Questions tagged [gnss]

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

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21
votes
6answers
5k views

What will happen if satellite navigation fails?

My understanding is that aircraft use GPS systems for navigation (maybe not the only way to navigate). I would like to understand what would happen if the GPS system fails. Are there any other ...
0
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1answer
41 views

Is it possible to export NMEA data from a Garmin GDL-39 to a custom Android App?

Hi I was wondering if it's possible to receive NMEA data from a Garmin GDL 39 on an Android device (preferred over Bluetooth) as I can't find any information out there on it.
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3answers
2k views

Could the GPS be used to aid the autopilot with speed?

In the AF447 incident, the autopilot system was offline due to the aircraft's pitot tubes being obstructed by ice particles. Since the physical condition of the plane in air is cold and risky, the ...
0
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1answer
73 views

What is the meaning of GPS IAP RNP that appears in Notes?

Referring to the RNAV (GPS) RWY 30 approach, what is the meaning of RNP APCH in the notes section? (Highlighted in YELLOW) Also, what are the separate DA values in parenthesis? (Highlighted with a red ...
2
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1answer
111 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 ...
13
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4answers
3k views

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 ...
3
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1answer
83 views

In RTCA DO-260B, what were the reasons GVA was added ? Is it a replacement for something?

After digging up and reading through many documents, I have a rough picture of the evolution of DO-260 versions, particularly for its ADS-B Quality Indicators. For instance, in DO-260 (Version 0) ...
4
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1answer
104 views

Why do ADS-B outages occur without simultaneous RAIM outages?

If you check the ADS-B prediction tool and the RAIM prediciton tool on SAPT.FAA.GOV you will see far more ADS-B outages. What causes ADS-B outages to occur at different times than RAIM outages? Are ...
8
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1answer
156 views

Due to the corrective calculations being ground-based, does the reliability of WAAS degrade with increases in altitude?

Since the WAAS system utilizes stations at known, fixed locations on the ground to make determinations for positional correction, is there a loss in the precision or validity of that correction with ...
5
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2answers
885 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 ...
1
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1answer
63 views

Is it possible to determine if winds were high without groundspeed, wind speed, AoA or AoS?

I have a data set that includes TAS, IAS, GPS Lat/Lon, Inertial Lat/Lon, ENU speed, inertial speeds, attitude, and accelerations. I don't need to know the exact wind speed, and I don't think that's ...
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3answers
1k views

Are helicopter pilots required to use GPS navigation?

Some helicopter crashes are caused by a disoriented pilot. This would presumably be impossible with a GPS with terrain maps. Are pilots required to use a GPS when flying a helicopter in the US?
0
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1answer
122 views

What's the difference between a Sole Means Navigation System and a Primary Means Navigation System? [closed]

For bonus points, how you define a supplemental means navigation system?
12
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3answers
9k views

Can a pilot use their GPS/FMS to fly a VOR or NDB approach?

GPS is more accurate than a VOR or NDB signal. Can we use a GPS to fly a VOR or NDB approach from the initial approach fix through the missed approach and hold? I know there are two types of ...
0
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0answers
28 views

GPS Magnetic Declination and current database [duplicate]

Can I fly with an expired GPS database if I verify the waypoints locations? or is the magnetic declination part of the database?
5
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1answer
295 views

What is GPS HIL in layman's terms?

GNSS Horizontal Integrity Limit/ Horizontal Protection Level is a measure of GNSS position error/integrity that's very important in RNP operations and RAIM, but it has an obtuse definition in aviation ...
6
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2answers
2k views

How can I keep the data on a KLN89b GPS up to date?

I'm looking at a Mooney M20C with a pretty dated panel, but it's airworthy and could be a great opportunity to build some retrac time. The KLN89b GPS is IFR Certified, but is positively ancient. ...
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0answers
137 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 ...
2
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1answer
150 views

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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12answers
31k views

Why don't all commercial aircraft transmit GPS data in real time?

It seems strange that trucks and taxis can be set up to transmit GPS data in real time but aircraft cannot. Wouldn't this be a useful function and feasible to implement?
7
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2answers
3k views

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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2answers
451 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?
3
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2answers
132 views

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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2answers
325 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 ...
2
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1answer
209 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?
21
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6answers
4k views

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 ...
3
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1answer
921 views

Is GPS considered to be a navigational facility for the purposes of Ops Spec C055?

For 14 CFR 119 certificate holders, Alternate Airport IFR Weather Minimums are prescribed by Operations Specification (Ops Spec) C055, specifically Table 1 of that specification. Below is a generic ...
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2answers
335 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 ...
7
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1answer
247 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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1answer
113 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 ...
0
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2answers
138 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?
17
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3answers
3k views

What makes flight recorders harder to find than tagged sharks?

It really bothers me that we can't find planes that weigh tons with black boxes (AFAIK) technology that's almost obsolete, on the other hand shark tags (AFAIK) work great for long time and we can ...
4
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1answer
663 views

Why did my phone's GPS receiver stop working when the plane was descending to land?

Recently, I flew on an Airbus A320. I turned my Lenovo A328 Android phone into airplane mode, and then used the default Maps app to watch my position using GPS. For most of the flight it worked ...
20
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5answers
9k views

Why is there a difference between GPS Speed and Indicator speed?

I just played with flight simulator and noticed that the GPS shows different speed from the speed indicator in the cockpit. Also, GPS speed is higher than the Indicator. Any Idea why?
0
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1answer
226 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 ...
2
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2answers
421 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. ...
3
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2answers
334 views

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 ...
28
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6answers
20k views

How do airliners cross the ocean without GPS?

How do airliners cross the ocean without GPS? Do they use dead-reckoning or are there navigation aids floating out there?
5
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1answer
256 views

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 ...
17
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4answers
18k views

Is LPV considered a precision approach?

WAAS LPV approaches can have decision altitudes as low as 200 AGL, the same as many Cat I ILS approaches. Previous opinions on the Internet have quoted the FAA as saying LPV is considered a non-...
0
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1answer
107 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?
5
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2answers
539 views

Can I use my non-WAAS GPS receiver with ADS-B in the United States?

I have a older style Garmin 530. Can I use this GPS as the position source for an ADS-B installation?
5
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1answer
2k views

Why does Boeing 737 use 2 Inertial Reference Systems (IRS) and GPS?

According to this website the Boeing 737 aircraft use 2 IRS and 2 GPS: IRS L & IRS R. Why? Apparently they are totally independent of each other. Could somebody explain a little bit why they need ...
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4answers
441 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 ...
28
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6answers
16k views

Is it possible for a modern commercial airliner to stop being tracked without substantial mechanical failure?

I was speaking to someone about the MH370 incident, and they suggested that a hijacker could turn off the device that sends the plane's current position, resulting in the appearance of a catastrophic ...
2
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1answer
283 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) ...
5
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1answer
478 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 ...
7
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2answers
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 ...
16
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3answers
8k views

Why isn't an LPV SBAS approach considered a precision approach according to ICAO?

According to ICAO's classification, LPV SBAS approach is in the APV group, because it doesn't meet some specifications for precision approaches. But what exactly does it not meet? Glossary: LPV: ...
2
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1answer
595 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 ...