Here is Heathrow's 2025 proposal. A third runway, 3.5 kilometres long, north-west of the airport, with the M25 motorway moved into a tunnel. Flights from 480,000 to 756,000 a year; passengers from 84 million to 150 million. Runway and airfield £21 billion; the whole plan £49 billion. The government set 2035 for first flights; the airport reportedly now expects 2039.
Count→Baseline→Scope→Multiply→Map and subtract
This lesson says nothing about whether it should be built. That is not a count, and this course only does counts. What it does is take the proposal apart with the tools the course gave you, one step at a time, so that each sentence in the argument lands on a number you can check.
New flightsairline-owned
↓→
Heathrow's countscope 3, in the air
Tool one, scope. The runway's new flights would be flown by airlines. Where do they land in Heathrow's count?
Nowhere. The airlines count them.
Not yet. The airlines count them too. Scope 3 is shared, and Heathrow has chosen to count every departure's full flight.
Scope 1, because the runway is Heathrow's.
Not yet. The runway is concrete, and building it is scope 3 supply chain. The flights that use it burn airline fuel in airline planes: scope 3 as well.
Scope 3, in the air, the whole flight out: Heathrow counts flights it does not fly.
Right. Lesson 3's rule. The airport owns neither plane nor fuel and counts the cruise anyway. New flights from a new runway go into the same 96 in 100.
Tool two, the multiplication. Set the flights and the carbon per flight. The figure is total flight carbon against 2019 = 100.
2019100
This setting85
Flights a year: 480,000 · Carbon per flight against 2019: Down 15 in 100
480,000 flights, each down 15 in 100: total 85 against 2019's 100. Below the baseline.
2019100
This setting70
Flights a year: 480,000 · Carbon per flight against 2019: Down 30 in 100
480,000 flights, each down 30 in 100: total 70 against 2019's 100. Below the baseline.
2019100
This setting50
Flights a year: 480,000 · Carbon per flight against 2019: Down 50 in 100
480,000 flights, each down 50 in 100: total 50 against 2019's 100. Below the baseline.
2019100
This setting110
Flights a year: 620,000 · Carbon per flight against 2019: Down 15 in 100
620,000 flights, each down 15 in 100: total 110 against 2019's 100. Above the baseline.
2019100
This setting90
Flights a year: 620,000 · Carbon per flight against 2019: Down 30 in 100
620,000 flights, each down 30 in 100: total 90 against 2019's 100. Below the baseline.
2019100
This setting65
Flights a year: 620,000 · Carbon per flight against 2019: Down 50 in 100
620,000 flights, each down 50 in 100: total 65 against 2019's 100. Below the baseline.
2019100
This setting134
Flights a year: 756,000 · Carbon per flight against 2019: Down 15 in 100
756,000 flights, each down 15 in 100: total 134 against 2019's 100. Above the baseline.
2019100
This setting110
Flights a year: 756,000 · Carbon per flight against 2019: Down 30 in 100
756,000 flights, each down 30 in 100: total 110 against 2019's 100. Above the baseline.
2019100
This setting79
Flights a year: 756,000 · Carbon per flight against 2019: Down 50 in 100
756,000 flights, each down 50 in 100: total 79 against 2019's 100. Below the baseline.
With the full runway, what cut per flight brings the total back below 2019?
Down 15 in 100 per flight: roughly what the 2030 target needs at today's flight numbers.
Not yet. That frame reads 134. The target is a cut in total tonnes, set with flights capped at 480,000; with 58 in 100 more of them, 15 per flight leaves the total a third above the baseline.
Down 50 in 100 gets to 79. Down 30 lands at 110, still above.
Right. At 756,000 flights the total is 1.575 times today's 480,000 cap. Only a cut bigger than 36.5 in 100 per flight brings it under 100, and 50 is the first setting that does.
Down 30 in 100.
Not yet. That frame reads 110: close, and still above 2019. The break-even cut at full runway is about 36 in 100 per flight.
Move both controls.
Homes to the northnow inside the line
++
People count at 756,000 flightsstill to come
Tool three, the line on the map. More flights means more people inside the noise contour, unless planes get quieter faster than they get more numerous. The new runway also moves the line: homes to the north that were outside it would be inside. A people count for 756,000 flights is part of the planning application still to come.
Tool four, the ground. Tap the ground source a decade of building does most to.
Tap the part of the picture that answers it.
Supply chain266 thousand tonnes, 2025
Passengers' journeys398 thousand tonnes, 2025
Own boilers and vans27 thousand tonnes, 2025
Supply chain
Right. Concrete and steel, counted as bought goods. Years of runway, tunnel and terminal building would put this well past any level in the report, and the 45 in 100 ground target with it.
Passengers' journeys
Not yet. Journeys rise with passengers, later, once the runway is open. During the building years, the pour of concrete is the source that moves first.
Own boilers and vans
Not yet. The boilers heat the terminals that exist. Building adds little to them; the carbon of building is in the supply chain.
More flights: counted→SAF to 22 in 100: a rule→Newer planes: slow→Taken out of the air: uncertain→Net zero 2050: a promise
Tool five, the subtraction. Heathrow's answer to the multiplication is the 2050 net zero sum: more SAF, newer planes, and whatever is taken out of the air by then. The SAF side is a rule up to 2040, 22 in 100, with most of the factories not yet built. The taking-out side is the least certain count in the course.
Each sentence is from the argument about the runway. Is it a count that exists today, or a promise about a future count?
One card at a time. Tap the pile it belongs to.
Card 1 of 6
Flights would rise from 480,000 to 756,000
Flight carbon will be 15 in 100 below 2019 by 2030
Flight carbon in 2025 was 18.6 million tonnes
Flights from Heathrow will be net zero by 2050
46 in 100 of passengers arrive by public transport
At least 55 in 100 will arrive by public transport at 130 million passengers
Flights would rise from 480,000 to 756,000 → A count today
Not yet. A count today: it is the plan's own number, on paper now.
Flight carbon will be 15 in 100 below 2019 by 2030 → A promise
Not yet. A promise. Seven in 100 has arrived; the rest depends on planes bought and fuel made.
Flight carbon in 2025 was 18.6 million tonnes → A count today
Not yet. A count today, in Heathrow's own data book, checked by its accountants.
Flights from Heathrow will be net zero by 2050 → A promise
Not yet. A promise, resting on fuel supply and removals that nobody can count yet.
46 in 100 of passengers arrive by public transport → A count today
Not yet. A count today, from Heathrow's survey; the government's survey says 41, which is also a count today.
At least 55 in 100 will arrive by public transport at 130 million passengers → A promise
Not yet. A promise, written into a draft rule. The number exists; the arrivals do not.
3Counts today
vsvs
3Promises
Right. Three counts, three promises. A proposal is argued with both, and the sentences sound alike. The course's last skill is hearing which is which.
Count
++
Baseline
++
Multiply
++
Next door
That is the whole course, used once. A footprint is a count. A target is a cut from a baseline somebody chose. Scope says whose smoke is counted. Total is flights times carbon per flight. Noise and dirty air are measured in people and in readings, next door. Net is a subtraction, and its two sides have different proof.
On trackper flight, from 2019
vsvs
Plus 58 in 100 flightsthe skipped step
A friend says: Heathrow is on track for its climate target, so the runway is fine for the climate. Using the course, what is the most accurate reply?
The target is a cut in total flight carbon from 2019, set with flights capped at 480,000. A runway adds 58 in 100 more flights, so on track today says little about the total with it.
Right. Every word of the friend's sentence is true, and the conclusion does not follow. The target was set for today's flight numbers; the multiplication is the step the sentence skipped.
The target is a lie.
Not yet. The target is a real cut from a real baseline, and 7 in 100 of it has arrived. The problem is not the target; it is applying it to a different number of flights.
The runway's carbon does not count, because airlines fly the planes.
Not yet. Heathrow counts every departing flight's whole journey as its own, in the air, scope 3. The new flights would be in its count on the day they take off.
Lesson complete
Count, baseline, scope, multiply, a line on a map, subtract: that is how to read a runway.