Antonio wrote:
I also check flaps since sometimes they have been inadvertently partially extended.
Yes. I have the same thing with my P210. I adjust the heating, and my hand has brushed the flaps handle, and I didn’t notice. Had me looking all around on my last flight, and my passenger silently wondering what was the sudden increase in stress level.
Always young in spirit, especially this time of the year. Glad to see you made if safely on the ground to that airport within gliding distance!
I always thought it would be rare to have induction icing in the carburetor with wide open throttle in cruise, but obviously not so rare or perhaps not WOT or the uncontrolled heating valve made it worse?
I tend to see life as Camembert, it needs age to taste well ;-).
It wasn’t full WOT and the loose valve may have some take on it.
dejwu wrote:
you appear to be a bit elder as well
Always young in spirit, especially this time of the year. Glad to see you made if safely on the ground to that airport within gliding distance!
I always thought it would be rare to have induction icing in the carburetor with wide open throttle in cruise, but obviously not so rare or perhaps not WOT or the uncontrolled heating valve made it worse?
I would find it weird not to notice….I am always striving for efficiency and looking for causes for a decrease! But then when flying LOP above turbo critical altitude you have to be monitoring all the time anyway. Things can change a lot in one minute.
OTOH what was your aircraft type and what was your issue? Induction icing?
So, you appear to be a bit elder as well …
A carb’ed 172 and induction icing and a detached carb heat cable … unfortunate combination ;-).
dejwu wrote:
AH = Altitude HoldInteresting was my fast reaction before the EP (Envelope Protection) of the AP (AutoPilot) came into play.
Q (Question) to the once flying more VP/CS & auto-trim & no-EP: wouldn’t you recognize 10 percent power drop on your butt?
I would find it weird not to notice….I am always striving for efficiency and looking for causes for a decrease! But then when flying LOP above turbo critical altitude you have to be monitoring all the time anyway. Things can change a lot in one minute.
OTOH what was your aircraft type and what was your issue? Induction icing?
AH = Altitude Hold
Interesting was my fast reaction before the EP (Envelope Protection) of the AP (AutoPilot) came into play.
Q (Question) to the once flying more VP/CS & auto-trim & no-EP: wouldn’t you recognize 10 percent power drop on your butt?
speed starts to drop immediately due to AH
What is “AH”?
After reading this thread, I pulled the data (audio, video, track log) of my recent safety landing for review, conditions: VMC, CAVOK, M01C/M03C, cruising at altitude, autopilot on track, no auto-trim, fixed prop, me reading something else. About 2 hours in flight, RPM starts dropping from 2450 to 2200, speed starts to drop immediately due to AH, time to react was less a minute, autopilot disengage after 2 minutes, remaining power assisted glide was plenty to safely reach the next airfield. From the material I suspect everybody will recognize fast a quick 10 percent drop in performance in a fixed prop aircraft. VP/CS, auto-trim and slowly degrading performance is a different animal, but a 10 knots reduction should be recognized immediately (Btw, on IFR flights I put these little PostIt arrows at meant positions on the instruments to increase situational awareness – anybody else?).
I think we have all at some point left the flaps in the takeoff position, and I even did it with the landing gear a couple of times 
But more subtle reasons can be a rigging problem e.g. the flaps not fully up on one side, and you need only a few mm to then require a lot of aileron trim, and/or rudder trim, and lose perhaps 5kt, and the chances are that almost nobody in the maintenance business will ever find it.
Other, easier to fix, reasons can be a duff RPM gauge (on a fixed pitch prop plane), a duff fuel flow gauge, etc.
Timothy wrote:
I must say that if I suffer a loss of airspeed, I first check for ice, and then assume mountain wave. Only if there is no ice and the performance loss continues more than about 5 minutes would I start considering other things.
Sounds like a plan! I also check flaps since sometimes they have been inadvertently partially extended.
