Sir William Hildred drew upon his personal experiences until 1966 as Director General of the International Air Transport Association.

That body worked closely with the International Civil Aviation Organisation (ICAO)—the author, instigator, and watchdog of Annex 9 of the Chicago Convention which dealt wholly with the subject of facilitation. Neither body had legislative power. ICAO could only make recommendations but these required the assent and action of Sovereign Governments before they became effective. The President of ICAO had said it was the increase in passenger and cargo volume which created the problem but Sir William ascribed a good deal of it to the entrenched conservatism of Governments and their operating agencies.