Icefalls – Aviation and Atmospheric

It is usually assumed that large pieces of ice falling from the sky are aviation related. Indeed the majority of reported icefall occurrences come from people living under or near the approach paths to major airports. Icefalls from aircraft are however relatively rare. In comparison to the 2 million flights a year  in UK airspace, which is about 5,200 flights a day, only around 25 icefalls are reported a year. Some of these instances may occur because ice, which has naturally formed on the fuselage in higher altitudes, breaks off as the aircraft descends into warmer air. 

Occasionally, there are reports of discoloured ice which may carry an odour. This could originate from a leak from a faulty seal on a hose socket which is used to load/unload liquid from the aircraft when on the ground. It should be noted that all toilet waste is held within the aircraft and collected after landing by special vehicles during the preparation for the next flight.

Megacryometeors

Ice which is clear and uncontaminated should not be assumed to have originated from aviation activity. Indeed there have been many reports of falling chunks of ice which date back to before the existence of aircraft. Research into the phenomena is ongoing by scientists all over the world but has so far been inconclusive.

Research into large falling ice began in January 2000 in Spain where unexplained chunks of ice weighing several kgs fell over the country during a 10 day period. 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 collect and analyse fallen ice to establish its composition. From the start of this research there have been many reports collated, including some from the UK.

The CAA’s role

As the safety regulator for UK civil aviation, the CAA requires UK aircraft operators to minimise the risk of icefalls by performing regular maintenance to prevent leaks and take prompt corrective action if a defect is found.

The CAA has an obligation to record reports of icefalls. These reports are entered onto the CAA's Mandatory Occurrence Reporting system, which is the UK's national database for aviation safety incident records. Such reports should be directed to the Information Management Department, (see below). This database contains aviation occurrence information which can be studied and analysed to assess safety implications and trends, and where possible initiate measures to reduce risks and enhance flight safety.

The CAA may investigate an icefall dependent upon individual circumstances, particularly the likelihood of establishing where the ice originated.

The CAA has no liability for damage which may be caused to property as a result of an icefall, and a reporter should initially contact their insurance company in relation to any claim.

The CAA does not have the facility to collect, analyse or store any ice.

Although the UK CAA is not responsible for the oversight of foreign aircraft which arrive and depart from our airports daily, inspections of foreign registered aircraft are undertaken on behalf of the Department for Transport. Further information can be found at the following links;

Aircraft Surveys

Safety Assessment Of Foreign Aircraft (EC SAFA Programme)

Reporting an icefall:

In the first instance, Email infoservices@caa.co.uk providing as much detail as possible about the event. Such details must include the time, location, damage to property, injuries to persons, and a description of the ice (including its approximate mass, colour and any odour). The reporter's name and telephone number should also be included. Associated photographs can be emailed as attachments.

Out of office hours

Duty Officer, CAA Corporate Communications Department           020 7379 7311

Will the CAA Investigate?

Due to the high numbers of aircraft arriving and departing from UK airports, combined with the high numbers of foreign aircraft overflying the UK at higher altitudes, it is extremely rare to be able to identify an aircraft that can conclusively be shown to be the source of an icefall.  As stated above, some icefalls may not be due to aircraft and some may be due to naturally occurring ice which is beyond the control of the aircraft operator. For these reasons few icefall reports will be investigated.

If investigated, possible sources may be initially identified through researching radar reports over the location at the time of the event. Factors including; aircraft speeds and altitudes, together with varying wind speed and direction, are taken into account as all of these combined elements affect the possible trajectory of a falling object.

Once potential sources of the ice have been identified the CAA will write to the operators of the aircraft, regardless of their nationality, to request examination of the aircraft’s technical records for any possible causes. This process can take some time to complete and does not usually result in identifying the cause. In every case prior to 2012, where a fault had been identified, corrective action had already been implemented by the Airline.