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UK – EU Transition, and UK Civil Aviation Regulations

To access current UK civil aviation regulations, including AMC and GM, CAA regulatory documents, please use this link to UK Regulation. Please note, if you use information and guidance under the Headings, the references to EU regulations or EU websites in our guidance will not be an accurate information or description of your obligations under UK law. These pages are undergoing reviews and updates.

Ice falls – aviation and atmospheric

It is usually assumed that ice falling from the sky is aviation related, however ice falling from aircraft is relatively rare. In comparison to the 2.5 million flights a year in UK airspace during 2017, just seven icefall events were reported to the CAA. Going back to 2013, there were 25 reported events in that year, followed by 12 in both 2014 and 2015, and 10 in 2016.

Some ice falls may occur because ice which has naturally formed on an aircraft at higher altitudes breaks off as it descends into warmer air.

We have also received reports of discoloured ice which may carry an odour. This could originate from a leak from a faulty seal on a lavatory hose socket at a servicing point on an aircraft, which is used to unload waste liquid when on the ground. This is sometimes referred to as 'blue ice'. It should be noted that all lavatory waste is held within the aircraft and collected after landing by special vehicles during the preparation for the next flight. If the ice is clear, it may have been due to a leak from the potable water system at an external servicing point. This system provides clean water to an aircraft’s galley and lavatory system. A lot of assumptions can be made, but unfortunately it is impossible to trace a piece of fallen ice to a specific aircraft, if indeed that was its origin.


Fallen ice which is clear and uncontaminated may not have originated from aviation activity and there have been reports of falling chunks of ice which date back to before the existence of aircraft. There is current ongoing research into the phenomena by scientists across the world, which can be found via an internet search.

One example is Spain, where research began in January 2000 after unexplained chunks of ice weighing several kilogrammes fell over the country over a period of time. The event was unusual in that the skies were reported as cloudless during that time. A working group was set up by a planetary geologist in Madrid who was collecting and researching extreme atmospheric events. The intention was to analyse fallen ice to establish its composition.

The CAA’s role

EU Regulation requires UK operators to perform regular scheduled maintenance on their aircraft – from daily and weekly checks to more in-depth maintenance inputs at certain flight hours and cycles, dependant on the aircraft type and the manufacturer’s requirements. This action should contribute to minimising the risk of ice falls, as certain inspections will include attention to an aircraft’s external servicing points, therefore allowing the operator to take prompt corrective action if a defect is found.

As the safety regulator for UK civil aviation, the CAA oversees UK operators to check that they are following these requirements. The CAA is not responsible for the oversight of foreign aircraft which arrive and depart from our airports, however, inspections of foreign registered aircraft are undertaken on behalf of the Department for Transport, in accordance with their requirements.

Reporting an ice fall

We record reports of this nature as part of the CAA's Mandatory Occurrence Reporting (MOR) system. The reporting of safety occurrences helps us with the identification of safety hazards and the support of focused and proportionate safety actions.

You can submit a report using the following link (clicking the United Kingdom flag):


While we will record the details of your report, we are unable to investigate the potential origin of an ice fall and will not routinely provide feedback to you.

The CAA has no liability for damage which may be caused by an ice fall. Some airports operate voluntary schemes under which they will repair any damage, so it may be worthwhile contacting your local airport. Otherwise you should contact your insurance company in relation to any claim.

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