Peter wrote:
Sure, but there are radios with an ILSWould you really rely on a handheld NAV radio for an IAP down to minimums, assuming you also have some sort of GPS (be it a tablet or an aviation receiver)? With any GPS you can construct your own overlay to an approach if needed.
I have my instrument students fly an ILS to LOC-only minima with nothing but their (!) handheld device and a simulated total electrical failure on the aircraft. At least in a slow SEP this works surprisingly well.
The question is whether it is wise flying an airplane which has this single point of failure named the vaccum pump without a proper backup. It is not that expensive to have either an el horizon or in today’s day and age even a backup EFIS. Both can safe your lifes in a situation like in the movie linked by bosco.
Personally I have the Aspen PFD plus the vaccum driven horizon. I also carry a Dynon D1 with me and would definitly have it on in an IFR in IMC flight. That would give 3 sources of primary attitude reference totally independent of each other. Two of which, the D1 and the Aspen have backup batteries and their own light source. You don’t have to loose your vaccum pump to get into a nasty situation, it can also be a failure of your lights at night for instance.
Partial panel is something which is important to learn but with today’s backup systems available, it should in fact be a thing of the past to loose airplanes because of this kind of failure. History shows that it is very difficult to maintain control of any airplane without a proper attitude reference system available in full IMC and does require constant training to be able to accomplish in a real life failure situation. The case of the Bonanza shows this brutally. Another case where the final straw to disaster was the loss of instruments was the case of Swissair 111, who lost all primary and 2ndary instruments due to a fire on board while trying to land at Halifax. At the very end, they were left only with tiny backup instruments they could not see anymore due to smoke. Following the accident, the airline installed EFIS backup instruments, which are much easier visible due to high luminance.
Would you really rely on a handheld NAV radio for an IAP down to minimums
Definitely. This would be an emergency, and in an emergency you nearly always go for an ILS.
mh wrote:
The pendulum will enable you to prevent this.
Sorry, but I’m starting to think that you are pulling my leg. A pendulum can only tell you the same thing that the ball does, i.e. if you are in coordinated flight or not.
You say “with the ball centered, the plane just turns when the wing drops”. It doesn’t “just turn”. Most, if not all, aircraft are slightly unstable in roll. If you have no way of determining the roll attitude, the wing is very likely to continue to drop and then you’ll have the spiral dive.
The only way you could conceivably maintain control without either visual references or gyro instruments is if you have an indication of heading or track which is both stable and very fast reacting. Then you could use the rate of change of heading/track to get a rough feeling for your roll attitude.
https://en.wikipedia.org/wiki/Foucault_pendulum
Not a gravity indicator but a moving pendulum. Still don’t think it would be of any value.
That video is very well made and poignant.
On partial panel: if I loose my HSI, even with the lag, I would prefer using the GPS rather than the compass, especially in turbulent IMC. My GPS displays bearing to waypoint and track, so I just need to make the two equal.
If I loose my AI, the previous owner had installed a backup AI with a battery and that’s very useful. With the GTX345 I now have SynViz on the iPad as well, although I need to train myself to use it and see how comfortable I am to have it as a confirmation instrument – it may actually be a dangerous distraction.
Airborne_Again wrote:
Sorry, but I’m starting to think that you are pulling my leg. A pendulum can only tell you the same thing that the ball does, i.e. if you are in coordinated flight or not.
If you are just letting a pendulum hang, you are right. However, a swinging pendulum very much indicates movement. As the Foucault pendulum indicates the earths rotation, it indicates the turn of an aircraft.
Of course ANY gyro or cellphone / tablet can and will be more accurate and easier to handle, but given the situation of losing all that, the pendulum seems to be at least an option to extend one’s possibilities. (Noone suggests to fly an ILS solely with a pendulum…)
Airborne_Again wrote:
You say “with the ball centered, the plane just turns when the wing drops”. It doesn’t “just turn”. Most, if not all, aircraft are slightly unstable in roll. If you have no way of determining the roll attitude, the wing is very likely to continue to drop and then you’ll have the spiral dive.
If the ball is centred, the plane will only fly straight with level wings (in good approximation). Hence, if the ball is centred, every bank angle will lead to a turn around the vertical axis. And this is, what the swinging pendulum is indicating. If you let it swing fore-aft, you will notice the turn of the aircraft around the pendulum. So a front-left to aft-right movement of the pendulum is based in a right turn, which is an indication of a right bank angle, if the ball is centred.
You will not enter a spiral dive, if you keep the pendulum centred. You have to take care a bit on re-energising the pendulum.
It is a very rough method, but enough to stay alive longer than with no instuments at all.
Does anyone actually has a pendulum in the plane? Not sure if all a big joke or…
If it worked, it sure might be better than nothing in case of an EMP that kills all electronics,but:
1) I doubt the capacity of the human eye to detect small enough movements in the said pendulum (especially because they will only be noticeable after a swing I suppose)
2) Not sure how vertical movement (“pulling” or “letting loose” the pendulum) would affect things.
3) How do you fit it??
Seems to me that a toy gyroscope (the ones you wind with a rope) would be slighly more usefull less useless.
The pendulum seems as as useful as pedals in case your engine quits.
mh wrote:
You will not enter a spiral dive, if you keep the pendulum centred. You have to take care a bit on re-energising the pendulum.It is a very rough method, but enough to stay alive longer than with no instuments at all.
Ok. I agree that a Foucault pendulum in principle can be used to indicate changes in heading which would help. But I doubt that it is possible in practise to set up and observe the pendulum with any kind of precision and also that it will make any noticeable difference in survival time. Have you tried it yourself in real or simulated instrument conditions?
IMHO if you are looking for a cheap backup for an all-out emergency e.g. an all-black panel, one of these will do it
provided you are not at Vne+20% and a 60 degree roll angle and going down at -5000fpm at the point you realise something is not right 
And that takes maybe 30 seconds even in a French pop rivet covered plane like a TB20 
