Aircraft carriers already do half the job: EMALS catapults sling 33-tonne jets to 130 knots in 100 meters using linear induction motors. Flip the concept for civilian runways — a maglev sled that accelerates to match a landing plane's velocity, then decelerates together, capturing the kinetic energy regeneratively. Touchdown happens at zero relative speed. No screaming tires, no brake fires, no thrust reversers roaring at 3 a.m.

The energy budget. A Boeing 777-300ER touches down at roughly 250 km/h (69.4 m/s) with a landing mass around 180,000 kg. Kinetic energy:

KE = ½ · 180,000 · 69.4² ≈ 434 MJ

That's 120 kWh per landing — currently dumped as brake heat (carbon rotors regularly hit 600 °C) and reverse-thrust fuel burn. A regenerative maglev sled could recover 60–70% of it, ~85 kWh per landing. At Atlanta's 2,500 landings/day, that's ~215 MWh/day, or a modest 9 MW average — real, but the killer app isn't the electricity.

Sizing the sled. Say the sled masses 400 tonnes (steel deck plus superconducting bogies). To accelerate it from rest to 69.4 m/s before touchdown:

KE_sled = ½ · 400,000 · 69.4² ≈ 964 MJ

Over a 2 km acceleration run in ~30 s, average power ≈ 32 MW — inside the envelope of Ford-class EMALS (100 MW peaks from flywheel storage). After touchdown, combined mass ~580 t decelerating at a gentle 0.3 g (comfortable for passengers) needs:

d = v² / (2a) = 69.4² / (2·2.94) ≈ 820 m

So a 3 km sled track suffices — shorter than KJFK's 4L/22R.

Where physics bites back.

• Alignment. Crosswind landings involve a crab angle of up to 15°. The sled must yaw in real time, or the plane's gear pivots on touchdown. A ±3 m lateral maglev correction with 0.5 g cross-acceleration is doable but demands sub-second Kalman fusion of LIDAR, GPS-RTK, and pilot inputs.
• Go-arounds. If the pilot bails at the flare, the 400-tonne sled at 69 m/s has 964 MJ of momentum. Regenerative braking dumps that back into the flywheels — but a sled that can't stop before the runway end becomes a very expensive missile. Redundant induction brakes plus a passive eddy-current backstop are non-negotiable.
• Weather. Ice on the levitation gap (typically 10 mm for HTS maglev) is fatal. The rail needs heated aluminum stators — call it another 2 MW parasitic load in winter.
• Rejected takeoffs. Great news: the sled becomes a linear-motor arrestor, stopping a 200-tonne plane in <500 m regeneratively. This alone might justify the whole system for safety.

The real payoff isn't energy — it's runway length. Eliminate the flare-and-brake distance and a maglev-sled runway needs perhaps 1,500 m of touchdown zone instead of 3,500 m. That reclaims ~200 hectares at a major airport, worth billions in Manhattan-adjacent real estate terms. Brake and tire maintenance ($3M/year per 777 fleet-hour equivalent) drops toward zero. Community noise from thrust reversers vanishes.

Cost? EMALS runs ~$1B for a 100 m catapult. Scaling to 3 km linearly (a bad assumption, but a starting point) puts a single runway at $30B — roughly the cost of a new airport. So this only makes sense at capacity-starved megahubs like Heathrow or Haneda, where the alternative is a $50B sea-reclamation runway.