During the last week of June, ALMA experienced extraordinary weather conditions: heavy snowfall covered the Array Operation Site (AOS), and even some snow covered the Operation Support Facility (OSF). An event like this one, caused by a cold front that generated winds of up to 100 km/h, had not been seen on this scale for more than 10 years.

In response to this scenario, the emergency protocols established by the safety team were immediately activated, including the suspension of access to the site, the activation of the ‘survival mode’ of the antennas, and constant coordination with the teams on the ground. These measures were essential to prevent major incidents and ensure the well-being of the personnel.

As a result of this experience, ALMA is promoting a comprehensive review of the Chajnantor Working Group (CWG) protocols, reinforcing access restrictions, clarity in the responsibilities of each institution, and emergency preparedness. In addition, the importance of maintaining fluid, two-way communication and the proper use of personal protective equipment, especially in adverse conditions, is emphasized.

‘A strong and unified safety culture must be cultivated in all CWG institutions through regular training, joint exercises and shared briefings to build trust, consistency and mutual accountability,’ said Iván López, Health, Safety and Environment Manager.

In addition to the proper handling of the event, this situation represents an opportunity to reinforce good practices and recall fundamental recommendations for the safety of all those operating in the Chajnantor plateau:

Recommendations in case of adverse weather conditions

• Always use the appropriate equipment: thermal clothing for extreme weather, portable oxygen, and a communication radio.

• Respect road closures: Access to the AOS must remain blocked when indicated by the ALMA Security team. Access is only permitted with formal authorization from the Director.

• Do not underestimate the risks: weather conditions at high altitudes can change rapidly. Acting with caution and judgment is key.

• Avoid hasty decisions: group coordination must always consider the consequences for people’s Safety.

• Always communicate your location: inform Safety when arriving at and leaving the site, ideally maintaining regular radio contact.

• Comply with CWG protocols: know and apply established procedures, understanding the consequences of non-compliance.

• Strengthen preparedness: Participate in joint training sessions with other CWG teams in response to emergencies.

ALMA will continue to work on reviewing and improving safety protocols together with the institutions that form part of the Chajnantor Working Group (CWG), to protect both the people and the scientific operations. We appreciate the commitment of each collaborator and reinforce the call to continue complying with established protocols, aligned with our values of Care and Collaboration, to protect the people, the environment, and to ensure the safe development of science.