RTO Stop distance calucaltor Tool A350 (or any airliner)

    I will upload all my modding tools to my website once it's complete:google drive link for now - https://drive.google.com/file/d/1A5OAre…iew?usp=sharing


    I created this tool whilst testing the RBCU / CPIOM: (Remote Braking Control Units and Core Processing Input/Output Modules). I have built the 4 computers on the A350 and redesigned the braking system, after around 200 RTOs; everything is behaving very realistically, including brake temperatures and worn condition affecting stopping distance.

    This tool actually works with any aircraft, so I have included it for other modders looking to tweak the numbers

    It reads the telemetry from the DLL. The A350 by default was actually extremely close to the real aircraft as far as stopping distance without reversers; the changes I made were for the various computer faults, and HYD failures, which increase stopping distance

    Thankfully, I found a university study on the A350-1000 stopping distances, with all the data required.


    Full list of braking functions simulated. Again, a proof of concept, but the level of depth this sim is capable of never ceases to amaze me. The mind appears to be the limit.



    A350 Advanced — Brake System Simulation

    Display Spoiler

    The A350 Advanced braking system has grown into a fairly extensive physical simulation. Most failures are interconnected with hydraulic supply, brake computers, temperature, accumulator state and actual stopping performance rather than simply displaying an ECAM message.

    • Normal braking
      • Green hydraulic system supplies normal braking.
      • Pedal input controls actual wheel-brake demand.
      • Normal brake authority calibrated against repeated heavy-weight RTO testing.
      • Hydraulic pressure indication is now separated from actual wheel braking effectiveness, so the cockpit can show full commanded pressure even when brake effectiveness is degraded by temperature or failures.
    • Alternate braking
      • Yellow hydraulic system provides alternate braking following loss of normal braking.
      • Has its own reduced braking authority rather than simply duplicating normal braking.
      • Existing stopping-distance differences between Normal and Alternate braking remain intact.
    • Emergency braking
      • Emergency/manual braking path modeled separately.
      • Uses Yellow-system/accumulator availability.
      • Remains available after several severe brake-computer combinations where normal digital braking has been lost.
      • Accumulator pressure and remaining applications matter.
    • Parking brake
      • Powered from Yellow accumulator pressure.
      • Can eventually lose effectiveness as accumulator pressure is depleted.
      • Parking brake operation contributes to accumulator consumption.
      • Amber/low accumulator indications are connected to actual accumulator state.
    • Brake accumulator
      • Stores braking energy when Yellow hydraulic pressure is unavailable.
      • Approximately 4–5 useful brake applications modeled from a charged accumulator.
      • Recharges when suitable Yellow hydraulic pressure becomes available.
      • Low accumulator pressure affects parking/emergency braking availability.
    • Autobrake
      • Depends on the appropriate brake-system availability.
      • RTO behavior supported.
      • Autobrake removed when relevant brake-control failures make automatic braking unavailable.
      • Dual BRAKES CTL failure forcibly disengages AutoBrake.
      • Re-arm protection means MED/RTO/BTV cannot simply be selected again while the dual BRAKES CTL failure remains active.
    • BTV / Brake To Vacate
      • Treated as dependent on the automatic brake-control architecture.
      • Dual BRAKES CTL failure produces BTV FAULT.
      • BTV cannot remain armed after the corresponding control-system loss.
    • Anti-skid
      • Anti-skid system availability is connected to braking.
      • Anti-skid loss affects normal braking and related indications.
      • Further A350-specific work is planned to model the documented all-wheel anti-skid-loss brake-pressure limitation more accurately.
    • Nose-wheel steering dependencies
      • NWS availability is linked to the relevant hydraulic/braking-system state.
      • Brake and hydraulic failures can therefore produce realistic steering knock-on effects.
    • Brake temperature simulation
      • Twelve individual brake-temperature indications.
      • Left/right brake groups heat independently.
      • Uneven individual wheel temperatures are represented.
      • Temperature increases according to:
        • brake application
        • ground speed
        • wheel loading
      • Passive cooling is modeled.
      • Brake-fan cooling is modeled separately.
      • Airborne cooling increases after takeoff.
      • Cooling has been tuned from high-temperature tests rather than simply dropping temperatures rapidly.
    • BRAKES HOT
      • Generated from actual simulated brake temperatures.
      • Can result naturally following heavy braking/RTO operation.
      • Cooling fans materially affect recovery time.
    • Temperature-dependent carbon brake fade
      • Brake temperature now changes actual stopping effectiveness.
      • Normal/warm carbon brakes retain full effectiveness.
      • Fade begins only at very high temperatures.
      • Current physical curve:
        • up to 600°C — 100%
        • 650°C — 95%
        • 700°C — 90%
        • 800°C — 75%
        • 900°C — 55%
        • 1000°C — 35%
      • The pressure indication remains independent, meaning full brake pressure may still be indicated while overheated brakes produce substantially less braking torque.
      • Fade applies downstream of Normal, Alternate, Emergency and Parking brake demand.
    • Heavy-weight RTO calibration
      • Dedicated telemetry tool built for repeatable brake-performance testing.
      • Benchmark around 322 t and ~173 kt.
      • Clean, no-reverse reject-to-stop result approximately 1,396 m.
      • Mean deceleration approximately 0.290 g.
      • Maximum reverse reduced stopping distance by roughly 280 m in the paired test.
      • Brake and reverse calibration were deliberately left unchanged after these results because performance was already credible.
    • Remote Braking Control Units — RBCUs
      • Four independently selectable digital channel failures:
        • Remote Brake Control 1A
        • Remote Brake Control 1B
        • Remote Brake Control 2A
        • Remote Brake Control 2B
      • Single-channel failures are modeled as redundancy degradation rather than arbitrarily removing a quarter of the brakes.
      • Correct STATUS/inoperative-system indications.
    • Dual RBCU failures
      • 1A + 1B
      • 2A + 2B
      • Same-unit A+B failures produce genuine physical braking degradation.
      • Current calibrated authority approximately 78% of clean normal braking.
      • This was validated in an actual RTO:
        • 322 t
        • 173.4 kt reject GS
        • 1,778 m reject-to-stop
        • 0.228 g mean deceleration
      • The measured deceleration ratio was ~0.786 versus the intended 0.78 model.
    • Cross-RBCU dual failures
      • 1A + 2A
      • 1B + 2B
      • Correct channel/status failure combinations available.
      • They currently avoid invented physical penalties where we do not have enough Airbus information to justify one.
    • Timed RBCU failures
      • RBCU faults can occur naturally after becoming airborne rather than always being present from engine start.
      • Uses a proven airborne timer → latch architecture.
      • Available as timed singles and duals.
      • Late-flight variants allow failures to occur naturally in cruise or descent.
      • Current late-flight examples include approximately 45, 60, 75 and 90 minutes airborne.
    • Triple RBCU failures
      • Four channel combinations supported:
        • 1A + 1B + 2A
        • 1A + 1B + 2B
        • 1A + 2A + 2B
        • 1B + 2A + 2B
      • Timed airborne activation.
      • Latched once failed.
      • Physical braking effect depends on the surviving channel architecture.
      • Approximate targets are around 60% where a useful B-channel backup remains and around 50% for more severe triple combinations.
    • Quad RBCU failure
      • 1A + 1B + 2A + 2B.
      • Timed airborne/latched failure.
      • Does not simply produce zero brakes.
      • Retains the conceptual RBCU E-channel emergency braking path.
      • Current physical target approximately 35% of clean normal braking.
    • BRAKES CTL 1 / BRAKES CTL 2
      • Separate brake-control-computer failures.
      • Single BRAKES CTL failure represents loss of redundancy because the surviving controller automatically becomes the backup/active controller.
      • Therefore a single fault does not artificially reduce brake torque.
    • BRAKES CTL MEL dispatch
      • Single BRAKES CTL 1 or BRAKES CTL 2 failures can be loaded as ground/MEL dispatch conditions.
      • The simulated aircraft can therefore depart with one controller inoperative while the redundant system remains available.
    • Timed airborne BRAKES CTL failures
      • BRAKES CTL 1 and BRAKES CTL 2 can also fail after becoming airborne.
      • Timed and latched rather than merely being immediate startup faults.
    • Dual BRAKES CTL failure
      • Airborne-only — not treated as an MEL-dispatch configuration.
      • Both BRAKES CTL 1 and BRAKES CTL 2 shown failed.
      • AUTO BRK FAULT.
      • BTV FAULT.
      • Automatic braking is forcibly disengaged.
      • Attempts to re-arm it are rejected while the fault remains active.
      • Manual pedal braking remains available through the RBCU/direct-pedal architecture rather than incorrectly turning this into complete brake loss.
    • Hydraulic failure interaction
      • Green-system failure removes/degrades normal braking.
      • Yellow-system failure affects alternate/emergency/parking capability.
      • Combined hydraulic states therefore change which braking mode is actually available.
      • RAT/emergency hydraulic/electrical states also interact with the system.

    • Brake failure indications

      • Green/Yellow system low pressure.
      • Accumulator low.
      • Normal/alternate brake degradation.
      • Anti-skid loss.
      • NWS loss.
      • Remote Brake Control channel failures.
      • BRAKES CTL failures.
      • AutoBrake/BTV inoperative status.
      • BRAKES HOT.


      • all-wheel anti-skid pressure limiting
      • residual/dragging individual brake
      • brake temperature sensor XX
      • brake pressure-transducer failures
      • selector/servo-valve redundancy failures
      • thermal fuse-plug melting
      • tyre deflation following sustained extreme brake temperature
      • increased rolling resistance from deflated tyres

  • 777Driver August 17, 2026 at 4:35 PM

    Changed the title of the thread from “RTO Stop distance calucaltor Tool A350” to “RTO Stop distance calucaltor Tool A350 (or any airliner)”.