An Overview of Aerial Navigation, Part 2

(Part 1)

Flying the mail could be deadly in the late 1920s. Weather reports were sketchy and often hours old. A pilot might be flying along and, as the clouds descended, find himself “scud running.” Scud running is flying just below the base of the clouds, in low visibility and very close to the ground. Even back then, before the days of microwave and cellphone towers and other antennas everywhere, it was a good way to die. If a pilot flew into the clouds for more than a few seconds, without any instruments, he was as good as dead because he would lose control without any form of reference. So the pilots had to stay below the clouds and that meant scud running.

If you have ever driven the Merritt and Wilbur Cross Parkways in Connecticut, you may remember driving through a tunnel as the highway goes through a ridge line that runs from New Haven and north towards Meriden. That ridge line is along the direct air route between New York and Boston. The ridge line doesn’t look terribly high, but in the days of early airmail flying, quite a few pilots were killed when they were scud running and they hit that ridge. But there was one pilot who would fly over the clouds in Connecticut, and his name was Howard Stark.

By the late 1920s, there was one gyroscopically driven instrument, the Turn and Bank Indicator, in use.



Driven by a venturi, which sucked air past a set of vanes, which drove a little gyro, it would indicate if the aircraft was in a coordinated turn, but nobody realized how to use it to get out of a bad situation. Stark’s genius was that he devised a way to do that with that instrument, an altimeter and the airspeed indicator. He called it the “1-2-3 Method,” and this is how it worked:

1. Center the ball with the ailerons, then
2. Center the needle with the rudder, then
3. Control airspeed with the elevators. If you have the proper power set in and if you are going too fast, you will descend and if you are going too slowly, you will climb.

You could fly in clouds, safely, with Stark’s method. For decades to follow, legal instrument flight could be flown with just a Turn and Bank Indicator, an altimeter, an airspeed indicator, a magnetic compass and a watch. Even to this day, pilots training for their instrument rating must learn how to fly "partial panel," with only those tools.

But with only a magnetic compass and a watch, you could only navigate by dead reckoning, which meant that you could be some distance away from where you thought you were. So now that a pilot could control the aircraft, now a method of radio-based navigation was needed.

Stay tuned!