Danaher

The plane is at 6500 ft, 171.8 kt — probably on climb-out from a recent departure — with track 135.7°. The only ALIGNED candidate within Δhdg ≤ 25° is KIAH at bearing 136° (Δhdg 1°), perfectly aligned. KIAH is a recurring destination on Danaher's priors, fitting the business hub pattern. Distance of 1211 nm is consistent with a Falcon 900B's typical leg from anywhere (e.g., recent flights suggest this aircraft often hops between Western US and Bahamas; today it is SW Montana area, and a direct southbound leg to Houston is highly plausible). KMTJ at Δhdg 24°, 466 nm, is a recent visited field and a reasonable alternate if the aircraft is actually heading to Montrose, but the near-perfect track alignment to KIAH is stronger.