... only allowed in case the GPWS or any pilot calls "Terrain, terrain" - "Too low terrain" or "pull up "
Don't have the technology myself, but colleagues report its uses with a windshear warning also.
172 driver ..the aeroplane is the venerable 767-300 with CF6 engines min clean speed is above the Flap 1 limit speed of 250 knots at weights from memory of above about 175 tonnes.Hence wings must be level for final stages of flap retraction and flaps 5 to 1 takes 23 seconds thats a long time when someone wants you on a heading after retractions started. Vbr Stampe
@ Pirho
in case of severe windshear with IAS loss Airbus expects you to apply TOGA power ( T/O & go around power) and let the autopilot do the pitch work ( not necessarily a full pull up), however, sev. windshear may exceed the performance capability of the autopilot. To avoid ground contact, the pilot must be prepared to disconnect the A/P and fly manually. Follow the flight director pitch command, use full back side stick if commanded.
(autopilot likes to disengage when alpha > alpha prot.)
Peter, I also think (or hope ;-)) i will not need the "envelope protection" of the DFC90 a lot, I feel quite confident in my hand flying abilities. But it is a NICE feature that the autopilot cannot stall the airplane and that it will warn you in case you are about to lose control. You can pull the power back to idle and the A/P will lower the nose when necessary. The "Straight & Level" button which you can use anytime you lose control of the airplane in clouds is another nice feature, and it works perfectly, at least it did from all legal maneuvers I flew (In a youtube video Avidyne shows that it works from inverted too). Of course you can argue that you will never need such gimmicks - but if you see that these autopilots even cost less than similar products in the past, not much really speaks against them.
On GPSS we almost agree. While not really "necessary" becasue you can do the same thing in NAV mode - with the two autopilots I had the GPS tracking is really very precise and nice. Just yesterday I tested a 300 degree intercept, just becasue i wanted to see what it does, and it's really impressive how the DFC90 calculates the right distances, initiates the turn before the waypoint and precisely intercepts the next leg.
And I can really live without a mechanical HSI. While i like those instruments - after only 3 months I've come to love the 120 degree Arc display of the HSI with the route underneath ... YOu se the next waypoint, you knwo which way it will turn, and right nxt to it you see the distance and time for the next WP. In my opinion it doesn't get much better than that
..the aeroplane is the venerable 767-300
Venerable indeed! Haven't been on one of those in a long time....thanks for the info.
He was flying over the desert at the time and, when the plane ran out of fuel, the envelope protection feature of the autopilot caused him to descend at a shallow angle such that, when the aircraft impacted terrrain, the pilot survived although he was quite badly hurt.
You don't necessarily need envelope protection for that, or even an autopilot. Back in 1965 in the USSR, a Su-9 pilot on a training flight over a desert ran into some problems he perceived as a control failure, and ejected. Next morning, the aeroplane was found in one piece, the only damage being to the underwing fuel tanks (as the gear was obviously up). A readout of the flight data recorder showed that the aircraft landed with zero bank at about 215 knots (normal landing speed being 170).
For those who don't know what a Su-9 is, here it is:
THere's several cases like that where an airplane in perfect trim landed by itself and was not damaged heavily. Like the B-24 Bomber "Lady be Good" that landed in the Libyan desert in WWII after the crew had left the aircraft by parachute. (A terrifying and tragic story I used in my first Aviation book "Die besten Geschichten über das Fliegen" (The best Flying Storys)
and it's really impressive how the DFC90 calculates the right distances, initiates the turn before the waypoint and precisely intercepts the next leg.
If I understood your description correctly, it's not the autopilot that does it, it's the turn anticipation function of the GPS, which can be performed by any autopilot with roll steering.
It's the GPSS computer of the autopilot. The GPSS computer is not in the GPS. But of course ANY GPSS computer dies it like that, does not have to be this one
Hello!
what next, a 20 year old Citation autopilot has GPSS? Envelope protection? I had no idea!
If GPSS is what I read here ...
(Century Flight Systems webpage: "Century's GPS roll steering module makes flying with your GPS and autopilot easier than ever. GPS roll steering lets you program a complete flight plan into your GPS; and then with the push of a button the autopilot follows your flight plan turn by turn. It even anticipates the turn based on your ground speed and distance to the waypoint.
Once activated all you need to do is moniter the aircraft and leave the navigation to your Century GPSS. By reducing your navigation workload you are able to greatly improve your situational awareness and safety in both VFR and IFR conditions.")
... then yes, a 20 year old Citation can do that. It can even do smarter things like intercepting a DME arc with a given heading and compensation for the wind ... not that I ever needed that feature.
As for envelope protection: You are correct, there is no full envelope protection (which would require some kind of fly by wire steering à la Airbus anyway). But the autopilot protects the aircraft from overspeeding during climb and descent (can't do so in the cruise because there is no autothrottle) and from stalls during climb if "FLC" mode (= Fligt Level Change - called IAS hold in other systems) is engaged.
