Altitude Alerters

[jpower]

Hi all,
I have a question regarding altitude alerters. Does anyone still use them today in standalone form given all the fancy pants electronics in cockpits? If so, are they really spending upwards of $600-$1000 or even more on them?

I wonder, because I looked at the features of what looks to be one of the top of the line altitude alerters (see the family here), and I could build one of those for a LOT less than what they're selling for by removing just a few features that don't seem terribly important (like receiving altitude data from the transponder (and getting it from a super accurate pressure sensor instead) and audio output to a headset). Obviously, it wouldn't work in a pressurized aircraft...but is there something else I'm not seeing, like expensive certification hurdles? Is this even a device that has to be certified? Or is there a small fortune to be made by undercutting their price by half or even more?

Thanks!

 

[Captain]

If there's not a tone in the headset what would the indication be to the pilot? A light on the panel?

 

[pericynthion]

Cute the way it decodes the over-the-air transponder signal.

You can get up to a couple of hundred ft of error between the cabin ambient pressure and the static pressure, so that might be a problem with your version.

Mostly though, I think the market's just small and the development + production costs are higher than you'd think, even for a relatively simple product like this.

 

[jpower]

If there's not a tone in the headset what would the indication be to the pilot? A light on the panel?

A loud tone played directly through the cockpit, which would work for all but those who wear ANR headsets (though I don't know--maybe the tone would be loud enough to get through ANR. I've never worn one so I don't know how effective they are). Though now that I think about it, a lot of pilots are using ANR headsets these days. If a headset tone is truly a crucial feature, it wouldn't be horribly difficult to add and would probably not add more than $10-$15 to the cost. Though this would be ideally a portable unit, meaning that it would be on the glare shield, thus meaning that wires would have to run around to the headset jack...

Either way, there would definitely be a visual indication on the panel (an LCD display) showing current altitude, selected altitude, altimeter setting, any altitude deviation alerts, etc. This in addition to a sound warning, of course.

 

[jpower]

Cute the way it decodes the over-the-air transponder signal.

You can get up to a couple of hundred ft of error between the cabin ambient pressure and the static pressure, so that might be a problem with your version.

Mostly though, I think the market's just small and the development + production costs are higher than you'd think, even for a relatively simple product like this.

You're right...that altitude jump might be a problem. I saw a couple of graphs of the pressure sensor's job at getting altitude in a car and it looked very accurate. Are airplanes more poorly sealed than cars? I guess any time you open up an air vent it would disturb the pressure inside...I wonder if there's anywhere in an airplane where the pressure remains relatively constant. I'll ponder that problem.

Regarding development effort, this would mostly be a fun project on the side that might go somewhere. I'd be willing to put some money and effort into it just for the experience.

And the smallish market share is what I was worried about. I was wondering if I might be able to create my own market share by slashing the cost of these units.

 

[N801BH]

The certification process will cause you to commit suicide long before you get the second prototype built....

 

[pericynthion]

The ones linked by the OP are noncertified, portable equipment.

 

[N801BH]

The ones linked by the OP are noncertified, portable equipment.

Hmmm.. then it is for experimental planes... Digikey and a few bucks and he can be the next Garmin....

 

[jpower]

Hmmm.. then it is for experimental planes... Digikey and a few bucks and he can be the next Garmin....

Even better than that, I might think . I don't THINK I would have to get these certified for any airplane, because they're considered portable electronics. But I'll let someone more familiar with these sorts of regs say for sure.

Also, how much of a jump can you see in altitude when you pull on alt static? Is it really a few hundred feet? I've read 40 elsewhere, which is well within IFR tolerances. I'd check it out next time I'm up, but the Eaglets I fly don't have an alt static source.

 

[Piloto]

A friend of mine has a similar device (Monroy ATD-300) on his Aerostar 601P that indicates the transponder pressure altitude and traffic. He use it to insure to be on the flight level assigned, very handy gadget. It also shows the squawk code.

José

 

[denverpilot]

A friend of mine has a similar device (Monroy ATD-300) on his Aerostar 601P that indicates the transponder pressure altitude and traffic. He use it to insure to be on the flight level assigned, very handy gadget. It also shows the squawk code.

José

Doesn't it also show returns from nearby aircraft? (Thus the "far" and "near" switch?)

I love his judicious use of the 1" P-Touch black on white tape on the glareshield.

And lookie... RNAV! The real deal!

 

[wabower]

I've had an Airsport since S&F in the late 90's. For me, the price was a bargain and I've used it for every flight for more than 15 years and a few thousand hours with only one battery replacement and no other MX.

My decision to buy such a device was based on my desire for an altitude pre-select of some kind, because I had concluded that the most likely bust by ATC would be due to an altitude deviation rather than a lateral mistake. The autopilot shop said I could add the capability to my KFC 200 for about $11,000, and Jim Phillips said he would sell me the Airsport Pro for ~$600. The airsport won't move the control surfaces to capture the preselected altitude, but will remind me to punch the altitude hold button that does the same thing (now on an S-tec 30A) and I figured that if my button pushing charge is 50 cents per push, I would need to fly more than 10,000 different altitude assignments to break even.

Accordingly, my advice is to KISS and just buy one.

 

[jpower]

I've had an Airsport since S&F in the late 90's. For me, the price was a bargain and I've used it for every flight for more than 15 years and a few thousand hours with only one battery replacement and no other MX.

My decision to buy such a device was based on my desire for an altitude pre-select of some kind, because I had concluded that the most likely bust by ATC would be due to an altitude deviation rather than a lateral mistake. The autopilot shop said I could add the capability to my KFC 200 for about $11,000, and Jim Phillips said he would sell me the Airsport Pro for ~$600. The airsport won't move the control surfaces to capture the preselected altitude, but will remind me to punch the altitude hold button that does the same thing (now on an S-tec 30A) and I figured that if my button pushing charge is 50 cents per push, I would need to fly more than 10,000 different altitude assignments to break even.

Accordingly, my advice is to KISS and just buy one.

Hey, but what's the fun in that?

I'd be doing it as a sort of fun and instructional exercise that might give me something equally useful as and less expensive than an Airsport. I figure I can build it for well under $100, and who knows...if I can get the cabin pressure issue worked out, I might have something. And wouldn't you rather have paid less than $600 for the same functionality?

Only question is whether there would be a market to sell it. Perhaps there wouldn't be one, perhaps it would create its own with VFR pilots flying cross countries and pilots on IFR plans. Who knows. It's all in theory at the moment.

 

[pericynthion]

I think a GA electronics product with a much larger market to undercut would be the Blulink.

 

[Everskyward]

I think I should add altitude alerters to that thread going on about what things have spoiled you.

 

[wabower]

I think I should add altitude alerters to that thread going on about what things have spoiled you.

It's also nice to see the grey-code readout so you know for sure what center is seeing.

 

[Fearless Tower]

A loud tone played directly through the cockpit, which would work for all but those who wear ANR headsets (though I don't know--maybe the tone would be loud enough to get through ANR. I've never worn one so I don't know how effective they are).

ANR doesn't eliminate all external sounds...just makes them quieter, like any headset. I can still hear the audible terrain warnings on my Garmin handheld when using an ANR headset.

 

[COFlyBoy]

Hey, but what's the fun in that?

I'd be doing it as a sort of fun and instructional exercise that might give me something equally useful as and less expensive than an Airsport. I figure I can build it for well under $100, and who knows...if I can get the cabin pressure issue worked out, I might have something. And wouldn't you rather have paid less than $600 for the same functionality?

Only question is whether there would be a market to sell it. Perhaps there wouldn't be one, perhaps it would create its own with VFR pilots flying cross countries and pilots on IFR plans. Who knows. It's all in theory at the moment.

The cabin altitude difference from static altitude will most likely be pretty constant. Just build a way to calibrate it in the cockpit.

Before the pilot sets the alert altitude just have them set the alerter's altitude to match the altimeters altitude. Unless the plane makes some major speed changes, the delta between internal pressure and external static pressure should be pretty much a constant offset.

 

[jpower]

The cabin altitude difference from static altitude will most likely be pretty constant. Just build a way to calibrate it in the cockpit.

Before the pilot sets the alert altitude just have them set the alerter's altitude to match the altimeters altitude. Unless the plane makes some major speed changes, the delta between internal pressure and external static pressure should be pretty much a constant offset.

This is what I came to. I figured that I could incur a little more in the way development costs by prestoring some calibration data for common aircraft. I can't imagine the cabin pressure differential from one 172 or Warrior to another is too different. All you need is once around the pattern to get the numbers. For the less common aircraft, all you would need is once around the pattern to set it up and then it would store for future use. You'd be golden. I'm just shooting for 100 ft increments, because that's what the Airsport does, and realistically, the changes in speed this would see when in use won't make the measured altitude jump up or down 100 ft.

 

[dell30rb]

The cabin altitude difference from static altitude will most likely be pretty constant. Just build a way to calibrate it in the cockpit.

Before the pilot sets the alert altitude just have them set the alerter's altitude to match the altimeters altitude. Unless the plane makes some major speed changes, the delta between internal pressure and external static pressure should be pretty much a constant offset.

unfortunately the cabin altitude is going to vary with speed I believe

 

[jpower]

unfortunately the cabin altitude is going to vary with speed I believe

How much is the question.... A full ± 50-100 ft?

 

[Piloto]

Doesn't it also show returns from nearby aircraft? (Thus the "far" and "near" switch?)

I love his judicious use of the 1" P-Touch black on white tape on the glareshield.

And lookie... RNAV! The real deal!

The ATD-300 shows traffic range direction and altitude as well the host transponder alt and sqk but not altitude preselect capability. If you can not remember your assigned altitude maybe you should reconsider boating (no altitude to remember).

Hey, when you are 60+ you need all the cue cards you can post on the panel.

José

 

[Piloto]

James

You have a novel idea and I admire that. But before you get into it consider your variable and fix costs and market size. Advertising costs can be really expensive. Just check the AOPA ad rates at:http://www.aopaadvertising.org/AOPA_epilot_eflight_rates.php

I myself has no need for an altitude preselect. Keep in mind that this function is already embeded in many autopilots that will automatically level the plane at the selected altitude.

José

 

[kontiki]

It's great to have a passion. I think about the same sorts of things a lot.

I keep asking myself, would I bring something truly unique and novel to the table? Is there really any need for another "me too" mousetrap?

Building for a regulated industry can involve a lot of headaches.
How many lawyers (and lawsuits) would it take before all the joy is sucked out?

I decided that if I ever did anything, ground test and troubleshooting gear is a far less risky market and there is plenty of opportunity for inovation.

 

[EdFred]

Just find a woman pilot that thinks she knows how to fly. She'll let you know when your altitude is off, and your course is off, and your mixture is wrong, and....

However Wayne's certified upgrade would be cheaper and cause less headaches even if you had to replace it every year.

 

[Skip Miller]

ANR doesn't eliminate all external sounds...just makes them quieter, like any headset. I can still hear the audible terrain warnings on my Garmin handheld when using an ANR headset.

Also, ANR attenuates lower frequency sound more than it does higher frequency sound. This is to remove the engine drone noise yet allow other sounds to get through. So all you need to do is make the cockpit audible alarm high pitched. Kinda like the stall horn, except don't make the two sound alike!

-Skip

 

[jpower]

It's great to have a passion. I think about the same sorts of things a lot.

I keep asking myself, would I bring something truly unique and novel to the table? Is there really any need for another "me too" mousetrap?

Building for a regulated industry can involve a lot of headaches.
How many lawyers (and lawsuits) would it take before all the joy is sucked out?

I decided that if I ever did anything, ground test and troubleshooting gear is a far less risky market and there is plenty of opportunity for inovation.

Is this really a regulated product? I highly doubt it would have to be certified. I could bring my cell phone with google maps on it as a rudimentary GPS backup without certifying it. Why couldn't someone bring something like this? I would drop the idea like a hot potato if I had to certify anything, because that's like stabbing yourself in the face. Twice.

Just find a woman pilot that thinks she knows how to fly. She'll let you know when your altitude is off, and your course is off, and your mixture is wrong, and....

However Wayne's certified upgrade would be cheaper and cause less headaches even if you had to replace it every year.

The $11,000 certified upgrade? Cheaper than a box that's less than $300 that you don't have to replace ever, even if you buy a new airplane? One that works in any airplane you fly, whether it's yours, a rental, or a friend's? Sure, it won't level the airplane for you. But I'd rather save over $10,700 and buy, say, 375 hours of gas.

 

[pericynthion]

Cheaper than a wife. 3F rule.

 

[wabower]

After I bought the Airsport, I found it to be an incredibly valuable device and talked to Jim at length about product development, marketing and other stuff. He has since sold the company to another nice guy (in Arkansas) but it was clear from talking to him that the market size for these products is miniscule, and the cost of booth space at OSH and other shows has increased to the point that many of them simply can't afford to attend the events that were once their primary source of sales.

Insofar as such a business is concerned, as an investment banker/startup guy I wouldn't touch it with a stick. YMMV

Hey, but what's the fun in that?

I'd be doing it as a sort of fun and instructional exercise that might give me something equally useful as and less expensive than an Airsport. I figure I can build it for well under $100, and who knows...if I can get the cabin pressure issue worked out, I might have something. And wouldn't you rather have paid less than $600 for the same functionality?

Only question is whether there would be a market to sell it. Perhaps there wouldn't be one, perhaps it would create its own with VFR pilots flying cross countries and pilots on IFR plans. Who knows. It's all in theory at the moment.

 

[EdFred]

The $11,000 certified upgrade? Cheaper than a box that's less than $300 that you don't have to replace ever, even if you buy a new airplane? One that works in any airplane you fly, whether it's yours, a rental, or a friend's? Sure, it won't level the airplane for you. But I'd rather save over $10,700 and buy, say, 375 hours of gas.

Cheaper than a wife. 3F rule.

This .

 

[jpower]

Insofar as such a business is concerned, as an investment banker/startup guy I wouldn't touch it with a stick. YMMV

If it weren't so inexpensive to get the parts, I wouldn't touch it either. I'm not looking for outside investment and am fully aware that I wouldn't get any even if I looked for it. This is first and foremost an interesting project, and second something that others may have an interest in acquiring.

After I bought the Airsport, I found it to be an incredibly valuable device and talked to Jim at length about product development, marketing and other stuff. He has since sold the company to another nice guy (in Arkansas) but it was clear from talking to him that the market size for these products is miniscule, and the cost of booth space at OSH and other shows has increased to the point that many of them simply can't afford to attend the events that were once their primary source of sales.

If this is such a fantastic device, do you have an idea as to why exactly there's such a small market for it? Is it because of the cost of these units? Is it that the market is saturated?

 

[jpower]

This .

Gotcha. Understood.

 

[alfadog]

This is pre-"digital cockpit" technology. Many folks that would buy this are in glass panels now. Not all for sure but not sure that enough of those that are not in glass would want to bother with this type of gadget. And if your device is not reading the same as either the altimeter or the transponder then it is of questionable value.

 

[pericynthion]

If you really want to minimize costs, build an earphone-jack smartphone dongle like this but with your pressure sensor instead of a mag stripe reader.

 

[alfadog]

Here is even a better idea. Bluetooth WAAS GPS. Smartphone connected to headset. App. Done.

 

[jpower]

Here is even a better idea. Bluetooth WAAS GPS. Smartphone connected to headset. App. Done.

How do you mean? What does the Bluetooth communicate with? Smartphone connected via Bluetooth with headset? What would it play through the headset? I'm not familiar with WAAS GPS operation, other than that it makes GPS much more accurate. What would this device do?

 

[alfadog]

How do you mean? What does the Bluetooth communicate with? Smartphone connected via Bluetooth with headset? What would it play through the headset? I'm not familiar with WAAS GPS operation, other than that it makes GPS much more accurate. What would this device do?

WAAS GPS picks up accurate altitude information. Transmits it continuously to smartphone by Bluetooth (NMEA format?). Smartphone app does anything you want with that altitude info, alarms, whatever. Smartphone is connected to headset. Many newer headsets have phone jack. Bada bing.

edit: see also this post:

http://www.pilotsofamerica.com/forum/showpost.php?p=875938&postcount=17#post875692

edit 2: there are much cheaper models without the data logging function that I was mainly interested in.

 

[jpower]

WAAS GPS picks up accurate altitude information. Transmits it continuously to smartphone by Bluetooth (NMEA format?). Smartphone app does anything you want with that altitude info, alarms, whatever. Smartphone is connected to headset. Many newer headsets have phone jack. Bada bing.

edit: see also this post:

http://www.pilotsofamerica.com/forum/showpost.php?p=875938&postcount=17#post875692

edit 2: there are much cheaper models without the data logging function that I was mainly interested in.

Gotcha. But would the WAAS GPS have any value in altitude reporting except for tracking? Altitude measured by GPS is different than altitude measured by an aircraft altimeter.

 

[alfadog]

Gotcha. But would the WAAS GPS have any value in altitude reporting except for tracking? Altitude measured by GPS is different than altitude measured by an aircraft altimeter.

WAAS altitude is the most accurate altitude you can get in GA aircraft. It is what LPV GPS approaches are based on. It may differ from the altimeter but that would be the fault of the altimeter.

 

[wabower]

You might start by polling various pilot forums to determine the
percentage of participants who own them. I'd guess it will be very low. Irrespective of value and contribution to safety, anything that's not free will be highly scrutinized by airplane owners.

The reason it was beneficial to me was that it provided a high percentage of the functionality I wanted at a tiny fraction of the cost. I was flying somewhat complicated airplanes on many trips each year, with a significant portion under IFR rules and/or conditions. None of our planes had altitude pre-select function on the autopilots, but all had altitude hold. So all I needed was something to remind me to push the button, and an easy way to dial in the assigned altitude and to be alerted if the airplane diverted therefrom. So it was a no-brainer for me, but obviously not deemed essential by a high percentage of pilots. I still use the unit, it's now in the radio stack in the panel of the 180, but neither affixed or "installed" in the airplane.

If it weren't so inexpensive to get the parts, I wouldn't touch it either. I'm not looking for outside investment and am fully aware that I wouldn't get any even if I looked for it. This is first and foremost an interesting project, and second something that others may have an interest in acquiring.



If this is such a fantastic device, do you have an idea as to why exactly there's such a small market for it? Is it because of the cost of these units? Is it that the market is saturated?