Blind Flying (Instrument flying)

Blind Flying means flying by reference to the instruments… blind flying is an outdated expression that now, is only used by the media to suggest that there’s something being done without knowing what the outcome is likely to be. In reality it’s nothing like that.

I’m often asked how I can see where I’m going in the dark or in clouds. Quite often fearful flyers are under the impression that if it’s a clear day I can see where I’m going and navigate accordingly. This isn’t unreasonable … it’s what we do in a car to navigate and keep clear of other traffic … we look out of the window to see how we’re doing. Even so, I can’t imagine that there’s anyone who really thinks that if I fly from London to Rome that I look out for the Eiffel Tower to see how I’m doing. Flying is much more accurate than that in every sense.

Every plane has an instrument panel. The instruments show speed, height and direction. There are other instruments that show navigational information. In our middle ear, there is a system which allows us to sense movement and in it’s simplest form tells us if we are nodding as in yes (in most languages), rotating our head as in indicating no and moving our head towards our shoulders, as in neck exercises. Because we cannot maintain balance without assistance from our eyes, when a plane is in a cloud or flying at night there is no way of knowing whether the plane is flying at the correct speed, height or direction because those senses are acted upon by forces that we don’t get when we are walking …with our eyes open. Try traveling in a car with your eyes closed …what is happening is very different from what you think and feel. Without going into the details of how the main instrument works, and the properties of gyroscopes I want you to recall the time when you held a spinning bicycle wheel and felt it wobble when you moved it. That odd movement is called precession.

Basic The Glass Cockpit Flight Management Systems

Following on from the main paragraph, a modern flight system certainly makes it a whole lot easier to fly to Rome in cloud, because instead of ‘working it out’ from radio beams you can see a visual and geographic representation of the outside world. It’s like a three-dimensional car sat-nav display.

In a plane when you’re a passenger you have no instruments to tell you which way is up or what the plane is ‘doing’. It’s possible and quite normal for you to feel perfectly level when the plane is in fact turning and similarly to imagine you’re turning when you are flying level. I’m sure you know that these ‘feelings’ can mislead you into thinking that just after take-off when the power is reduced … that you’re going down!

This is a very, very basic explanation of how we ‘feel’ in a plane. Pilots learn from day one to ignore what they ‘feel’ and believe their instruments. This is the reason that although you can feel the plane’s movements you can’t actually tell what it’s doing when you’re in cloud or at night. No, you really can’t.

I want now to move on to the advantages of the modern instruments because I shall finish this article by saying that the Flight Management system can be connected to the autopilot and the whole flight can be managed through one system.
Earlier I spoke of the bicycle wheel and it’s funny wobbling properties … that is a very basic form of gyro and the way we can get information from a gyro is to hold it in place with springs so that instead of moving, we can measure the force in the spring and work out what it would have done if it hadn’t been restrained.

Well it’s very easy to turn that force into electricity and measure the voltage or current or whatever it is we can measure and determine what the gyro would have done if it wasn’t held in place by magnets … or some other electrical force, and so we go on getting more and more sophisticated until we have a completely automatic …

Where is all this leading us? Towards a wonderful safety feature that is on all modern aircraft.

What we can do now is show the pilots which way the numbers are moving without him having to watch them. In other words, if the speed of the plane is reducing … the electronics can measure how quickly it’s changing AND then show a pointer saying ” if you carry on like this for another 15 seconds the speed (or height, or anything else) will be this much”.

After this, it goes from strength to strength because you can build in warnings that say “with the flaps in this position, your maximum speed is this much and your minimum speed is that much.” And this provides a perfect back up and warning in case the pilot and his/her co-pilot didn’t spot it! The designer can even get the thing to make warning noises if it’s an important enough event, like approaching the stall or exceeding the speed limit for the ‘configuration’.
But why stop at this level? Why not show when the plane can climb higher or even where it should start its descent towards the destination airport. Why not include information about what the autopilot is doing? Actually, we need to limit the amount of information that we give the pilot in case all this help overloads him/her. Hey, I’ve just had an idea. Rather than allow the autopilot to do what we tell it to do like change direction or height, why don’t we connect it to the system that is providing all this information, especially if we can programme the route into it? Indeed we start the flight by programming all this information into what is unsurprisingly called the Flight Management Computer. And this determines where and how the aircraft flies the route that we select. And we’ll have another safety measure here; the routes are agreed by Air Traffic Control … and they are updated monthly.

We have moved a long way from the notion of ‘blind flying’ to a fully integrated flight management system that greatly enhances flight safety. And that is what the original statement implied; that blind flying is unsafe. When talking about flying, anxious flyers should describe flying in the clouds or at night as flying with reference to the flight instruments. However, it’s worth remembering that all commercial aircraft are flown by reference to the instruments at all times anyway!

Best wishes,

Captain Keith

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