Why do you need to press so many buttons to start a plane? Can’t there be just one button to start everything in sequence automatically?
In: Technology
Pilot here. In a sense, a lot of the larger planes *are* “one button starts”, in that when everything is configured correctly, you simply turn a knob or push a button and the start sequence happens automatically.
The major difference between larger planes and cars is that, while cars can be started simply by the power from the battery alone turning over the engine, supplying fuel from the fuel pumps, and powering the spark plugs all at the same time, jet engines take a lot more “oomph” to turn over. They are far too heavy and need to turn at thousands of revolutions per minute before they gain enough speed to compress the air and begin the combustion process. Hence they are started with pressurized air rather than an electrically driven starter.
This air is typically supplied by a smaller jet engine in the back of the plane called an Auxiliary Power Unit which is small enough that it *can* be started with an electric motor. This smaller jet engine outputs enough pneumatic pressure to drive the larger jet engine and begin the combustion process. However, when it is broken or disabled, they can be started on the ground with a huge cart that is basically a giant fan that blows air into the engine and can get it going fast enough to begin the combustion process. If you have one engine running, it can also supply the air to the other engine. And in the *extremely* unlikely event that you lose *both* engines *and* the APU in mid-flight, the airplane can pitch down and glide fast enough to use the air blowing through the engines to start the combustion process. Pretty cool, right?
So in a way, when everything is working correctly, most larger airplanes are started with a two-button process- start the APU, then start the engines. The reason the airplane is so “configurable” and has so many buttons is primarily for troubleshooting and manually tweaking the systems in the event of a mid-air emergency. Unlike a car, when your engine quits or starts to overheat or something else, you can’t simply pull over and coast to a stop. You need to be able to isolate the affected systems and toggle them on or off as necessary. Also, if a giant computer controls all the systems and the computer itself has a problem (*cough* 737 MAX *cough*) you want to make sure you can manually and directly control the individual systems. Boeing takes the majority of the blame for the MAX design, as well they should, but there was a lot that went wrong on the pilots’ end of those crashes, too.
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