the landing gear can no longer be guaranteed.
Impact on rail transport and the Austrian Federal Railways (ÖBB)
Not only air traffic was affected by the weather, but rail traffic also struggled with the effects of the icing. The Austrian Federal Railways (ÖBB) were forced to maintain a travel warning for Vienna, Lower Austria, Upper Austria, and Salzburg. While the railway lines in Styria remained largely ice-free, disruptions in the northern federal states led to massive delays across the entire network.
Connections from Linz or Salzburg to Graz were particularly affected by delays, as icy overhead lines and points failures at key junctions disrupted service. The ÖBB app also reported temporary train cancellations between Vienna and Graz. The national railway company asked passengers to postpone non-essential journeys. The situation on the tracks only gradually eased with the onset of a thaw on Tuesday afternoon.
Return to normal operations and postoperative care
After flight operations resumed at Vienna Airport around 11:00 AM, it took several more hours for flight schedules to stabilize. Aircraft that had made stopovers in Graz and other cities had to be gradually integrated into the regular traffic flow. Because many crews reached or exceeded their legally mandated duty hours due to the diversions, this led to additional staff shortages and further delays for subsequent flights.
The operators of Vienna and Graz airports have drawn a mixed conclusion from the events. On the one hand, the swift closure and professional handling of the diversions prevented any danger to passengers and equipment. On the other hand, the incident highlights the sensitivity of modern transport infrastructure to sudden weather changes. Cooperation between the airports functioned seamlessly, which is seen as evidence of the effectiveness of the regional emergency plans. The situation remains tense for the coming days due to fluctuating temperatures, and the emergency teams at both locations remain on high alert.