Sunday, March 27, 2011


Every time you start work at a new company, you have to learn their SOPs--standard operating procedures. In a two-crew environment. Most of that is not so much what you do but what you say while you are doing it. There is a very specific vocabulary and grammar and specific phraseology for each situation you might encounter. This is intended to be absolutely standardized across the company, but is not standardized between companies. That would be impossible to completely standardize because of differences in aircraft and operations, but it could be largely so, saving work not only for pilots, but for the management who have to write the manuals tells us exactly what to say.

Let's say an engine fails. The first pilot to notice it, probably the flying pilot says something like ...

"Confirm number one failed."

"Engine failure, left engine."

"Left engine failed. Confirm."

The other pilot confirms the failure with language that probably echoes the wording of the first call, then they launch into the memory items of the engine failure checklist. Typically, in a propeller-driven aircraft, the steps are to feather the correct propeller, shut off the fuel for the failed engine in a couple of places and finish securing it from the written checklist. But because shutting down the wrong engine in an emergency is a highly reliable way of killing yourself, there's usually a whole litany of confirming before anything gets turned off.

The litany above might continue ...

FP: secure left engine

NFP: left throttle, confirm

FP: Confirmed. Close.

NFP: Left propeller, confirm.

FP: Confirmed. Feather.

NFP: Left fuel shutoff, confirm.

FP: Confirm. Close.

And so on. Somewhere in here is a tipping point where the procedure becomes so unwieldy that either it distracts the pilots from flying a seriously underpowered and lopsided airplane in an emergency situation OR the captain gets fed up with it and just shuts the damned engine down as she would have single pilot, thereby bypassing all the safety the procedure was designed to provide. Both are real risks. On the groundschool course that I recently had the privilege to attend free of charge with no obligation, I had the opportunity to witness the conception of a monster as one of the instructors noticed that an SOP involving selecting bleed air off in response to a duct overheat light did not have the identify/confirm step in it. I think I managed to avoid screaming "no! no!" (or maybe that's why they didn't invite me to continue with the programme) but I thought it. It's just bleed air. If the wrong one is selected off, an SOP such as "oops, other left" or "why don't you turn them both off until you get a chance to see which shoe the 'L' is written on?" isn't going to kill you. The management pilot concerned might argue that having a full on confirmation protocol won't kill me either, but it's sad when your SOPs aren't sleek and elegant.

You end up with something like this.


Tina Marie said...

There have been some classic accidents related to shutting down the wrong engine. I remember hearing about this one as a student skydiver:

The pilot had 4300 hours, and he still managed to feather the wrong engine.

In that case, it barely mattered, because his tanks were full of water and he'd have lost the other engine in short order, but still.

I don't think it's true anymore, but when I was jumping, more skydivers died every year in plane crashes then they did from skydiving accidents. So people sat around and discussed the plane crashes at length - many of those discussions came in really handy when I finally learned to fly.

majroj said...

Ironically, on that skydiver track, if you look at the stats, probably a higher percentage of skydivers (wearing parachutes and purportedly trained), as a class, died in crashes, versus us non-certified and non-parachute wearing commercial pax. (I know why, but it's darkly humorous if you don't).

Gee, but that tenth of second used to cross confirm each and every step might save the entire plane!
(spare me).......

Devil in the Drain said...

Non-pilot here asking about "feather the propeller". Are you making that propeller's blades more, um, parallel to the leading edge of the wing? Is this so that when you try to restart the engine, that propeller is as easy as possible to turn? Or are you, maybe, turning the blades to be more parallel to the long axis, so the dead propeller offers less wind resistance?

Aviatrix said...

The latter, Devil in the Drain. Well-reasoned.

Devil In The Drain said...

So, do you ever try to restart an engine in flight, or do you just land on what you've got?

Aviatrix said...

You do attempt in-flight restarts sometimes. It depends on the specific problem, and there's a separate, non-memory checklist for the inflight restart. On the Screaming Whippet the squat switch changes the the behaviour of some parts of the start sequence, for example activating an unfeathering pump and disabling the starter motor itself, as windmilling should provide sufficient turning force.

Aaron said...

Catching up on posts...

Captain Tommy is my new hero!! He's going on my FB right away...