Given that we're unlikely to see commercial flight electrified in any realistic timeline and the high carbon footprint per flight in the meantime, seeking out alternative fuels like ammonia is quite attractive. 

Making hydrogen requires hydrocarbons for practical applications and still isn’t up to scale, for example, so using just some hydrogen, again, gives this plan an edge. For now, the feasibility report is just a key to open the next door.

This part is intriguing as well-- seems you can start fuel mixing to get lower carbon energy incorporated sooner rather than needing to weight for fully decarbonized fuels? That's a good near-term option