I was looking at a flight that had this listed as the route:

JAG6 MATEO SHRKS Q77 WIGVO IRQ J85 SPA HNN SUBWY HTROD2

I seem to recall multiple lines like that on flights I have taken in the past. Is there a simple way to understand what this type of entry refers to?

While there are no roads, I for some reason imagined this type of thing referred to some standardized path across the sky - virtual roads. No idea if that is correct or if it some code for a random path, etc.

Anyone able give us a simple guide to understanding this?

SIDS with a transition, an airway portion, some direct legs, then hook up to a STAR for the arrival.

https://www.vatsim.net/pilot-r...ssons/sids-and-stars

Normally one gets a shortcut or two, depending on airspace, traffic, weather, whatever. You can imagine during busy times(pre-Covid) 6 arrivals feeding into ORD, or wherever.

I'm not a pilot, my brother is, so here is a simple explanation: In a simple way of stating, nothing technically explained, They are "waypoints" in the invisible sky. The ones you listed are "locations" the plane must fly to, from one to the next, in order to maintain order in the sky, so no collisions or messy situations.

That, along with assigned altitudes by air traffic controllers, provides efficiency and safety.

If you were to look at a flight tracking website, such as ABS-D Exchange, and look at a somewhat wider view, you'll see an over head view of planes entering into a pathway to land at really busy airports, such as DFW. You'd see a clear lineup of planes, from different directions, getting into this line from hundreds and hundreds of miles out, to arrive and land.

That's what the waypoints do, they get planes not only routed to where they want to go, and also how to approach a busy airport and land, safely and efficiently, the to make the jobs of the air traffic controllers easier and simpler and hopefully no mistakes so we all get to where we want to go alive and well.

A pilot will file his flight plan and ATC will acknowledge back with OK or they might want him to hit a different waypoint, possibly due to bad weather or NOTAM's, many of which are temporary, so he won't get busted and big big trouble. For example, when the President is visiting someplace, you are not allowed to fly over it while he's there.

I hope this helps, I'm not a pro, just what I've learned from my brother, and my brother in law, now deceased, had a private jet and I was always asking the pilots questions about how they do their job.

If you were to look at an aviation navigation chart, you would see that the five-letter groups, like "MATEO" are waypoints. The three-letter groups, like "IRQ" are VOR stations. Character groups like "J85" are airways -- highways in the sky, as it were.

As sourdough said, JAG6 would be a Standard Instrument Departure (SID) and HTROD2 is a Standard Arrival (STAR) procedure.

So, the flight route is defined by the departure procedure from the originating airport, then a series of waypoint-to-waypoint and / or airways, and an arrival procedure.

(I teach this stuff in ground school)

I just noticed a lot of those abbreviations are related to the area. Things like Hot Rod in Detroit, Disney names for Orlando like Hakuna and Mattata, Red Bird for something in Louisville.

quote:

Originally posted by Oz_Shadow:

I just noticed a lot of those abbreviations are related to the area. Things like Hot Rod in Detroit, Disney names for Orlando like Hakuna and Mattata, Red Bird for something in Louisville.

Yes, this is true for the five-letter waypoints. I don't have a chart in front of me, but I think I remember something like "GITAR" in the Nashville area, "GOOFY" in the Disney area, and there are some that are named after local aviation people as well.

The real requirement is that each name is unique.

One of our Air Traffic Control members might be able to go into this in more detail. I know it from the pilot's perspective, but I'm sure that there's more to it than that.

quote:

Originally posted by Oz_Shadow:
I was looking at a flight that had this listed as the route:

JAG6 MATEO SHRKS Q77 WIGVO IRQ J85 SPA HNN SUBWY HTROD2

I seem to recall multiple lines like that on flights I have taken in the past. Is there a simple way to understand what this type of entry refers to?

While there are no roads, I for some reason imagined this type of thing referred to some standardized path across the sky - virtual roads. No idea if that is correct or if it some code for a random path, etc.

Anyone able give us a simple guide to understanding this?

JAG6 is a coded instrument departure; the path leading from the airport. Called a SID (Standard Instrument Departure) or DP (Departure Procedure), it will include altitudes and points in space, fixes, defining a path the aircraft follows to leave the airport, and transition to the enroute structure. The SID will typically also include radio frequencies for Air Traffic Control communication, weather and airport information, etc.

MATEO and SHRKS are five-letter identifiers of waypoints beginning in Florida and heading north. These points will be used to fly over, after departing, to start the path north.

SHRKS is the point at which the flight will join airway Q77, and the aircraft will stay on that airway until reaching waypoint WIGVO.

From WIGVO, the flight will proceed direct to IRQ VOR (very high frequency omnidirectional range: a radio beacon): Colliers VOR.

At IRQ, the flight joints jet airway J85 to Spartanburg VOR (SPA). Airways are used to define longer paths that may include multiple waypoints, to eliminate needing to identify all the waypoints. They connect navigation aids, such as VOR's. Some airways, to include Q77, are defined by waypoints that are coordinates (eg GPS coordinates).

From SPA, the flight goes direct to HNN VOR (Henderson, WV), and thence direct to SUBWY intersection.

The arrival is conducted using the STAR (standard terminal arrival) Hot Rod 2 (HTROD2) procedure. This works the same as a SID (Standard Instrument Departure, also DP, or Departure Procedure), except is used for arriving. It will include all the fixes and altitudes necessary for the arrival, as well as a set of instructions in the event of a lost-communication scenario. It will also include frequencies used for air traffic control, obtaining airport and weather information, and so forth.

Very interesting. Thanks. I am guessing a computer does a lot of this with all those waypoints stored, but if it goes down, how do you know where to go?

In the most basic form of navigation, you plot your desired course on a chart. You know your aircraft's cruise speed, so x minutes at x knots in x direction takes you from point A to point B. In practice you have to adjust those heading and speed numbers to account for winds aloft, as they will affect the speed and course your aircraft is actually travelling over the ground.

quote:

Originally posted by Oz_Shadow:
Very interesting. Thanks. I am guessing a computer does a lot of this with all those waypoints stored, but if it goes down, how do you know where to go?

The route information listed at the outset is the description of the route to be flown. Navigating that route takes various forms. One might navigate to a fix based on radar vectors, or in other words, directions from an air traffic controller, using magnetic headings to fly. One might navigate using GPS, or one might navigate using ground-based radio beacons, such as the VOR.

Visually flying, one looks out the window and identifies landmarks.

In instrument flight (when flight plans are filed using the routing described), one can't count on being able to look out the window, so the routing is predicated on other forms of navigation. Most aircraft use multiple forms of navigation.

Airline and some corporate aircraft use inertial navigation, which uses sensitive accelerometers to sense movement: the initial coordinates are input before the aircraft moves, and without referring to any outside sources, the units sense the direction and rate of movement, to determine where the aircraft is. INS and IRS use solid-state and laser-ring gyros, typically three inputting their individual calculations, to determine a position. Those are mixed with external information such as GPS, and the use of ground based distance-measuring equipment (DME/DME) to determine location. If one system goes down or is compromised, multiple backups are available.

Today, navigation is extremely precise, and it has to be, because of the amount of traffic in the air. It's so precise that we routinely fly half-way across the Atlantic and are exactly over or under another aircraft on routing the same way or opposite direction, and we will offset our course up to two miles to the right to add some randomness for safety.

While long oceanic routes use required navigational performance (RNP) of 10 (within 10 nautical miles of position 95% of the time), lowered values over busy routes are down to RNP4, and instrument arrivals are .3 RNP, with approaches being within a few feet.

While we don't do it domestically, when on long legs over oceanic areas where there are no ground-based navigational aids (Navaids), we do backup plotting and verification; many still do so on paper charts called plotting charts, to crosscheck and verify that we're going where we're supposed to go.

Domestically, we have external observation in the form of Air Traffic Control and radar, and now ADS-B, which uses aircraft and ground equipment to also track position of each aircraft, and each aircraft relative to every other aircraft; the controller sees all the ADS-B-out information and has a great deal more knowledge about what's going on with the airplane than ever before. In fact, in our aircraft, ATC can notify us if we make an incorrect input, before we ever actually execute it or make it happen in real time.

Last year I had a dual FMS failure over the Pacific, in which we lost all our navigation, and standby navigation. We were doing what is called Class II nav, meaning no ground navigation aids, and no radar contact, passing all our communications through radio operators on HF radios (mostly occasional position reports). Our only remaining navigation was on ipads, and the GPS signal they received. Our immediate solution was to establish heads and dead reckoning practices (time, distance, airspeed), and reference the ipads for awareness and correction. We were able to recover nav and continue, but it does go to show that even with multiple sources and redundancy, it can happen.

Didn't a lot of planes, many years ago, have a window or something on top to take a, what was it called, a sextant? And shoot the stars and do some fancy math to figure out where they were?

I assume this may still be done on ships at sea.

Today we take GPS for granted, and it's not a big deal in driving ones car around, but I think it might be a huge problem if something happens to the GPS system for airplanes over the ocean with no place to land if fuel runs low. Or not, I don't know, I'm just curious.

Don't the Russians and the Chinese and some other governments have their own version of GPS up and operating?

Thank you for this topic and your replies, I find it fascinating.

(I've never wanted to get a pilots license but I've thought about just taking the ground classes just to learn more about meterology and navigation, etc, as I am a very curious person who loves to learn new things every day).

Thanks again.

quote:

Originally posted by OKCGene:



Thank you for this topic and your replies, I find it fascinating.

(I've never wanted to get a pilots license but I've thought about just taking the ground classes just to learn more about meterology and navigation, etc, as I am a very curious person who loves to learn new things every day).

Thanks again.

I do as well. I don't think I could convince the wife to let me pay for the seat time as a hobby, but it is fascinating enough to make you want to learn at least the basic stuff.

The closest I may get is boating on large lakes visually and by GPS.

quote:

Originally posted by OKCGene:
Didn't a lot of planes, many years ago, have a window or something on top to take a, what was it called, a sextant? And shoot the stars and do some fancy math to figure out where they were?

I assume this may still be done on ships at sea.

Today we take GPS for granted, and it's not a big deal in driving ones car around, but I think it might be a huge problem if something happens to the GPS system for airplanes over the ocean with no place to land if fuel runs low. Or not, I don't know, I'm just curious.

Don't the Russians and the Chinese and some other governments have their own version of GPS up and operating?

Some of the airplanes I used to fly had astrodomes, which were used for taking celestial readings (star readings) for celestial navigation. Even the early 747's I flew had a smoke port which was also originally available for a celestial periscope (sextant). The first 747-100's were equipped with the mounting and sextant. I don't believe they were used.

Celestial navigation involves identifying specific celestial fixes (stars) and their position above the horizon, relative to the aircraft, and the time; using that and sidreal tables that give star positions throughout the year, one can plot a position, and then use several plots to determine winds aloft, groundspeed, wind correction angles, etc. That information, in turn, is used to make position fixing more accurate and to enhance dead reckoning naviation, which plots position based on time, wind, airspeed, temperature, altitude, etc.

Modern navigation has put constellations in the sky for satellites that deliver precise timing and position information, but the navigation works exactly the same...except that computers do the observation and calculation. Same thing that works in the Tom Tom in the car, or GPS on an iphone or watch.

Fuel calculations are done by quantity, weight, and time, as well as temperature (temperature affects volume, but not weight), and of course fuel consumption. If I'm burning 24,000 lbs of fuel/hour and it's four hours to the destination, a rough calculation tells me that it's going to take 100,000 lbs of fuel burn to get there. Rather than rely on that rough calculation, however, my written flight plan will tell me every waypoint I plan to pass over on the way (there may be hundreds). Each one will have a calculated time of passage, and fuel remaining. At each waypoint, or every few waypoints, the fuel remaining is noted, as well as the time over the waypoint, and we'll determine if we're overburning or underburning, by how much, and how that impacts the flight. Same for time; the time difference affects subsequent waypoint passage, estimated time of arrival, etc. These also figure into planning diversions due to weather, onboard emergencies, depressurization, etc...especially on really long legs in remote areas with few options. Equal-time point calculations are made, noting a place where the same time exists to go forward, or go back, with an emergnecy...in those cases, the fuel minimums are substantially lower than what are found in most situations...15 minutes of fuel remaining at the ETP alternate. Knowing one's fuel becomes very important.

Onboard equipment calculates this, but we back it up with our own observations and calculations. Not doing so is complacency that's headed for disaster.

The GPS constellation is courtesy of the US military. The Russian system is called GLOSNASS.