MIflyer
1st Lieutenant
Not long before WWII broke out the RAF was sending some new Blenheims to Egypt. On one aircraft an extra pilot was assigned as a navigator. They were fly across the Channel, across France, refuel in southern France on the coast, and then proceed to Egypt. The flight was somewhat fraught with danger because they had to steer well clear of Spain. No one was shooting at anyone in Europe yet but they could be intercepted by unfriendly BF-109's if they strayed near Spain.
The pilot serving as navigator plotted the course, noted their takeoff time, and proceeded to check their progress against expected landmarks so that the course could be confirmed and adjusted accordingly. But after they were over France he noted that the expected landmarks were not coming up on the expected schedule. Puzzled, he started looking for the source of the problem. What he found horrified him.
Most aircraft of that era were equipped with altimeters with only one needle. If the the altimeter needle pointed about halfway between "1" and "2" you knew you were at around 1500 feet, and so forth around the dial. Determining an altitude of about, say, 1550 ft accurately was just about impossible.
But the Blenheim had a new innovation, what was called a "Sensitive" altimeter. It had two needles of different length, one for thousands of feet and and one to indicate hundreds. On some altimeters there was even a separate scale for hundreds and thousands.
The pilot acting as navigator had noted the time of takeoff and other checkpoints by looking a the clock on the instrument panel. But being unused to the new style altimeters, he had mistaken it for a clock! He confessed his mistake to the other pilot and as a result they altered their course further to the East to make sure they missed Spain. They were eventually able to sight a good landmark and find their refueling airfield.
Some years ago I acquired an old altimeter by taking it out of a trashcan and took it up in my airplane to compare it to one already installed. I concluded that the thing had been in the trash for a good reason; it was way off. But later I realized it had the separate scales for thousands and hundreds, and given that, it was not too far off. But at least I did not think it was a clock.
The pilot serving as navigator plotted the course, noted their takeoff time, and proceeded to check their progress against expected landmarks so that the course could be confirmed and adjusted accordingly. But after they were over France he noted that the expected landmarks were not coming up on the expected schedule. Puzzled, he started looking for the source of the problem. What he found horrified him.
Most aircraft of that era were equipped with altimeters with only one needle. If the the altimeter needle pointed about halfway between "1" and "2" you knew you were at around 1500 feet, and so forth around the dial. Determining an altitude of about, say, 1550 ft accurately was just about impossible.
But the Blenheim had a new innovation, what was called a "Sensitive" altimeter. It had two needles of different length, one for thousands of feet and and one to indicate hundreds. On some altimeters there was even a separate scale for hundreds and thousands.
The pilot acting as navigator had noted the time of takeoff and other checkpoints by looking a the clock on the instrument panel. But being unused to the new style altimeters, he had mistaken it for a clock! He confessed his mistake to the other pilot and as a result they altered their course further to the East to make sure they missed Spain. They were eventually able to sight a good landmark and find their refueling airfield.
Some years ago I acquired an old altimeter by taking it out of a trashcan and took it up in my airplane to compare it to one already installed. I concluded that the thing had been in the trash for a good reason; it was way off. But later I realized it had the separate scales for thousands and hundreds, and given that, it was not too far off. But at least I did not think it was a clock.
