Why would I try to fly with SVT if I have a Flight Director? SVT could be helpful for the last 300 feet in case I don’t see the runway clearly… but isnt’t the APPROACH itself is much easier with the FD…
No? I am no expert in this, but will try this soon.
In the airline business. One side has weather depicted and the other terrain..(when the conditions are mountainous and with bad weather)
For instrument approaches it’s the minima that count legally….there is already years a workgroup ongoing in Eruope called eTOD (electronic Terrain and Obstacle Data ) for Europe…..Do the Airlines want to pay for all this (enhanced data)….NO why….as long it does not improve the Operational capability it doesn’t make sense…..is it nice to have have …YES ….is the terrain database part of the Approach minima criteria ….NO…;- 
I once had an experience that the Jepp database was half a mile off track for a VFR aerodrome…if that was used during bad weather to enhance my situational awareness….(sic)
If the needles match watch you see on the SVT I would guess OK….on the other hand it’s another thing to X-check when your already monitoring plenty of other minima parameters..
I am not an expert neither … 
I think I would assure first in VMC it’s matching…
I think I would assure first in VMC it’s matching…
The problem is that if it was matching this morning in VMC there is no guarantee that it will be matching tonight in IMC. Instrments (all instruments!) do fail from time to time and it is impossible to predict when this will happen. This is why redundancy is such a good thing (and a requirement in some cases), because the more sources of data you have, the greater the chance to detect wrong indications in time. And therefore the general rule should be to use all available instruments. Only if your scanning capability is too limited for that and the distraction would be greater than the benefit (I have seen that with beginners many times, when non-precision approaches were flown on raw data and GPS as backup and they alterntively followed the two indications resulting in very unstable approaches), turn off what is least required.
I fully agree however but at 300Ft handflying an instrument approach you may drift quickly from your GS or LOC when the needles and the SVT don’t seem to match…another cone of confusion.. but I haven’t flown one so this is just an assumption from my side…
If budget is not an constraint: a combined system like the Honeywell Smartview with enhanced vision can’t be beaten I think
I fully agree however but at 300Ft handflying an instrument approach you may drift quickly from your GS or LOC when the needles and the SVT don’t seem to match…another cone of confusion..
The normal way to fly in ILS at and beyond the minimum (single pilot case!) is to stay on instruments – ILS crosspointer or flight director usually – until reaching the minimum, looking outside for the approach lights and then alternating between ILS indicator and outside world until position and attitude can be derived from visual clues alone. In marginal CAT 1 weather this may take until the last 50 ft or so. So this “drift” that you describe will happen in any case because it is part of the procedure. Using synthetic vision displayed on the same screen as your ILS crosspointer will improve stability during the final phase of flight because you can stay focussed on your screen instead of alternating between inside and outside. Of course you must verify that the lights are really there when at minimum and of course you must flare and land visually (real vision – not synthetic…) in the end. And – most important – you must have the discipline to go around if you can’t acquire the real landing lights when reaching the minimum. I fear that a lot of pilots who have come to trust their SVT will be tempted to think “this thing worked well 99 times, why should it fail today?”
…why should it fail today?
Because it WILL – like anything in an airplane at one point.
Because it WILL – like anything in an airplane at one point.
This fall I have had my third GPS failure. Like in the other two cases, it was antenna related. Moisture getting in, freezing, whatever – it failed during the cruise. No big deal, the FMS continues to provide (B-RNAV / RNP5) positions in DME/DME mode and the minimum equipment list allows for ten more days of operation provided no procedures are flown that require GPS positioning. But it could also have failed in the same manner on someone who was attempting a “blind landing” using his synthetic vision system. With only a few seconds of time remaining for realising that something is wrong and that only an immediate go-around can save the day…
I really think that the more these synthetic vision systems find their way into GA cockpits, the more accidents we will see that are related to them. Use it properly and if will increase safety, abuse it and sooner or later someone will get hurt.
There was talk at one time of a requirement for aircraft flying GPS approaches to have 2 GPS sources. In fact the draft regulation called for the 2 sources to be identical. This came up when I was specifying the avionics fit for a new aircraft and the result was expensive. Unfortunately I dare not risk getting it wrong because it would have been even more expensive to do it later.
I do not know if this requirement still exists.
So I always leave SVT on and think it is a good additional confirmation that things are going the right way. I always fly with the FD or autopilot the advantage of which is that if hand flying you can always just hit AP and the autopilot will take over straight away. I think SVT is most useful on an NPA where it helps confirm that the runway is where you are expecting it to be before you get visual and your ROD is about right to touch down.
There was talk at one time of a requirement for aircraft flying GPS approaches to have 2 GPS sources
I haven’t heard of that one. Certainly not a requirement at present, anywhere I know of. Where did you read about this?
