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Questions tagged [gnss]

GNSS is a global satellite navigation system. GPS is the US GNSS.

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105 views

What's the busiest airport that's not WGS-84 compliant?

Most latitude and longitude coordinates are defined relative to the WGS-84 standard, including GPS coordinates from your receiver. However, some coordinates are specified using local datums, and ...
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Does EASA allow using a portable GPS for RNAV capability?

Assume an older IFR-certified aircraft with the classical equipment, that is two VOR/ILS receivers with plain CDIs, ADF and DME, but no GPS. It can be flown IFR, but many routes can't be used, because ...
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212 views

Can a GPS waypoint be used when filing a VFR flight plan?

This probably equally applies to IFR flight plans, but the general question is can arbitrary (unrelated to an airway or named fix) GPS coordinates be used in the route on a flight plan?
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Can jetliner pilots program departures when specific RNAV procedures do not exist?

Can commercial pilots (e.g. 737 and 737 Max) program departures into their on-board GPS navigation system for the first portion of a flight that doesn't have specific RNAV procedures?
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154 views

What are the ICAO GNSS waypoint naming conventions?

I'm curious about ICAO naming conventions regarding GNSS and RNAV waypoints. Would I be correct in assuming that all GNSS area waypoints are 5 letters, and RNAV waypoints are 6? What about waypoints ...
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102 views

Does a GPS OBS selector use magnetic or true courses?

Under GPS navigation, when we are using the OBS to tune courses. Are these courses magnetic or true?
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What's the minimum number of sensors for a hobby GPS waypoint-following UAV?

I would like to develop my own guidance, navigation and control (GN&C) flight software on a Raspberry Pi, for a small hobby fixed-wing UAV. From a physical standpoint, what is the minimum set of ...
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58 views

Compute great-circle track from longitude

The Aviation Formulary defines Clairut's formula to compute the intermediate track (bearing) for a GC based upon latitude, but any given GC (ignoring one passing through the poles), crosses a given ...
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1answer
108 views

Will the IFR Grade GPS be an requirement in the future?

This question is directly related to my other question so I have to ask it I think its obvious why I ask this if you read that question but I will repeat myself again. Station based navigation is ...
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137 views

What technologies exist to find an aircraft position after it crashed out of line of sight? [closed]

What is the best way in the manner of products to find an aircraft after it crashed out of line of sight. Are there defined standards, and what are the selection criteria?
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246 views

Is there any plan to create GPS approaches to water areas for seaplanes?

Is anyone working on differential GPS approaches for seaplanes? They are a largely ignored resource with great capabilities for certain remote places
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124 views

What does mean 'GS' in RNAV (GPS) Chart?

Hello. I have a question about 'GS' in my RNAV(GPS) Approach Chart. Usually, (Including PAPI, VASI whatever...) Normal Glide Descent Angle means 3.00 degree. but some 'GS' says 3.07, 3.04, 3.09 ...
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288 views

What is the difference between RTK GPS and GBAS?

My understanding is that real-time kinematic (RTK) is also a differential GPS technology to enhance accuracy by using a ground-based station to provide the correction data to the onboard GPS receiver. ...
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What did Fiji have to do when it incorporated GPS into its aviation system?

I'm reading the BBC's How Fiji changed the way we travel; The little Pacific island nation was the first to incorporate GPS into its aviation system – and in doing so forever changed the way we get ...
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What does “zero offset between two waypoints” mean in ICAO Doc 4444?

My question is with reference to the GNSS based separation specified in ICAO Doc 4444. Could someone explain the significance/meaning of the condition "zero offset between two waypoints" criteria? if ...
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102 views

Will a non-certified GPS source work the same in ADS-B mandated airspace?

What happens if you use a non-WAAS GPS position source in ADS-B mandated airspace? Doesn't it work the same, except for the positional accuracy?
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358 views

Is smart phone's GPS accurate enough to calculate airplane speed? [closed]

Around seven years ago, I did airplane speed measurement. I activated the GPS on my tablet and I monitored the speed, especially when the airplane touched the ground (runway). I found that the ...
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1answer
124 views

What is the difference between EPE and HUL on the Satellite Status Page of GNS systems?

For exemple on the GNS430 satellite status page you can read, in addition to the GPS receiver status : EPE (Estimated Position Error) DOP (Dilution of Precision) HUL (Horizontal Uncertainty level) ...
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What is the area coverage of a RAIM availability prediction check?

For example on GNS430 you have a RAIM availability prediction tool : one must enter a waypoint, date and time to compute RAIM availability prediction at +-15min. How big is the area around the ...
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What is a blind encoder?

As I'm studying, I found that GPS has to have 5 satellites or 4 satellites with "blind encoders" to use RAIM. What is a blind encoder and what is its purpose?
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464 views

What are the considerations for coding the GPS before engine start without external power?

Suppose I would need 10-15 minutes to fully configure my G1000 on a C172 ahead of a flight, with the flight plan, my personal view settings, etc., and prefer to do that before starting the engine. My ...
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2k views

How to navigate an aircraft without GPS? [duplicate]

In case of loss of GPS: how can an aircraft not only be navigated but navigated so precisely that it can pinpoint its destination airport ? (case in point: Finland and Norway are telling airline ...
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1answer
3k views

Is GLS (GBAS landing system) an RNAV approach?

PBN which is contrast to conventional navigation consists of RNAV and RNP. And I know that general RNAV approach of IAP has up to 4 minima such as LPV, LNAV, LNAV/VNAV, and LP. And I know that GLS ...
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Are there (ideas for) GNSS based attitude indicators?

With upcoming GNSS systems that have better accuracy than GPS, could there be an GNSS based attitude indicator? Does maybe one already exist? I could imagine having 4 sensors (front, aft, left ...
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Are NDBs and VORs dying as a navigational method?

I am new to aviation, so bear with me on this question: I have read in multiple places that the VOR/NDB navigational aids are dying out to GPS. Is this true? Are more modern aircraft being built with ...
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434 views

How do GLS avionics plot an entire accurate approach path?

I'm studying wireless navigation systems, especially GBAS. I have gone through some ICAO documents regarding GBAS. From what I have read, FAS data is included in Message Type 4. Closer examination of ...
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220 views

If a SID chart says “GPS… required”, can the plane use a different GNSS?

This US/FAA standard instrument departure says "Note: GPS or DME/DME/IRU required." If the aircraft could tune into a different GNSS like GLONASS, could the pilot still legally fly the departure ...
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1answer
714 views

Why would a Mode-C transponder report a different altitude than an altimeter/GPS?

This is related to a small single-engined plane. On a recent flight, the controller kept telling me that I was 300 ft higher than it appeared on my altimeter and GPS (which were in sync). This was ...
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1k views

How can I tell a GPS installation is acceptable for IFR use?

I am evaluating an aircraft for use under IFR. I want to know if the GPS that is installed is acceptable for use under IFR. I have access to the logbooks and documentation. I want to check: That ...
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1answer
170 views

Position update rate of GPS [closed]

GPS satellites send data at the rate of 50 bits per second. One GPS subframe is 6 seconds long. How is it possible to update one's position faster than once in 30 seconds when we require the whole ...
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1answer
183 views

How do you program circular flight plans in GPS?

In a recent Buzzfeed article about aerial surveillance, I have seen a map showing perfectly circular flight patterns. Given how precise the patterns are, I highly doubt that the aircraft were being ...
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1answer
724 views

Is a non-WAAS Garmin 530 certified for an LNAV/VNAV approach?

I may not understand all the details of what I'm asking but trying to wrap my head around it. I am aware that before WAAS, some GPS aircraft were equipped to get vertical guidance by a Barocorrected ...
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1answer
493 views

Are there any precision approaches that use only GNSS/LAAS?

Is there any airport which has a precision instrument approach using only GNSS (augmented with LAAS) for guidance?
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435 views

Does the altitude or attitude of an aircraft affect GPS accuracy?

Of course we are assuming an effective signal is being received. I live near Idaho Falls, Idaho with a field elev of 5300ft. If I shoot an approach will GPS be more or less accurate then landing at ...
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216 views

Why is there a provision of pressure setting in GPS?

Some of the GPS have a provision of setting barometric pressure (QNH/QFE). How does it work?
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11k views

In the rare event that the U.S. DOD shuts off the GPS, what's the alternative?

In the U.S., the Department of Defense along with other Federal Agencies of the Government operates & maintains the GPS. In the rarest of the events, if for any reason whatsoever, the Government ...
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What is the geoid undulation used for in aviation?

In addition of the altitude found on aerodrome information, the French AIP also mentions the value of the geoid undulation:: AIP for Lyon - Saint Exupéry (LFLL) Geoid undulation is also found in ...
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1answer
675 views

When should I start turning in this circling approach?

I've been practicing circling approaches in Homestead General Aviation Airport in Homestead, Florida (X51). I performed the RNAV (GPS) RWY 10 approach with circling minimums. My questions are: a) ...
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1answer
699 views

What are the WAAS requirements for RNAV (GPS) approaches?

Is a WAAS GPS required to fly in RNP airspace (e.g., RNAV (GPS) approaches)? Or, can you be approved to fly RNAV (GPS) approaches with, say a military EGI (embedded GPS/INS)?
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1answer
3k views

What are the lateral sensitivities of GPS approaches?

What are the lateral sensitivities of each of the WAAS and LNAV approach? Is the lateral sensitivity of WAAS the same as that of the localizer, which is 3 to 6 degrees? What about the LNAV approach?
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266 views

What is the correlation between RNP level and the CDI indication?

I got a question regarding the connection between RNP (required navigational performance) accuracy and cdi sensitivity of the HSI. According to the instrument flying handbook the standard for RNP on ...
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692 views

Can the iPad use GPS data from a Garmin aera 660?

Can the iPad use GPS data from a Garmin aera 660 portable GPS unit? I assume this would happen via Bluetooth, if it's possible. I would like the more accurate WAAS data from the Garmin for use with ...
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1answer
343 views

Why is there a GPS/RNAV waypoint co-located with a VOR?

There is an RNAV waypoint named STYCK co-located at what appears to be the exact location of the LOA VOR (coordinates match precisely as well). Why would the creation of a waypoint be necessary if IFR ...
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252 views

How can I check that the GPS receiver is sending data to the transponder?

I fly an ultralight aircraft. The GPS is a puck-type device from which the TX line runs to the mode-s transponder. The transponder does not readily show if it is receiving position data. The data is ...
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1answer
266 views

Why don't transponders send gps coordinates and other important info in addition to altitude and transponder code?

I heard that they were waiting for the patent holder's patent to expire, but just wanted to confirm.
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252 views

Should the route be changed if the GPS RAIM prediction fails?

Do i have to change the route if the GPS RAIM prediction has one or more outages along my route?
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1answer
488 views

Is a “GPS required” ILS (or other navaid-based) approach considered a “GPS approach” for alternate planning's sake when TSO-C129/196 gear is in use?

If you have TSO-C129/TSO-C196 GPS gear (vs TSO-C145/146 WAAS/SBAS gear), you either have to have a non-GPS approach at your destination, or a non-GPS approach at your alternate. If your choices are ...
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1answer
737 views

Why do Computer Navigation Fixes still exist now that GPS waypoints can be used to define tracks?

A CNF is a point that defines a navigation track for a GPS, but why is it used when you there are GPS waypoints that are created to define a track?
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763 views

How to leverage Lynx NGT-9000's integrated GPS/WAAS?

I’m inheriting an IFR capable 1964 Cherokee 235 that is not equipped with a GPS. I’m looking at installing a Lynx NGT-9000 to get ADS-B compliant and gain the traffic and weather information. Is ...
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How does Kalman filtering work in inertial navigation systems?

As far as I understood it correctly most INS-systems use a Kalman filter to compensate measurement errors. I would like to know: Does the Kalman filter compensate the errors from all the onboard ...