Questions tagged [gnss]

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

Filter by
Sorted by
Tagged with
1 vote
0 answers
25 views

Along Track Distance ATD

ATD (Along-Track Distance) is used by ATC for certain types of (rare) NON-Radar Separation. I am training as an Air Traffic Controller in the USA. I have been told the only way to know if an aircraft ...
user avatar
4 votes
0 answers
72 views

How to reduce the volume of the GTN750 traffic warning beep?

We've got a GTN 750 with ADS-B IN and OUT. When we encounter traffic it emits a high pitched pulsing beep. It cannot be muted by any means - say you are on final and there's an aircraft holding short ...
user avatar
7 votes
1 answer
228 views

Do GPS systems in modern avionics mitigate against spoofing attacks?

There exist a number of different techniques [PDF] to mitigate (or at least detect) GPS spoofing, but the most effective techniques require access to the military-only M-code [PDF]. However, there was ...
user avatar
  • 217
14 votes
4 answers
4k views

Do airlines use GPS for critical purposes? If so, why?

It is being reported that airlines in Finland have noticed interference with their GPS signals near Russia. This is causing them to be unable to land at at least one airport: Lithuanian airline ...
user avatar
  • 259
3 votes
1 answer
509 views

How to track a flight that I am flying in using the GPS antenna in my mobile phone (without internet)?

I am in India. I booked my first flight ticket a few weeks ago and am very interested in identifying locations as well as geographical and human structures that I will see. I have downloaded many GB's ...
user avatar
17 votes
3 answers
3k views

What are satellite time, GPS time, and UTC time?

What is the difference between Satellite time, GPS time and UTC time? How are these calculated from one another?
user avatar
5 votes
1 answer
208 views

What does a DME indicator do in HOLD or RNAV mode?

I found this DME indicator on the Cessna 210. Its mode switch has four positions - NAV1, NAV2, RNAV and HOLD. NAV1 and 2 are clear - it uses the NAV1 and 2 freq respectively. I'm wondering what the ...
user avatar
0 votes
1 answer
384 views

Can single engine/smaller aircraft turn off ADS-B?

I was just looking at the adsbexchange website, and was wondering if it was possible for smaller, private aircraft to turn off their ADS-B? I was wondering this because id figure that maybe not ...
user avatar
2 votes
1 answer
232 views

Do the regulations allow DME from an expired IFR-certified GPS with an out of date database to be used for this ILS approach under an IFR plan?

Since we cannot fly an RNAV approach with out of date GPS database, the approach in question is KCRE ILS 23. Whether it was asking for V2F or the full approach starting from ASHES (which is 18.5 DME ...
user avatar
7 votes
1 answer
2k views

How does drone reliance on GPS make it 'semi-stealthy'?

I saw this on CNN today. For months, US intelligence and military personnel in Iraq have been raising alarms about the risk to American forces from these newer, more sophisticated Iranian-made drones....
user avatar
5 votes
1 answer
346 views

Why do some GPS receivers suppress RAIM integrity warnings after you pass the FAF?

RAIM performs an integrity check 2NM from the FAF. If RAIM is lost before the FAF, one should execute the missed approach. However, if RAIM is lost after passing the FAF, some GPS receivers will ...
user avatar
  • 51
1 vote
1 answer
145 views

Why are SBAS-equipped planes exempt from the preflight prediction check?

My question stems from this other question: Why is training regarding the loss of RAIM given so much more emphasis than training regarding the loss of SBAS? Two answers say losing RAIM puts a question ...
user avatar
6 votes
2 answers
753 views

Why weren't SA-On GPS units updated to become SA-Aware?

SA = Selective Availability (gps.gov) SA-On and SA-Aware are widely used in current air transport aircraft (...) GPS that behave as if SA is still active (SA-On) GPS that behave as if SA has been ...
user avatar
0 votes
3 answers
241 views

What kind of airspeed does a (3D) GPS measure?

Assuming a GPS receiver is advanced enough to compute 3D position/velocity with reasonable accuracy, it can indicate not only the aircraft's ground speed (which ignores altitude changes), but ...
user avatar
  • 109
-4 votes
1 answer
84 views

Find the course or heading of an object [closed]

Im working with orientation using GPS + IMU, and before the actual implementation of the program, im working with simulation using a dataset that provides me some GPS data, such as latitude, longitude,...
user avatar
10 votes
2 answers
3k views

Why is training regarding the loss of RAIM given so much more emphasis than training regarding the loss of SBAS?

I've noticed a lack of subject matter on the loss of SBAS as compared to RAIM. In the ACS there is mention of RNP, SBAS (WAAS), and RAIM, which are all related, but the available content for RAIM and ...
user avatar
-3 votes
2 answers
179 views

What is the purpose of aircraft localization? [closed]

I want to understand what is the purpose of doing localization while an aircraft is flying? What sensors are used by the instruments that do this localization of an aircraft? Is there more than one ...
user avatar
  • 155
6 votes
2 answers
2k views

Why RNAV SIDs and STARs are RNAV 1 instead of RNP 1?

I am studying for my CFII check-ride and I was wondering to know why SIDs and STARs are not RNP 1 but RNAV 1? Let's start with the following two definitions RNP - Required Navigation Performance: It's ...
user avatar
0 votes
1 answer
175 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.
user avatar
  • 103
0 votes
1 answer
189 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 ...
user avatar
  • 927
3 votes
1 answer
232 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) ...
user avatar
  • 137
8 votes
1 answer
161 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 ...
user avatar
4 votes
1 answer
211 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 ...
user avatar
1 vote
1 answer
96 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 ...
user avatar
  • 131
2 votes
3 answers
2k 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?
user avatar
  • 139
0 votes
1 answer
301 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?
user avatar
0 votes
0 answers
30 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?
user avatar
5 votes
1 answer
1k 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 ...
user avatar
  • 6,325
1 vote
0 answers
181 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 ...
user avatar
  • 6,325
2 votes
1 answer
351 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 ...
user avatar
  • 54.1k
1 vote
2 answers
1k 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?
user avatar
  • 559
3 votes
2 answers
166 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?
user avatar
  • 91
2 votes
1 answer
576 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 ...
user avatar
  • 438
2 votes
1 answer
863 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?
user avatar
20 votes
6 answers
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 ...
user avatar
2 votes
1 answer
284 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 ...
user avatar
-1 votes
1 answer
124 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 ...
user avatar
0 votes
2 answers
141 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?
user avatar
  • 11
7 votes
1 answer
250 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
user avatar
1 vote
1 answer
678 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 ...
user avatar
2 votes
2 answers
782 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. ...
user avatar
  • 1,589
3 votes
2 answers
412 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 ...
user avatar
  • 4,556
5 votes
1 answer
421 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 ...
user avatar
0 votes
1 answer
112 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?
user avatar
1 vote
4 answers
532 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 ...
user avatar
2 votes
1 answer
598 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) ...
user avatar
7 votes
2 answers
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?
user avatar
  • 457
5 votes
1 answer
551 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 ...
user avatar
  • 159
7 votes
2 answers
4k 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 ...
user avatar
  • 3,284
3 votes
1 answer
7k 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 ...
user avatar
  • 611