# Questions tagged [fms]

An FMS is a specialized computer system that automates a wide variety of in-flight tasks, reducing the workload on the flight crew. A primary function is in-flight management of the flight plan. [Wikipedia]

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### Which trigonometric algorithm does an FMS use to determine distance between waypoints?

When entering waypoints into an FMS, the FMS calculates bearing and distance between them. Does it use "normal" spherical trigonometry equations, or go for the more accurate Vincenty algorithm which ...
4k views

### How do pilots set the exact amount of thrust needed for a reduced power takeoff?

I know jet-powered airplanes very rarely use 100% available power for takeoff, and most often reduce power to increase engine life. How does a pilot set thrust to an exact level? The airplanes I'm ...
1k views

### Why are true headings followed above 73N in the northern hemisphere, whereas in the southern hemisphere the change is made at 60S?

The question is in regards to the asymmetry of the changeover latitudes and NOT about why it needs to be changed.
1k views

### What are those 5-character alphanumeric waypoints?

On the following High IFR chart from skyvector.com I notice along the meridian at 30' intervals there is a green symbol the same shape as an RNAV waypoint. Next to them are 5-digit identifiers, but it ...
984 views

### Why is air traffic control done manually by humans?

I'm not a pilot but have a software developer background, so forgive my aviation naivety. From what I understand there have been numerous issues and almost-issues relating to human air traffic ...
3k views

### What is the FMS Bridge Visual 28R approach at SFO?

I've read that SFO has a specialized FMS Bridge Visual approach to 28R that is not published but instead is custom tailored for specific operators. What exactly is this approach and how does it work? ...
664 views

### How does an FMS shift after losing all external navaids?

It's not uncommon for polar flights to lose GPS signal (ionosphere issues due to the high latitudes). But it is not a concern because the typical IRS drift is 650 meters for every hour of flight, and ...
413 views

### Which commercial aircraft can fly Micro-SLOP procedures?

"Strategic Lateral Offset Procedures (SLOP) are approved procedures that allow aircraft to fly on a parallel track to the right of the centre line relative to the direction of flight to mitigate ...
662 views

### Why can't flight management systems receive instructions directly from the controller?

If an aircraft's flight management system has auto pilot and auto thrust coupling, and it can make changes to the aircraft speed and direction along the entire route without pilot intervention, then ...
3k views

### Does the Fokker 70/100 Flight Management Computer really contain the ability to play Pong?

This clip now circulating on Facebook (YouTube link) shows two pilots playing a game of Pong on the Fokker 70/100 Flight Management System (FMS). The manufacturer is presumably Honeywell. Does this ...
3k views

### What is the relationship between “automatic flight control system AFCS”, “autopilot”, “flight director” and “flight management system FMS”?

I'm studying aircraft maintenance. I looked in my books and searched the web but couldn't make a big picture of the concept of autopilot. Specifically what is its relation to modern systems like FMS....
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### How does the FOVE system work with the Airbus FMS?

The Flight Operations Versatile Environment (FOVE) is a separate software system used with Airbus aircraft by dispatchers to determine performance data to enter into the FMS. There seems to be little ...
346 views

### How do oceanic lateral offset procedures work?

I was reading a forum for professional pilots and ran across a thread on lateral offset procedures during oceanic flight (apparently having the FMS offset the aircraft from the centerline of an ...
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### Is the 737's autopilot part of the FMS or is it a separate entity?

I was watching a tutorial about the FMS and the autopilot in the 737, and I am consfused. I come from a Cessna background, where there is no FMS, there is only the AP (autopilot). So, is the AP a ...
7k views

### What is the ALT INTV on the 737's autopilot?

So, I was watching a quick tutorial on the FMC on YouTube. The FMC somehow had a 5000 ft restriction, and the guy got clearance to go higher up, and he set his altitude on the AP panel, and he pressed ...
4k views

### May pilots perform FMS database updates under Part 135?

Are pilots allowed to perform FMS database updates under part 135? If so, do they need formal training entered in their pilot records before they are allowed to do it?
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### What type of computers are in a flight system?

I know there are many types of flight computer systems, with varying names and capabilities. I'm more interested in knowing what the computers, themselves, are made of? They certainly are not "off ...
436 views

### Are sequenced waypoints still displayed on the Navigation Display / FMS legs page?

This question relates to the Flight Management System of a large airliner, e.g. Boeing 787: During a flight, when the aircraft passes a waypoint, is this just passed waypoint (and the previous ones) ...
414 views

### Is it possible to disengage only one axis of a two-axis autopilot?

Take GFC700 for example, when autopilot (or flight director) engaged, the lateral mode falls into ROL, HDG, GPS, VOR, VAPP, LOC, BC, ... and the vertical model has to fall into PIT, ALT, FLC, VS, ...
1k views

### Why are the character keys on the Flight Management Computer in alphabetical order?

Regardless of which aircraft type and manufacturer, the character keys on any Flight Management Computer are always in alphabetical order, see image: From a human factors view, this is sub-optimal, ...
15k views

### What's the difference between FMS and FMC?

What's the difference between FMS (Flight management System), and FMC (Flight management computer)? Can the flight management computer be thought of as what's manipulating the input information from ...
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### How to program an FMC if the database is missing the arrival airport?

Let's say you are in a 737 flying to Geita, Tanzania, as you can see this little airport/airstrip has an IATA code, but not an assigned ICAO code. What should you enter into the FMC if I want to fly ...
4k views

### What are fuel biases?

Does anyone have an idea of what is it? From what I gathered from the web, it seems that this is the margin of error between the actual, real fuel consumption of the aircraft and the fuel consumption ...
248 views

### Does the A320's FMC automatically adjust the rate of descent on a non-precision approach?

Does the A320's FMC automatically adjust the rate of descent on a non-precision approach? Like a back course approach for example if the distance to altitude is (or can be) programmed in?
392 views

### In G1000, how can I intercept a victor airway with multiple legs?

Suppose we are in HDG mode. Trivially, we may visually judge which leg we on the victor airway and activate that leg. However, in real-world, I found sometimes the fixes are so close and the ...
185 views

### Where can I find an image of the Thales FMS220 RMS page?

I'm looking for photo/color image showing Thales FMS220 RMS (Radio Management System) page. Also COMMUNICATION and XPDR pages are highly welcome.
212 views

### Can SID/STAR have shortened names?

I have a strange naming difference for a SID in a route. The route is: DOME4W DOMEG Y841 ANAVI DCT NVO UM170 KENUM UM615 IDOSA UN857 RESMI UN491 DITAL UN872 DIDAK UZ15 ARDOD A5 VALAX VALA1A I am ...
248 views

### Do modern aircraft automatically manage the deceleration to Vref?

Typically in most aircraft, the pilot manually reduces the speed gradually until reaching the landing zone/flare zone. Modern aircraft have FMC. Does the FMC automatically manage the speed gradually ...
128 views

### Why don't FMCs automatically include up-to-date oceanic route definitions?

In modern FMCs, flying an oceanic route requires inputting coordinates directly, often in obtuse formats (which are arguably prone to typos, but following proper procedure and a step through the route ...
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### What do the different types of approach abbreviations used on the A320 MCDU exactly mean?

On the MCDU I have noticed after setting up the approach there are a number of different codes which appear next to the runway designator these are namely as below: CI CF FI CD FD Can someone kindly ...
1k views

### What are these “F,S,O” characteristic speeds?

I am leaning for an avionics exam and I encountered a question asking for the meaning of F, S and O . They appear to be "Characteristic speeds", which are calculated by the flight management system (...
114 views

### Garmin 530: What is NXRG telling me?

I have a Garmin 530 in a Cessna 550. It has a constant display of NXRG:x:xx in the upper right corner of a map page. It changes color (yellow and green are common) ...
121 views

### For a coded departure procedure (SID), Fly-At-Altitude or At-Waypoint instruction has priority in case of conflict?

I am examining various RNAV departure procedures and especially those whose purpose is to overlay the existing conventional ones. I noticed that some of them begin with a "Flight at Altitude" ...
328 views

### How does ADS-C and FMS relate to FANS?

So - I'm totally confused about FANS and its systems. From what I understand: FANS 1/A (started in 90s) has some early CPDLC for USA routes (this topic) but what about position reporting? Does it ...
1k views

### How did KAL 007 get so far off course?

Regarding Flight 007 that got shot down in the Soviet Union, this was reported in the New York Times: Study Says Korean Airliner Was on Its Intended Course When Downed in '83 (nytimes.com) Excerpt: ...
836 views

### Is the flight management system software independent from the hardware?

Is it possible to 'mix and match' hardware and software from different vendors to make a flight management system? I want to prepare a study about FMSes and I can see that there are several ...
248 views

### Is there an FMC not connected to the AP/FD?

Is it possible to have an FMC to compute the performance and navigation without having it linked to an autopilot or flight director? Does/did such setup exist?
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### Why does the CRJ100/200’s FMS miscalculate temperatures at altitudes in excess of 36k feet?

The CRJ100/200’s flight management system (FMS) apparently is not to be used to calculate engine thrust settings when the aircraft’s altitude exceeds 36,000 feet, due to internal calculation errors at ...
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### Current FMS with COMM tunning function capability?

I am currently more familiar with GARMIN 1000 systems than with the ones that are used nowadays in airliners. I know that you can tune a NAV aid from the FMC in an airliner. Actually, modern FMS ...
292 views

### Where does an FMS wind information comes from to calculate V approach?

To calculate the V approach the FMS is using a wind either taken by the ADIRS or inserted on APPR PERF page. At first I will say that it takes the wind inserted by the crew, but I am not completed ...
428 views

### What name is given to an abeam waypoint in the FMS?

In a Flight Management System, what name is given to an abeam waypoint in case of DIR TO? Is this name format different in Thales and Honeywell FMS?
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### Is the modelname of a flight management system chosen in accordance with the aircraft it will be used on?

I am looking for information about what modules (not necessarly partnumbers) are used in a flight management system of a relatively new airplane. After having looked around for quite some time, I ...
87 views

### When does the FMS in the 737NG switch to approach mode?

I fly a B737-800, and we talk about when the FMS enters "Approach mode". At this point, the FMS will command the Vref (plus additive) at the appropriate flap setting. This is helpful to know ...
99 views

### What does the ACARS Weight and Balance Request page look like?

In the ATSU AOC Preflight menu of an Airbus (maybe Boeing too), there is an option for a weight and balance request. The selection name varies by airline but it may say "W/B Req" "Send ...
191 views

### How should I read these abbreviations on the Airbus 320 MCDU?

Often I have seen some abbreviations on the Airbus MCDU such as CI, CF, etc. They are explained in this question: What do the different types of approach abbreviations used on the A320 MCDU exactly ...
33 views

### Flight management System(FMS) related to Performance Managment

What are the recommends criteria and requirements for a Flight Management System (FMS) for transport aircraft related to Performance Database or Performance Management
128 views

### is it possible that setting a lower airspeed makes a steeper climb?

I'm now studying a Flight Management System (FMS), and it says that when the FMC predicts that the airplane will not reach an ALT constraint, the CDU will display "UNABLE NEXT ALT" and then ...
89 views

### What is the difference between a navigation database and an airport mapping database?

What is the difference between "navigation database" and "airport mapping database"? Are those both required by flight management software for flight planning?