There was the second moment, during which Daddy Jacques was absent and Monsieur Stangerson was left alone before the door.

There was a third moment, when Monsieur Stangerson was joined by the concierge.

There was a fourth moment, during which Monsieur Stangerson, the concierge and his wife and Daddy Jacques were before the door.

There was a fifth moment, during which the door was burst open and The Yellow Room entered.

The moment at which the flight is explainable is the very moment when there was the least number of persons before the door.