Ice From a Clear Sky: Airliner 'Blue Ice' and Spain's Ice-Block Scare of January 2000

The first explanation to check when ice falls from the sky is the aircraft. In January 2000, Spain checked it, and its scientists still couldn’t find one.

The baseline: “blue ice”

On 3 September 1998, the Federal Aviation Administration published a proposed airworthiness directive for the Lockheed L-1011 airliner (63 FR 46927). The text sets out the problem plainly:

• The FAA had received “numerous reports” of leaks from airliner lavatory service systems freezing on the fuselage into “blue ice”, named for the blue toilet chemical.
• When that ice broke off and went into an engine, it had caused lost fan blades, severe engine damage and in-flight shutdowns. In two cases, the loads pulled the engine right off the airplane.
• There had also been “numerous reports” of blue ice falling from airplanes and striking houses, cars, buildings and other occupied areas on the ground. The FAA said it had no reports of anyone being hit, but judged the risk serious enough to act on, since more people were living near airports and most ice drops off during descent.

The fix was mechanical: replace seals regularly, run leak tests and put locking caps on the flush/fill lines. Blue ice is the ledger’s baseline for ice falls. It is real, documented, and a likely answer under a flight path.

Spain, January 2000

On 18 January 2000, El País reported that at least 15 large blocks of ice, some weighing about 3 kg, had crashed down across Spain in under ten days. Four new cases were reported the day before, in Valencia, Castellón and Zaragoza. Around midday that day, a block the size of a basketball smashed onto a local road between Sueca and Albalat de la Ribera under a completely clear sky, half a meter from a car with two people in it.

The usual explanations didn’t hold up:

• Not hail. A spokesman for the national meteorological institute said the falls couldn’t be ordinary hail or a hailstorm, because there was no cloud at the times and places they hit.
• Aircraft doubted. AENA, the airports and air-navigation authority, also discounted ice from planes and pointed out that some places, such as Soria and Cádiz, were far from any air route.
• A comet, as a long shot. CSIC geologist Jesús Martínez-Frías collected samples in a portable cooler packed with dry ice. His first read was “almost 100% frozen water.” He floated a disintegrating comet as a “remote” possibility, and ruled out meteorites, which are rock and metal.

Three days later the CSIC-coordinated team reported preliminary results, carried by the Servimedia agency in El Mundo:

• The team had narrowed its work to five falls it considered most “real”: Tocina (Seville), Chilches (Castellón), and Alcudia, Enguera and Algemesí (Valencia). They believed most of the cases reported in the preceding hours were fakes.
• The blocks were compact, strong and made of natural water with variable mineral content. Their chemistry differed from one block to the next, which the team read as forming at different times and temperatures. Silica and ammonium were present in all of them, but the scientists said nothing pointed to an extraterrestrial origin.
• They were convinced the ice wasn’t aircraft wastewater, and called ice condensed on a fuselage, or “minicomets,” possible but unlikely.
• Their preliminary hypothesis was an unusual atmospheric process high up, probably in the stratosphere, involving sudden cooling. CSIC vice-president Miguel García Guerrero stressed that other options weren’t ruled out.

What the ledger can say

• Blue ice: explained. The FAA documents it as a real hazard with a known mechanical cause.
• Spain 2000: open. The early reports are well sourced, and so are the official rule-outs of hail and the CSIC team’s rejection of lavatory ice. The stratospheric idea was a preliminary hypothesis. The ledger hasn’t read the CSIC team’s later isotope paper (the CSIC repository wasn’t reachable), so it won’t say whether that work settled anything.
• Copycats are part of the story. Within days, the scientists were treating most new reports as fakes. That’s one more reason to see each fall in this series in terms of who picked it up, when, and how it was kept.

If something falls near you, don’t handle or keep it. Report it to local authorities. Part of the Things That Fell series.

Sources

• Federal Aviation Administration, “Airworthiness Directives; Lockheed Model L-1011-385 Series Airplanes,” notice of proposed rulemaking, Docket 98-NM-200-AD, Federal Register 63 FR 46927–46932, 3 Sep 1998 (FR Doc 98-23741) — govinfo.gov
• Xavier Espanya, “Quince grandes bloques de hielo de origen desconocido caen sobre España en 10 días,” El País, 18 Jan 2000 — elpais.com
• Servimedia, “El CSIC cree que un fenómeno meteorológico inusual originó los aerolitos,” El Mundo, 21 Jan 2000 (page shows a 22 Jan update) — elmundo.es
• Not yet read by the ledger: the CSIC team’s later isotope study, “Oxygen and Hydrogen Isotopic Signatures of Large Atmospheric Ice Conglomerations” — digital.csic.es