Tom-D
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Tom-D
Hopefully it will be as good as the street maps. Bigger sceens, bigger is better, right?
Hand held GPS
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Hopefully it will be as good as the street maps. Bigger sceens, bigger is better, right?
John Collins
En-Route
Quote:
Originally Posted by Cap'n Jack
Any idea why the hand-held is more accurate besides perhaps having WAAS?
It will read more satellites, than many of the early GPS panel mounts. The assertion that a hand held is more accurate is not true. The panel mount monitors either RAIM with FDE or WAAS and continuously calculates the integrity of the signal and alarms if limits for the phase of navigation are exceeded. In the case of a WAAS panel mount GPS, the time to alert is 6 seconds while on an approach.
The math to generate a position should work out the same in both units given equal reception of satellites.
True, then why not allow them to be used? Not Necessarily, a hand held does not exclude bad ranging signals and the accuracy calculation is not the same and there is no integrity calculation. Also, it is not a given that both units are using equal reception of satellites.
The ease-of use and screen visibility will hopefully continue to improve even for certified units.
Hopefully it will be as good as the street maps. Bigger sceens, bigger is better, right?
Originally Posted by Cap'n Jack
Any idea why the hand-held is more accurate besides perhaps having WAAS?
It will read more satellites, than many of the early GPS panel mounts. The assertion that a hand held is more accurate is not true. The panel mount monitors either RAIM with FDE or WAAS and continuously calculates the integrity of the signal and alarms if limits for the phase of navigation are exceeded. In the case of a WAAS panel mount GPS, the time to alert is 6 seconds while on an approach.
The math to generate a position should work out the same in both units given equal reception of satellites.
True, then why not allow them to be used? Not Necessarily, a hand held does not exclude bad ranging signals and the accuracy calculation is not the same and there is no integrity calculation. Also, it is not a given that both units are using equal reception of satellites.
The ease-of use and screen visibility will hopefully continue to improve even for certified units.
Hopefully it will be as good as the street maps. Bigger sceens, bigger is better, right?
rottydaddy
En-Route
Don't know enough about 'em... I just didn't get the assertion (?)that they could be safe for non-commercial flights but not for commercial flights.
OtisAir
Line Up and Wait
The newer portables definitely provide enough visual cues to enable more situational awareness than many of the older systems. It's not just having a course and track from your next waypoint. It's the descent boxes, the terrain obstruction clearances, the tops & lightning, etc...
Is it the antenna that's certified on permanent installs or the entire unit (realistically)?
Is it the antenna that's certified on permanent installs or the entire unit (realistically)?
John Collins
En-Route
The entire system including the antenna and the GPS navigator must meet the requirements of TSO C146a and the installation as well as the other details must meet the requirements of AC 23-138a or equivalent (66 pages long). For a TSO-C146a WAAS GPS (9 pages long), it refers to a detailed technical specification that it must meet that is found in RTCA document DO-229C, some 564 pages long.
A portable hand held is not required to meet any TSO requirements. It is equivalent to a comparison between first grade arithmetic and advanced differential equations at the college level. You can guess which is which.
Tom-D
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Tom-D
I don't belive that, simply because the hand held is as accurate as the panel mounted units. using the same system.
It's basically a calculator, the size has nothing to do with the accuracy.
Last edited:
wsuffa
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The question was not about the standards, it was about whether a portable GPS, which might NOT meet the standards, is acceptable for IFR. And if so, what standards should apply.
Standards are set after the basic requirements are established. If portable GPS were ever allowed, I'd expect an entirely different standard and FAA requirement.
BTW, some of the other avionics - panel mount stuff - is not required to meet TSO for Part 91....
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Bob Noel
The fundamental questions wrt to any nav systems are:
1) Accuracy - How accurate is it? how accurate does it need to be?
2) Availability - how often does it crap out?
3) Integrity - how does the pilot know the accuracy isn't good enough?
4) Continunity - how often does the monitoring of the system crap out?
(ok, I may have mixed up "availability" and "continuity", but I think the point is made)
Since a panel-mounted GPS receiver and a handhelf GPS receiver are performing the same basic functionality wrt navigation using the same basic characteristics of GPS, I would expect the standards for accuracy, availability, integrity, and continuity to be basically the same.
1) Accuracy - How accurate is it? how accurate does it need to be?
2) Availability - how often does it crap out?
3) Integrity - how does the pilot know the accuracy isn't good enough?
4) Continunity - how often does the monitoring of the system crap out?
(ok, I may have mixed up "availability" and "continuity", but I think the point is made)
Since a panel-mounted GPS receiver and a handhelf GPS receiver are performing the same basic functionality wrt navigation using the same basic characteristics of GPS, I would expect the standards for accuracy, availability, integrity, and continuity to be basically the same.
gismo
Touchdown! Greaser!
There are aspects of a handheld that don't apply to panel mounts, primarily the antenna location, lack of annunciators, and power source.
flyingcheesehead
Touchdown! Greaser!
I took the question as being "Should a standard be developed to allow portable GPS to be used for IFR?" I don't think anyone believes that there shouldn't be any standard at all, but the latest handhelds are pretty impressive compared to early IFR-approved panel mounts, and with some additional work could probably be made just as safe.
Anthony
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Anthony
Totally agree. Guys are flying IFR using the newer "handhelds" like the 696hardwired into the plane's electrical system. They have other means to technically fly IFR but in reality are using the GPS to fly the plane.
wsuffa
Touchdown! Greaser!
A TSO usually specifies a LOT more than just those factors. So while accuracy, integrity, etc, might have similar standards, panel mounting, displays, annunciators, etc might not.
Agree
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Bob Noel
>There are aspects of a handheld that don't apply to panel mounts,
>primarily the antenna location, lack of annunciators, and power source.
All of those are considerations for both handhelds and panel mounts.
>primarily the antenna location, lack of annunciators, and power source.
All of those are considerations for both handhelds and panel mounts.
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Bob Noel
yep - I know TSO's usually specify a LOT of stuff, sometimes way beyond what
they really need to specify. I maintain that the *basic* standards for displays,
annunciators, etc would have same fundamental basis. Displays need to be
readable, power needs to be appropriate (e.g., last long enough for the intended
purpose without compromising other systems), etc
they really need to specify. I maintain that the *basic* standards for displays,
annunciators, etc would have same fundamental basis. Displays need to be
readable, power needs to be appropriate (e.g., last long enough for the intended
purpose without compromising other systems), etc