PilotDAR someone should mention this to the RAF and most UK aerobatic instructors. I would still subscribe to the Aileron neutral part of PARE and not call it an old wives’ tale.
Some types if you were to recover first with pitch will result in a high rotation spin due to rudder blanking, the T67M being prone to this. Unfortunately another one was recently lost to what appears to be a spin. Am not sure how many of the original production run have been lost to high rotation spins, but perhaps 5% or more? The RAF would abandon the type at bail out altitude on a more regular basis than perhaps civilians realize. This is despite an annual instructor check for high rotation spin recovery.
I am not sure how the standard you mentioned would be possible once you have entered the stable auto rotation phase, although I can see how pronounced washout would keep the ailerons flying at the incipient stage.
Have not spun the Harvard, I believe it is discouraged, but it will carry out a falling leaf manoeuvre with aplomb, if you enjoy ironworks falling at a rate of 8,000 fpm.
If you set an altitude lower than the elevation of the airport and press VS+ALT after takeoff, the airplane will descend to that altitude at -500 ft/min
Are you sure? This seems like an extremely poor design if true. If the pilot has not commanded/specified a vertical speed then why should the AP assume one?
Because the standard descent/climb rate is +/-500, so you don’t have to specify a ROD/ROC, which is actually comfortable.
VS+ALT means: descend/climb with 500 ft/min to set altitude. You can always change the ROD/ROC by turning the VS knob on the autopilot panel.
I always have 110 KIAS set in the speed window. After TO i either press AP which will hold the pitch and roll present at the time of engagement, or i just press IAS and HDG and let it climb with 110, or (VMC or safe altitude) i press IAS+ALT to let it climb to the set altitude witn 110 KIAS, followed by NAV to intercept the GPS course
I got this which appears to confirm the automatic loading of -500fpm
Obviously I don’t think -500fpm is some sort of standard figure. It is the minimum figure which (per ICAO AFAIK) ATC expects you to achieve on a climb or a descent, and you should tell them if you will be achieving less. In reality they know GA is GA and will not be too fussy, usually… But normally I set the VS to achieve a continuous descent to the IAP platform / the IAF / whatever – because that is the smoothest way to do it and is most fuel efficient.
Flyer59’s DFC90 autopilot behaviour may however be specific to his SR22, and may be different in say Aspen installations.
I don’t think automatic loading of any negative VS is at all clever. But if this really has killed pilots, I am amazed. Are there no audio warnings of an impending uncommanded descent?
Regardless of whether 500fpm can considered “standard” or not, this is just a really bad, and dangerous, design.
The GFC700 will maintain the vertical speed currently being flow when the VS button is pressed. Then you adjust from there. So pressing VS can never cause a sudden change of pitch attitude. IAS mode works the same.
The only exception would be if you were using the flight director only, configured a negative VS but ignored the command bars and flew level anyway. Then the AP would obviously pitch down on pressing VS as in that scenario you have “pre-loaded” a given VS value, which seems to be how the Avidyne works by default?
I don’t see why it would be dangerous. I have never had any problems with it, nor did others. You press VS-ALT if you want to descend and it sets the ROD to 500. And you can always change it manually. I do not see why that would be dangerous. But I am very interested in learning, if it is.
Flyer59 wrote:
Doing that on a IMC departure (probably) killed at least 2 Cirrus pilots.
Flyer59 wrote:
I don’t see why it would be dangerous. I have never had any problems with it, nor did others. You press VS-ALT if you want to descend and it sets the ROD to 500. And you can always change it manually. I do not see why that would be dangerous. But I am very interested in learning, if it is.
Which?
I wonder if any SR22+Avidyne+DFC90 owner can confirm that it really does this?
The GFC700 will maintain the vertical speed currently being flow when the VS button is pressed
That would be fairly standard.
There are some other modes however which one can get into with weird button sequences e.g. PIT and VS=0. That isn’t quite ALT HOLD… the plane will drift up or down, slowly. The KFC225 had a bug which was at some point c. 2002 quietly fixed, whereby it would display ALT but actually it was (in effect) PIT + VS=0. Nasty!
@Flyer59, I think you described yourself at the beginning, why it could be dangerous.
If you are climbing out full power, at 1000fpm, in IMC, then how can it not be dangerous for the aircraft to pitch down towards the ground on a single button press, when you were expecting it to do nothing but maintain the current profile?
I realise this requires human error (incorrect AP programming) to happen, but the design should protect against that.
Pitch=0 is indeed not altitude hold, but it’s also fairly benign.
@ortac
sorry, I answered before you asked. You simply don’t use that mode in climb, that’s all. And there’s always a way to make things dangerous, be it an SR22 or an Airbus, you have to know the system.
If you want the aircraft to maintan the current profile you press “AP” only, that’s all. I guess most people can learn that.
Edit:
You can also select a ROD and altitude manually before you press VS+ALT. It only jumps to +/-500 fpm if it was not preselected and you press VS+ALT. Sorry forgot to mention that.
