Tail-diving passenger numbers, the long-delayed debut of a new jet and the ghost of Air France flight 447 haunts this week’s Paris Air Show. One of the commercial aerospace industry’s most prestigious events, the biennial show is celebrating its 100th anniversary with the industry facing grim economic numbers and the aftermath of the transatlantic crash of a Paris-bound Airbus A330 that killed 228 passengers and crew on May 31. The air show comes at a time when the commercial airline industry is facing its worst crisis in years.