MechJeb Spaceplane Orbit to Runway Script

--
--         Shuttle Autopilot Library by olex
--                    Version 1.0
--
--                 for MechJeb 1.9.1
--
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-- Usage: * save to KSP/PluginData/mumechlib/Shuttle.lua
--        * in game, open autom8
--        * enter: dofile("Shuttle.lua")
--        * and follow the instructions.
--
-- Quicksave before using any of the functions.
-- If an "coroutine out of sync" error pops up, load the save and try again.
--
-- No guarantees, but it should work :) Have fun!
--------------------------------------------------------
function PlaneLandingDriver(slope, offset)
    -- KSP coordinates
    lat = -0.103
    lon = -74.575

    -- "undershoot" offset and glide slope
    if (offset == nil) then
        offset = 40 -- default offset of 40km
    end
    lon = lon - (offset / 10) -- 1° ~= 10km near the KSP

    if (slope == nil) then
        slope = 3 -- default ILS glide slope of 3°
    end

    -- start re-entry sequence
    print "Deorbiting..."
    mechjeb.landAt(lat, lon, false)

    -- at 75km: cancel powered landing sequence, set attitude for aerodymanic flight, wings level
    wait(function() return (vessel.altitudeASL <= 75000) end )
    print "Beginning re-entry, hold onto something..."
    mechjeb.controlRelease()
    wait(3)
    mechjeb.attitudeTo({0,0,0,0}, "ORBIT")

    -- at 15km: engage the ILS
    wait(function() return (vessel.altitudeASL <= 15000) end )
    print "Initiating ILS approach, please lower landing gear manually."
    ils = mechjeb.getModule("ils")
    ils.glideslope = slope
    mechjeb.ilsLand()

    -- at 2m (immediately before touchdown)
    wait(function() return (vessel.altitudeTrue <= 2.5) end )
    print "Touching down, deploying braking parachutes (if you have any)..."
    mechjeb.controlRelease() -- stop ILS sequence
    mechjeb.attitudeTo({1,0,0,0}, "SURFACE_NORTH")
    mechjeb.stage() -- in case there actually are braking chutes

    -- at <5 m/s, we're done
    wait(function() return (vessel.speedSurface < 5) end )
    print "Welcome home. You can hit the brakes now."
    mechjeb.controlRelease()
end

function Land(slope)
    local co = coroutine.create(PlaneLandingDriver)
    coroutine.resume(co, slope)
end

print "Usage: Land(<glideslope, default 3°>, <glide distance offset, default 40km>)"