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Gax
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Hi!
When doing any low-level flying, I often find myself wondering what my height is, though am keenly aware of the potential error in GPS altitude and therefore am reluctant to trust the 'Height' readout at the top of the screen. To account for this, I find myself flicking between Altitude and Height at the top of the screen, subtracting the difference in my head, and then comparing that to my (theoretically more accurate) pressure altimeter.
Would it be possible to simply add a third option to that box for 'Elevation' that shows the terrain elevation for the current GPS position? Presumably you're fetching it anyway to calculate height... If it's not in demand, maybe an option to enable/disable the feature?
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Tim Dawson
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An interesting idea. As far as I'm aware you're the only person to ask for this, which means it isn't likely we would add an ELEV option to that instrument any time soon.
Have you considered flicking it to altitude then back to height? That would let you check that your GPS altitude is the same as (or near enough to) your pressure altitude, and it is, you then know you can trust the height figure.
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Gax
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Yes, that is what I currently do, but it means a lot of constant tapping and an extra equation, and when flying low level I'd rather minimise the workload and keep both hands on controls. Would also be useful for a few of the air racers out there that need to maintain a certain minimum height.
I love SD, but find that getting any sort of current or spot elevations a frequent issue.
Is it something that could maybe be considered but turned off by default?
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guille
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+xYes, that is what I currently do, but it means a lot of constant tapping and an extra equation, and when flying low level I'd rather minimise the workload and keep both hands on controls. Would also be useful for a few of the air racers out there that need to maintain a certain minimum height. I love SD, but find that getting any sort of current or spot elevations a frequent issue.Is it something that could maybe be considered but turned off by default? I agree with this request: when flying low, it is necessary to have a good precision concerning height, and getting directly the elevation of terrain would be great. Frequently I check the altitude measured by SkyDemon and by my altimeter and the differences are quite important.
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drnicolas
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+x+xYes, that is what I currently do, but it means a lot of constant tapping and an extra equation, and when flying low level I'd rather minimise the workload and keep both hands on controls. Would also be useful for a few of the air racers out there that need to maintain a certain minimum height. I love SD, but find that getting any sort of current or spot elevations a frequent issue.Is it something that could maybe be considered but turned off by default? I agree with this request: when flying low, it is necessary to have a good precision concerning height, and getting directly the elevation of terrain would be great. Frequently I check the altitude measured by SkyDemon and by my altimeter and the differences are quite important. Are you sure, that this can be achieved by a Software like SD? At first we Need a exact terrain-altitude-database with a small grid (see ckurz7000). Is that available? Second we need a good (true) altitude readout. AFAIK, plain old GPS is not a precise source for this. Is WAAS suitable for this? What about GALILEO? From the IFR Point of view all DAs für RNAV approaches are sginificantly higher than ILS and that is for LPV! Take EDVK: DA for ILS27 is 947 feet, while LOC27 is 1340ft - 400ft difference! For GPS, the LNAV MDA is 1340 (like LOC-Approach); with Support from your barometric altitude it is 1210ft - and that is temperature limited! Best GPS DA is for LPV27 with ~1100ft - even 160ft worse than ILS! I guess, the guys who made the approaches know, why GPS Needs significantly higher Minimums ! Can the barometric pressure sensor of the latest iPads (my mini 4 has one) be a solution ? I think not! It is not connected to a valid static port, it's inside the cabin. Just try what happens if you Switch to the alternate static source of your aircraft - it jumps up about 80ft or more! Okay. We are talking about VFR-sight-seeing, so this all may be tolerable
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guille
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Group: Forum Members
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+x+x+xYes, that is what I currently do, but it means a lot of constant tapping and an extra equation, and when flying low level I'd rather minimise the workload and keep both hands on controls. Would also be useful for a few of the air racers out there that need to maintain a certain minimum height. I love SD, but find that getting any sort of current or spot elevations a frequent issue.Is it something that could maybe be considered but turned off by default? I agree with this request: when flying low, it is necessary to have a good precision concerning height, and getting directly the elevation of terrain would be great. Frequently I check the altitude measured by SkyDemon and by my altimeter and the differences are quite important. Are you sure, that this can be achieved by a Software like SD? At first we Need a exact terrain-altitude-database with a small grid (see ckurz7000). Is that available? Second we need a good (true) altitude readout. AFAIK, plain old GPS is not a precise source for this. Is WAAS suitable for this? What about GALILEO? From the IFR Point of view all DAs für RNAV approaches are sginificantly higher than ILS and that is for LPV! Take EDVK: DA for ILS27 is 947 feet, while LOC27 is 1340ft - 400ft difference! For GPS, the LNAV MDA is 1340 (like LOC-Approach); with Support from your barometric altitude it is 1210ft - and that is temperature limited! Best GPS DA is for LPV27 with ~1100ft - even 160ft worse than ILS! I guess, the guys who made the approaches know, why GPS Needs significantly higher Minimums ! Can the barometric pressure sensor of the latest iPads (my mini 4 has one) be a solution ? I think not! It is not connected to a valid static port, it's inside the cabin. Just try what happens if you Switch to the alternate static source of your aircraft - it jumps up about 80ft or more! Okay. We are talking about VFR-sight-seeing, so this all may be tolerable I think SD has a good database concerning elevation. It can be clearly seen on the computer when preparing flights. And the idea is to use this database, combined with the horizontal position, that is also quite precise with the GPS included both in IPAD or ANDROID devices. The altitude of the barometric altimeter is also precise. So, if we combine the good altitude from the barometric altimeter with the good elevation from SD a simple substraction provides a quite good indication of height. Why not ? Some years ago I used a French software called NAVI that had this possibility and it was really useful. The button for time now has four indications ! and is very useful. Why not three for the altitude-height button ? But I don't know if the elevation Database is included in the Ipad and Android versions, that may be the problem perhaps.
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Gax
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"But I don't know if the elevation Database is included in the Ipad and Android versions, that may be the problem perhaps."
It would have to be, otherwise it wouldn't be able to calculate height
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alvaro
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+xAn interesting idea. As far as I'm aware you're the only person to ask for this, which means it isn't likely we would add an ELEV option to that instrument any time soon. Have you considered flicking it to altitude then back to height? That would let you check that your GPS altitude is the same as (or near enough to) your pressure altitude, and it is, you then know you can trust the height figure. Hi all. Actually that’s not such a bad idea. It would be good to know the elevation of any random waypoints you place on the map. I’ll give you an example of why I need to know in my job the terrain elevation on the map. I work as a medical helicopter pilot (hems), and they call us to pick up an injured biker near the mountain. Before I get there I need to know the elevation of where he is, because that data will affect the performance of my helicopter drastically (Cat A or Cat B take off). If you could add a column in the PLOG with the selected waypoint elevation, it would be a huge improvement for helicopter operations.
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Gax
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Hi alvaro This thread is about the current elevation shown in-flight where altitude/height is shown in the data tape at the top of the screen, rather than spot elevation of a point on a map. That said, I have previously made a separate post on a topic closer to what you're asking for that you might want to take a look at and comment on. The software does actually provide spot elevation provided: a) you're on a tablet rather than a phone, and b) there's some form of airspace above (so unlikely to show up if you're doing rescue in places like northwest Scotland etc). I unfortunately never got a chance to get back to Tim re some layout suggestions, but that might be a good place to leave some thoughts: http://forums.skydemon.aero/Topic23406.aspx
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