What on your aircraft could kill you?

Well the first mantra is Aviate Navigate Communicate, so levelling off is a priority and any distractions should be on stand by. Most altitude bugs will advise 1,000 feet to go, which should prime you to monitor that the AP is capturing the pre set altitude. Then it’s a matter of calling out at 200’ to go, 100’ feet to go, Capture displayed and confirming it has levelled off in ALT mode, with the correct power set.

Similar to countdown to minimums, except pilots may not be trained to treat level offs in the same way. Until they get the ’phone call for a level bust.

On the IR I think you just have to demonstrate HDG mode in the level cruise. I still see people punching NAV when not on an intercept and wondering why nothing is happening.

There are several topics mixed up here. There are things you as a pilot can do in a particular type which can kill you. The trim as mentioned above and the hydraulic control lock as mentioned in the well known GIV crash at Bedford.

Then there are things which will get you if the omit to mis set them and then something goes wrong. Failing to switch on Auto Feather on a modern King Air falls int this category.

Then there are things that you can do in any aeroplane….

Mooneys will distinctly put the nose down when applying flaps, so you have to trim up considerably to have her fly an approach at say 80 knots and full flaps. If you have to go-around and apply full power and retract the flaps you’ll need a lot force and push forward very hard. Otherwise she will put the nose high into the sky and stall. This behaviour is much more pronounced than on other types I know and does require some type specific training. Actually a number of people have in fact been killed by this.

And this is on certified aircraft… I wonder what this thread would look like in Non Certified?

Speaking of a kind-of type specific issue, there is that famous Cessna 182 (?) takeoff crash where the autopilot was close to the throttle, and when the pilot went full power on takeoff, he pressed the AP button and this engaged the autopilot, which trimmed the elevator trim all the way back, causing the plane to pitch up when it reached enough speed, stall, and crash, killing both occupants (who were both experienced pilots).

On that particular type it was not possible for even two people to apply enough forward force, at Vs, when the elevator trim was would all the way back. I wonder how many GA types this applies to? I have read that on airliners that would be a 100% sure crash.

But also the autopilot installation, at the bottom of the stack, was thought to be unusual.

The other installation-specific factor is that the autopilot would engage while on the ground. However I don’t think any GA installation is linked to the squat switches, or airspeed.

Peter wrote:

However I don’t think any GA installation is linked to the squat switches, or airspeed.

Not in a way that you can’t engage the AP on the ground (you actually want to be able to do this in order to test the AP as part of the before takeoff checks). But of course there are autopilots like the GFC 700 or DFC90 with IAS as an input. They wouldn’t pull you into a stall even if activated accidentally with completely wrong preselections.

Then you don’t need an autopilot for this way of killing yourself. You can have a trim runaway just with an electrical trim.

petakas wrote:

- Descend on autopilot above terrain by missing to ARM the set altitude capture while flying near terrain in IMC

The ARM should appear automatically whenever the altitude preselect is changed,

There is a nasty “feature” of the KAP140. If you change the altitude preselect, it will ARM altitude capture, but only if the A/P is engaged already. This may be a common behaviour of autopilots, but it has caught me out a couple of times when I’ve set the cleared altitude in the A/P before takeoff. This is of course in the climb and then a level bust is unlikely to kill you, but the same thing could happen on descent.

The ENGINE MASTER switch in the DA40 could kill you.
It is a tumbler switch which turns off the engine instantly.
There is some protection in that you need to pull the switch while moving it, but the needed force is very little.

There was a deadly crash with a DA40 in Russia in 2014 where the pilot accidentally switched off the engine instead of the fuel pump after takeoff.
The picture below is from the accident report and clearly shows the bad ergonomic design:

If you change the altitude preselect, it will ARM altitude capture, but only if the A/P is engaged already

That is standard. If the AP is not engaged, there is nothing to “arm”.

On the KFC225, you can twiddle the preselect altitude all over the place, when the AP is not engaged. All it does is give you the “leaving altitude” when you depart from it by 200ft.

Not in a way that you can’t engage the AP on the ground (you actually want to be able to do this in order to test the AP as part of the before takeoff checks). But of course there are autopilots like the GFC 700 or DFC90 with IAS as an input. They wouldn’t pull you into a stall even if activated accidentally with completely wrong preselections.
Then you don’t need an autopilot for this way of killing yourself. You can have a trim runaway just with an electrical trim.

That is the key Q: can you engage the AP on the ground (whether moving or not) in a way which makes it drive the trim?

On my KFC225 you can engage it (as pointed out, this is required to test the AP before every flight anyway) but it won’t drive the trim until

• the pitch servo has driven the yoke all the way to the stop (which happens quite slowly, and is due to the ground pitch not being equal to the cruise pitch), OR

• you try to resist it driving the yoke (then the trim starts moving almost immediately)

This is all normal stuff. The only way to avoid it would be to block the trim servo based on the squat switches, or (for FG aircraft) an airspeed switch.

I have never seen a GA AP installation which knows the plane is on the ground. One might examine the SR22 GFC700 one, which if done could be done only with an airspeed switch.