Differences between HDX and Classic worth the cost?

[Marc_J._Zeitlin]

Valid point - I've found ice in my RV on 3 occasions in just over 700 hours - never by choice. Your concern about autotrim in an ice situation is valid, but suggesting that we never use autotrim in IMC because of the possibility of an out-of-trim airplane being handed back to the pilot is simply not valid.

In your opinion. You're welcome to disagree, but I don't see how you can just declare my opinion "invalid".

First, the autotrim is such a useful feature in IMC flight, and so workload-reducing in a single-pilot IFR cockpit, that the benefits would be hard to overstate and most certainly outweigh the drawbacks.

I agree that autotrim is nice. But I spend about 0.001% of my flight time adjusting trim when flying IFR/IMC (or VFR/VMC, for that matter). I trim for climb, then trim for cruise, then trim for descent, then trim for approach speed, then trim for the missed approach climb (if necessary). That's five trim events in a flight, and each one takes about 2 - 5 seconds. I'd hardly call the time savings a huge benefit. To me, the increased awareness of the aircraft's trim state by performing the trimming myself more than offsets the minuscule amount of time it takes to trim. And in fact, if the plane's only a bit out of trim when the system asks me to trim up/down/whatever, it's perfectly happy to sit there for however long it takes me to finish the other things I was doing (writing clearances or whatever) before it annunciates the need for a trim change in the audio stream.

I'd be interested to hear why you believe that the autotrim is such a huge workload reducer. The A/P is most CERTAINLY a huge workload reducer in a single pilot IMC environment - that I agree with 100%. But the autotrim? Not so much.

Second, if a pilot is so blissfully unaware of their situation while flying in an icing environment that A) they do not notice and B) don't do something immediately about it while C) disconnecting the entire autopilot as well as the autotrim, then I posit that this pilot is so clueless that they would be unable to safely extract themselves from that situation and land the airplane, in which case it's already a lost cause, and through no fault of the autotrim.

Pretty harsh. The Colgan crew - a highly trained set of ATP pilots, were unable to do so, but MIGHT have been able to recover had they been more aware, due to trim requests over time, that their airplane was becoming unflyable slowly, rather than just being hit with an unflyable aircraft when the A/P said "here - it's yours now".

I'd at least like to give the pilots the chance of an earlier and simpler recovery.

Thats my opinion only, worth what you paid for it. Don't mind me, I'm just all old and cranky and stuff.

You and me both...

 

[RV8JD]

Pretty harsh. The Colgan crew - a highly trained set of ATP pilots, were unable to do so, but MIGHT have been able to recover had they been more aware, due to trim requests over time, that their airplane was becoming unflyable slowly, rather than just being hit with an unflyable aircraft when the A/P said "here - it's yours now".

The Colgan crew had no business in the cockpit of a C-172, much less the cockpit of the Dash 8 Q400.

NTSB's Probable Cause:

https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR1001.pdf

"3.2 Probable Cause
The National Transportation Safety Board determines that the probable cause of this accident was the captain’s inappropriate response to the activation of the stick shaker, which led to an aerodynamic stall from which the airplane did not recover. Contributing to the accident were (1) the flight crew’s failure to monitor airspeed in relation to the rising position of the low- speed cue, (2) the flight crew’s failure to adhere to sterile cockpit procedures, (3) the captain’s failure to effectively manage the flight, and (4) Colgan Air’s inadequate procedures for airspeed selection and management during approaches in icing conditions."

Take a look at Section 3.1, "Findings", for a litany of the crew's failings.

 

[Marc_J._Zeitlin]

The Colgan crew had no business in the cockpit of a C-172, much less the cockpit of the Dash 8 Q400.

Again, pretty harsh. They screwed up, obviously, but maybe with an earlier warning that something was going on, they wouldn't have had to react in an emergency situation, but in an earlier, developing situation.

Contributing to the accident were (1) the flight crew’s failure to monitor airspeed in relation to the rising position of the low- speed cue

Isn't this an argument for NOT having the system wait until they're actually stalling, or on the edge of, before warning the pilot that some aerodynamic situation is changing and that action is required?

(2) the flight crew’s failure to adhere to sterile cockpit procedures, (3) the captain’s failure to effectively manage the flight, and (4) Colgan Air’s inadequate procedures for airspeed selection and management during approaches in icing conditions."

I don't argue that the crew made a lot of mistakes, but these WERE highly trained ATP's. So imagine the lesser capabilities of the rest of us, who are NOT so highly trained, and would need better and earlier feedback to know what the right response was. I'm just saying that we're all human beings who screw up, and I'm trying to minimize the potential for those screwups by warning early and often. The autotrim prevents the early/often warnings, and just dumps the A/P disconnect in the pilot's lap.

It's fairly obvious that I'm not going to convince you, and since you've not supplied any information indicating just how much of a workload reducer the autotrim is, you're not going to convince me either. Our positions are relatively clear to others, and everyone can make up their own minds how they want to proceed with the autotrim function.

I appreciate the discussion, however.

 

[Raymo]

Highly trained does not equal highly capable, which was the case in that accident and many others. To say auto-trim poses some kind of risk with that kind of comparison is apples/oranges.

 

[airguy]

I know some folks with PhD's that aren't qualified to pour piss out of a boot - so I wouldn't flout the "highly trained" bit too loudly. That is not, in itself, any type of qualifier.

 

[Marc_J._Zeitlin]

It's good that you guys are able to argue the merits of the case, presenting facts and data, rather than just using ad-hominem attacks.

 

[airguy]

It's good that you guys are able to argue the merits of the case, presenting facts and data, rather than just using ad-hominem attacks.

Well if you're going to blow off the NTSB report, then you're pretty much out in left field all by yourself.

 

[Marc_J._Zeitlin]

Well if you're going to blow off the NTSB report, then you're pretty much out in left field all by yourself.

I didn't blow off the NTSB report, and I'm perfectly willing to admit and accept that the pilots in the Colgan air disaster made numerous mistakes. Obviously, they could have reacted far better and saved the plane and the people in it.

My point, which apparently I did not make clearly enough, was that MOST folks won't even be as good pilots as those folks were, given the low # of hours that most people fly and the extremely limited amount of training that most people get, and so giving anyone flying in IMC conditions the most opportunity to realize that something is going south, early, and often (as a "trim" notification both on the screen and in the headset will do) will be more likely to cause a pilot to have a positive outcome than just saying: "well, they were sucky pilots, so they (and their passengers) deserved to die".

Unless you're going to state that having autotrim does NOT cause a decrease in pilot awareness, and indicate how that's the case, and also indicate just how much time is saved BY the autotrim functionality (which I previously asked for but which information has not been provided, to contradict my position that the time savings are minuscule) so that the time savings somehow counteracts the decrease in awareness and safety, I don't see what, exactly, your (and RV8JD and Raymo) position actually is, other than "I like autotrim and I don't care if it decreases safety for people who aren't as good a pilot as I am".

Explain your position, rather than attacking dead pilots.

 

[airguy]

Dude.

If you don't like the autotrim, then don't use it.

See a doctor, get some meds.

 

[RV8JD]

Unless you're going to state that having autotrim does NOT cause a decrease in pilot awareness, and indicate how that's the case, and also indicate just how much time is saved BY the autotrim functionality (which I previously asked for but which information has not been provided, to contradict my position that the time savings are minuscule) so that the time savings somehow counteracts the decrease in awareness and safety, I don't see what, exactly, your (and RV8JD and Raymo) position actually is, other than "I like autotrim and I don't care if it decreases safety for people who aren't as good a pilot as I am".

Whew! That is the longest sentence I've seen in awhile!

Again you are incorrect. If you reread my post, you'll see that I did not voice any opinion about auto trim because it's a personal preference, IMO, and those just end up in pi$$ing contests, as it has here.

My post quoting the NTSB's report only pointed out that your portrayal of the Colgan crew's performance was not correct based on the NTSB's official findings of the accident.

 

[lancair360]

Point of fact about the Colgan accident, which I've studied and actually recreated in the sim as a Q400 instructor, even after the aircraft went inveterted in was recoverable. There were systemic issues with the training program that were in play with this accident as well.

And when I say recoverable I don't mean some Bob Hoover type skills, I mean literally let go of the controls and the airplane would have been flying again.

 

[Grizzly]

I observe your words and I conclude that the day I will install the autotrim I will set up a visual indication of the position of the trims on the Skyview display. It will cost me two potentiometers and two analog inputs in the system with an alarm indication on the high and low limits.

 

[Raymo]

I observe your words and I conclude that the day I will install the autotrim I will set up a visual indication of the position of the trims on the Skyview display. It will cost me two potentiometers and two analog inputs in the system with an alarm indication on the high and low limits.

The Ray Allen trim servos have that ability built-in. Having a manual over-ride to disable and reverse trim is also a good idea. The AP Button panel has a 3 second limit and will disable trim if held for more time but 3 seconds is too long, IMO - at least for my plane.

 

[airguy]

I observe your words and I conclude that the day I will install the autotrim I will set up a visual indication of the position of the trims on the Skyview display. It will cost me two potentiometers and two analog inputs in the system with an alarm indication on the high and low limits.

Yes on both - and a way to isolate trim power as well - those are all good points.