Trim technique
A brief discussion came up and quickly died down in the Lion Air thread, which I thought might be interesting to continue, but don't want to derail that thread. It was centered mostly around whether to fly with the trim as primary pitch control, or keep to using the elevator for maneuvering and taking the stick forces out later with trim. As with many internet discussions, both sides' succinct statements were misunderstood and overextended into meanings/situations probably not intended. Overall my position is that it's a nuanced issue with room for application of both philosophies in different situations; and that any hard-line blanket policy is likely to miss situations where it would be ill-applied.
The basic premise of trim, of course, is that it's there to remove long-term stick forces that are already developed. And in many cases where someone is new and/or nervous, they tend to overtrim, back and forth, greatly increasing their workload and destabilizing the airplane. I saw it in myself as a light plane student, saw it in my own light plane students as an instructor, and saw it in myself as a new jet FO in the CRJ.
Especially given that the CRJ's stick forces are way higher than almost everything I'd flown before, the importance of trim naturally impressed itself upon me. Since it was prevalent in my brain, any time I was task saturated and some light turbulence started, I'd immediately trim against it. But since there was no long term state change (this trim setting has held a neutral stick force at this speed, thrust, and flap setting for the last 20 seconds, hello McFly! So why the change?) it only leads to having to correct back the other way, which I do but by the time I do it I've lost some speed and gained some altitude, all of which needs to be corrected at the same time as well; and as I PIO my way through all that, whatever little task capacity I started with, has shrunk to nothing.
Things got a lot better once I realized this problem, and forced myself to not trim against every stick input. Anytime I'm in bumps I fly only with the stick for at least a few seconds, and then ask myself if the numbers of up and down inputs have been about the same, or there's a preponderance of one or the other; and only in the second case would I retrim. After that, wait a few more seconds, etc.
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However, there still are some cases for which I actively fly the airplane with the trim. What they all have in common is that they're phase transitions where I know about the long-term trim change ahead of time, so why not A) lead with it instead of B) doing the thrust and elevator first, letting a strong stick force develop, and then fixing it with the trim? Doing B can lead to some big stick forces (especially since it's a high engine jet with a reverse thrust-pitch couple, and with artificial feel that makes it hard to make delicate changes around neutral) that can lead to some pitch roughness as I fix it. These situations are:
- Beginning a climb or descent from level. I know that the thrust change is gonna try to do the opposite thing with the nose relative to what I intend, so (in beginning a climb) a long-ish blip of nose-up trim as I increase thrust kills the nose-down tendency before it even starts, starts the nose going up smoothly, and then I manage slight deviations with the elevator until it settles into the new attitude, whereupon I do some final clean-up trimming.
- Accelerating before/after flap retraction, and after 10,000 feet. At 10,000, a nice long press of nose down trim starts the nose down very smoothly, it initially settles right around a 1000 fpm climb rate, and then a little blip every few seconds keeps it at that rate as I accelerate until I reach the final climb speed. On a smooth day, not one elevator input has been made! This is by far the smoothest way I can fly this phase, and a hardline elevator-then-trim philosophy would have me making pointless elevator inputs that I would have to release later when making the trim inputs that I'm making anyway!
All this reminds me of my last airplane the King Air, (normal thrust-pitch couple) where I got to a point where in levelling off from a descent, I'd start a power increase (nice and early and slow), finish with a blip of nose-down trim right as I came level at my target altitude, and not once make an input to the elevator. The smoothness, efficiency, and... "one-ness," if I may, gave me such a pleasure...