Today, communicating and navigating for planes is all done by computers, satellites and GPS. But during the flying boat era in the 1930s and 1940s it was a totally different story, literally navigating by the sun, moon, and stars.
There are difficulties navigating over featureless expanses of water for thousands of miles, and the weather, especially in the North Atlantic Ocean is often unpredictable and violent. To help the flying boats navigate, there were a number of items of equipment used.
When you are flying in an enclosed airplane, it is difficult to know the strength and direction of the wind. In the days of flying boats, there was no equipment to tell the navigator this information, so the navigator every so often would toss smoke bombs from the plane that would burn on the surface of the sea that would allow him to measure the drift. In those days planes flew much lower than modern aircraft which can fly much higher in the sky.
The setant is a device that was used by both slying boats and ships. The navigator would use it to take measurements from the sun during the day, and from the moon and stars at night–provided the sky was clear! From these measurements, the navigator would use a map and a series of mathematical formulae to calculate their position on a map.
Essentially, dead reckoning was guessing your location based upon your last know location, your direction based on compass reading, your estimated speed and the time that had elapsed since your last know location. Not an ideal form of navigation, but used as a guide none the less.
Radio communication was available, but it wasn’t verbal, it was though the use of morse code. Morse code is a series of long and short tones. Each letter and number had its own specific code. For example, A was a short tone followed by a long tone,•–, B was a long tone followed by three short tones, –•••, S was three long tones, – – –, and O three short tones, •••, etc. The information transmitted from the plane was generally updates on fuel and location, and from base, information on weather.
After all this work, if the weather was too bad, or head winds too strong resulting in greater fuel consumption than the flight required, panes often had to turn back half way through their 24 hours journey!