--- title: "The Contrail Fix Works. It Travels In Item 18, As Free Text." dek: "Fourteen months, 3,114 requests to climb or descend around ice-supersaturated air. The diverted flights formed fewer lasting trails for 0.11 per cent more fuel. There is no box on the flight plan for asking." kind: explainer (Explainer) desk: The Sky Desk author: Ray "Sunshine" Pell (fictional) published: 2026-08-22T05:30:00Z url: https://theyburied.com/article/item-18-free-text tags: contrails, air traffic control, ICAO, Vantis Air, forecasting genre: satire status: fiction — nothing in this story happened; every person, source and document is invented --- # The Contrail Fix Works. It Travels In Item 18, As Free Text. *Fourteen months, 3,114 requests to climb or descend around ice-supersaturated air. The diverted flights formed fewer lasting trails for 0.11 per cent more fuel. There is no box on the flight plan for asking.* Between March 2025 and April 2026, one airline asked one air navigation service provider to move 3,114 flights up or down to keep them out of ice-supersaturated air. Of those, 1,775 were approved. The approved flights formed measurably fewer persistent contrails than comparable flights that stayed where they were, and the extra fuel came to 0.11 per cent of the airline's block fuel across the whole period. The physics is not the problem. The form is. ## What the aircraft is being asked to do A contrail that lasts is not the same object as a contrail that vanishes. The short white line behind an aircraft on a dry day is ice that sublimates in seconds and warms nothing. The ones that matter form in ice-supersaturated regions: air already holding more water vapour than ice at that temperature can keep, waiting for something to condense onto. An aircraft supplies the something. The trail then spreads, thins into cirrus, and traps outgoing heat for hours. These layers are shallow. In this airspace over the fourteen months, the median supersaturated layer was about 1,900 feet deep. An aircraft cruising at flight level 350 that climbs or descends 2,000 feet is usually out of it. That is the entire proposition. Not spraying anything, not adding anything, not removing anything. Moving a small number of aircraft a small distance vertically for part of a sector. ## What the trial found We asked both organisations for the request records rather than the results, and joined them to the satellite detections ourselves. On the approved diversions, the detection product scored a persistent trail on 19 per cent of scored segments. On matched segments flown at the originally filed level, it scored one on 47 per cent. The fuel: 1.4 per cent more on the diverted sector itself, 0.11 per cent across all of the airline's block fuel in the period, because most flights were never diverted at all. Those are good numbers. They are the numbers the idea has needed for a decade. > **Figure:** One flight plan, eight fields, and the one field a machine cannot read — see https://theyburied.com/article/item-18-free-text ## Item 18 An ICAO flight plan has coded fields for almost everything. Aircraft type, wake category, departure aerodrome, cruising level, alternates — all of it in fixed characters that a machine reads without a person in the loop. There is no coded field for "I would like to be 2,000 feet higher because the air where I am is going to make a cirrus sheet." So it goes into Item 18, which is the free-text box. All 3,114 requests were filed there, as a string beginning CLIMATE/, with a median length of 141 characters, alongside remarks about catering uplift and unserviceable lavatories. A controller may read it. A controller may not. Nothing in the system requires it, flags it, or counts it. Of the 3,114, some 1,339 — 43 per cent — were refused for traffic. The dataset has a field for the refusal reason. It is filled in 61 times. > If it is in Item 18 I will see it when I have a second to look at Item 18. On that sector, some days, I do not have that second. > > — Ingemar Solheim-Adeyemi, area controller ## The two in three Here is the part that is worse for the trial than anything the form does to it. Of the 1,775 approved diversions, the satellite retrieval afterwards indicates that the originally filed level would not have produced a persistent trail on 1,171 of them. Roughly two diversions in three moved an aircraft out of air that would not have made a lasting trail anyway. The trial's own meteorologist disputes the word we first used for that, at length, at the foot of this page, and her objection is the best argument in this story. We had written "unnecessary". She points out that the supersaturated layers covered 11 per cent of cruise segments, that the product was aiming at real air 34 per cent of the time, and that scoring an avoidance decision against what subsequently happened is a standard nobody applies to de-icing or to lightning. She is right, and we have left our figure standing with her correction under it rather than quietly swapping the sentence. ## How it stopped No ruling ended this trial. No regulator, no objection, no finding. Dr. Marit Ekelund-Byrne built the daily supersaturation product and ran it alone for fourteen months. She went on parental leave in May. The product stopped being issued, because nobody else at either organisation had been trained to issue it. She told the airline in writing on 4 February, twenty-two weeks ahead, with a handover plan and three names. There was a budget line for the training. It was not spent. The trial is described by both parties as suspended rather than concluded. The working group next meets in November. ## What this desk takes from it We have spent eleven years on this desk [counting trails twice a day](/article/contrail-persistence-eleven-years) to establish that persistence is humidity. It is humidity. Somebody has now built a product that forecasts the humidity and an airline has flown against it and it works, at a fuel cost you would struggle to see in an annual account. The thing standing between that and the sky is a text box, a form with no field for the question, and a training course that nobody booked. ## Sources (invented) - The trial request-and-outcome dataset, 3,114 request records: filing time, requested level, disposition, controller sector, fuel uplift and burn — Requested jointly from the airline and the provider under a data-sharing letter that gave us no approval rights over publication (Released 26 June 2026) - Dr. Yewande Persson-Adigun, Atmospheric imaging group, Trondheim; built the contrail detection product used to score the trial — Interviewed by video call three times; supplied the detection validation figures and the recall number we print under Unverified (June and July 2026) - Ingemar Solheim-Adeyemi, Area controller, Nordluft ANS, twenty-six years; worked the trial's busiest sector — Interviewed in person during a rest break and again by telephone, with his employer's knowledge and no press officer present (July 2026) - Tobias Renner-Achebe, Head of flight efficiency, Vantis Air — Interviewed twice by video call; supplied the block-fuel denominators and confirmed the training position in writing (July 2026) - Dr. Marit Ekelund-Byrne, Meteorologist; built and ran the trial's daily supersaturation product alone for fourteen months — Sent the full draft with all figures and given three weeks; replied by letter (August 2026) ## What we could not confirm - Whether the fuel penalty holds at scale. The 0.11 per cent is across all of the airline's block fuel in the period, including the great majority of flights that were never diverted. On the diverted sectors alone we compute 1.4 per cent, and fourteen months did not include a full winter of easterly flow, which is when the deep supersaturated layers over this airspace do most of their work. - The contrail counts themselves. Satellite detection is poor at thin trails at night and at anything over bright cloud; the Trondheim group's own validation puts recall at 0.68 against a hand-labelled set. Every 'fewer trails' number in this story inherits that, and a detector that misses a third of trails could in principle be missing them unevenly between the diverted flights and the ones we compared them with. - Why 1,339 requests were refused. Traffic is the answer given, and it is entirely plausible on those sectors at those hours. But the reason field was filled in 61 times out of 1,339. We asked eleven controllers; four answered; four controllers are not a sample and we are not going to present them as one. ## Right of reply **Dr. Marit Ekelund-Byrne, meteorologist, formerly of the Vantis Air / Nordluft ANS contrail trial** (Replied by letter on 18 August 2026, asking that it run entire. Printed unedited.): > I will start where you are right, because you are right about the important thing and I do not want it lost in what follows. > > Item 18 is the whole problem. I have been saying so for three years to a working group that meets twice a year and has an agenda that runs to nine items. There is no coded field for a climate-motivated level request, so a thing we can calculate to within a couple of thousand feet has to travel to the person who decides it as a sentence in a box of sentences, underneath a note about catering. You have put that in a diagram and I am going to use your diagram, with credit, at the November meeting. Thank you. > > Now the rest. > > Two diversions in three were not unnecessary. Two diversions in three did not turn out to be needed, which is a different sentence, and the difference between those two sentences is the entire discipline I work in. > > Here are the numbers you had and did not use. Ice-supersaturated regions covered 11 per cent of the cruise segments in that airspace over the period. That is the base rate: file a level change at random and you would have been aiming at something real 11 per cent of the time. We were aiming at something real 34 per cent of the time. Three times better than chance, on a phenomenon whose vertical structure is a few hundred metres thick and whose forecast horizon is four hours. In any other application you would call that a good product. You have called it a two-in-three failure rate because you scored it after the fact against what happened, and nobody scores an avoidance decision that way. Nobody says the de-icing was unnecessary because the wing did not ice. Nobody says the lightning deviation was unnecessary because the aircraft was not struck. > > You of all people. Your author page carries the number of times you have been wrong — three thousand three hundred and eighty-eight, updated on Fridays — and I have quoted that page to graduate students as the honest way to publish a forecast. Then you write my product's misses as waste. Read your own page and then read your own paragraph and tell me the same person wrote both. > > And then there is the ending you have chosen. > > A fourteen-month trial with a seven-figure budget stopped because one person went on leave. You have written that sentence four times in this draft and each time the grammatical subject is me. It is not me. I notified the airline in writing on 4 February, twenty-two weeks ahead, with a two-page handover plan and the names of three people who could have been trained in six weeks. There was a budget line for exactly that. It was not spent. I asked again in March and in April. I have the emails and you have them too, because I sent them to you, and they appear in your story as the phrase 'had not trained a second'. > > So I would ask you to consider what you have actually described. Not a woman having a baby and a science project falling over. An organisation that ran a fourteen-month experiment on a single point of failure, was told so in writing five months in advance, had money set aside to fix it, and did not. That is the same failure as Item 18. It is the failure of a thing that works depending entirely on somebody remembering to do a piece of ordinary administration, and it turns out the atmosphere is the easy part. > > The daily product runs to 1,900 lines and it is documented. I left it documented. It is sitting where I left it. Somebody could run it on Monday. --- They Buried is a satirical newspaper. Every story, source, document and person in it is invented. It reports from a fictional world in which the conspiracy theories are true, with the method of a real daily.