Flight School Update: Why We Do Run-Up Checks

So last night was interesting. I was doing more night circuits. Got in the plane, started it – it didn’t want to start but I figured, well it’s been sitting a couple hours since it’s last flight, it’s a cold start and I only primed it once.

As I was doing the rest of my start-up checks, I knew there was something not right. The engine wasn’t running rough, it just sounded weak. I glanced back at the tachometer, because usually you set it to 1000 rpm and then it rises as the engine warms up and you have to pull the throttle back a bit. Only it wasn’t going up, it was going down. I thought hmm, that could be a problem. Double checked my start-up checklist to make sure I hadn’t missed something that could cause it. But maybe it just needs warming up – we’ll see what happens in the run-up bay.

Taxied up to the hold short line at the end of the apron, and it was still doing the same thing, so I thought before I get all the way out to the run-up bay, lets see what happens if I pull he throttle to idle. And the engine died.

I started it up again, brought it back to the hangar and got another plane. That’s one of the nice things about Harv’s Air – they have like, 12 C-152s. But I know someone going to ask, didn’t that scare the bejeebers out of you, that it could have been in the air that happened?

And they’d be partly right – it’s not like that plane wouldn’t have flown if I’d tried to take off in it. It didn’t fail when I added power, it failed when I took it away. So if I’d taken off, it would likely have had enough power to take off, but would have failed in the circuit as I turned final to land – and chances are, that’ll be too far to quite make the runway at best glide, and too late to try and restart the engine.

But the reason I say it didn’t scare me is we do those run-up checks every time we take off, even if the plane’s only been on the ground, shut down, for a few minutes. One of the checks is pulling the power to idle. Even if I hadn’t been paying attention and noticed right away that there was something wrong, it would have failed in the run-up bay, before I ever tried to take off. I mean, sure, it’s possible a careless pilot might skip something and just take off, but it’s drilled into us enough times to do these checks, very few pilots would do that. (And the ones that would, probably don’t fly that long.) Even if nothing’s ever happened to them, there are stories of things happening to others, and those stories get passed around.

Aviation is kind of a study in risk management. Every time you go flying, you’re hoping the weather doesn’t turn bad at the wrong time unexpectedly, and the wind doesn’t change to give you a heavy crosswind at your destination, and a handful of other things you can’t control. So you make sure all the factors that are in your control and make sure they’re in your favour.

And that’s why we do run-up checks.