In short, the two combine much of the young Shute as he described himself in Slide Rule. In the first Stephen Morris is initially involved as a pilot with 2 others in a scheme to take tourists and holidayers on joyrides. When that packs up he tries to get into avaiation design. Along the way he meets a girl he would like to marry but having no money gives the idea a pass. He thinks she has married someone else but in the end it turns out she waited for him.
Pilotage is more of the same, sort of.
Peter Dennison wants to get married but does not feel that he has enough money. He takes a job in Hong Kong but his intended refuses to go, although she wants to marry him as well. Through various turns of events Dennison meets Stephen Morris who is looking for a navigator. Morris, now a successful designer and pilot is involved in a scheme to fly mail halfway across the Atlantic. The idea is that a small plane will be carried on a ship and, about 1,000 miles from England, will be launched.