I am tracking my daughter’s flight from JFK (New York) to Tel Aviv. Several of the flight tracking sites show the plane departing from the regular flight path over Europe and flying to Denmark, then returning to the regular flight path. The plane never diverted, and is still showing that it will be on time in Tel Aviv. Why would the flight trackers show this?
When you say “regular flightpath” what do you mean? If the site is assuming a simple great circle route, it is very common that overland flights do not follow such routes for traffic, regulatory, or weather reasons.
Small deviations 10 or 30 miles off to one side or another are completely routine.
Security perhaps?
The plane might have been avoiding a storm or some restricted airspace. It’s fairly common for flights to deviate from the most direct or most typical flight path for various reasons and the extra time is usually accounted for in the arrival time. Had the aircraft taken the idealised route it might well have arrived early.
Do you have a link to the flight on the tracker?
It looks like some El Al flights to Tel Aviv are planned via waypoint VES in Denmark. My guess is that at the flight planning stage they need to refuel there but once airborne they can recalculate their actual fuel and fly direct.
The flight tracker would assume the aircraft was on the planned route, only updating its actual flight path some time later.
The deviations can be quite a bit larger than that. I’ve flown from Michigan to Japan several times, and the midpoint of the outbound flight track is always several hundred miles north of the inbound flight track - and the latter is a good 500-600 miles south of the true great circle route. It should be noted though that for a flight this long (>6000 miles), a lateral deviation like that results in a surprisingly small increase in path length.
A GC route from JFK to Tel Aviv would pass over Paris, a good 500 miles SW of Denmark, with a total flight length of 5665 miles. Deviating from the GC so as to pass over Denmark increases the flight length to 5763 miles, just 100 miles more.
Good point about deviations from GC. Those can be hundreds of miles due to optimizing for the wind or th traffic flow or whatever.
I wasn’t being very precise.
I’ve never played with any flight tracking app, so I don’t know how much they/it knows the actual flight plan as filed by ATC, the clearance of the moment as amended by ATC, or simply assumes GC from liftoff to touchdown.
So I was thinking of and (implicitly) referring to the other sorts of deviations from the immediately cleared route. Which are usually flown free-form 10 to 30 miles of the nominal track due to traffic, administrative ATC boundaries, or avoiding severe weather.
Two very different sorts of “deviations” from two very different sorts of plans.
I do know the flight progress app on the seatback entertainment systems of our airplanes assume a simple GC from liftoff to touchdown. As the flight progresses, they don’t show where you’ve been, just a GC from present position to destination. Which often means the airplane symbol is shown as flying at some 10, 20, or even 30 degrees off of the direct track to the destination. Becasue that’s what we’re really doing for many reasons. Many of which are not “deviations” from our POV; we’re just executing a planned track as planned that is less than geometrically ideal.
I’d be curious if the OP can tell us which app they used and whether they or anyone else can tell us whether the common flight tracking apps purport to know and display the current ATC clearance, the filed flight plan, or just assume a GC.
If you click my link it should show the flight in question (there weren’t many options, I suppose it could be an earlier one). That website shows the planned route as a dotted line and on the side panel it has the filed route, airways, lat longs, etc. Waypoint VES is a VOR up in Denmark and is part of the filed route but was not actually flown. It increases the route distance significantly because it is planned as an abrupt diversion from something close to the abeam point. Looking at other similar flights in Flight Aware you can see that some are planned with the Denmark leg and some aren’t.
Actually, I’m still trying to work out what the Denmark waypoint is.
Right, I think I’ve worked it out. You can go to a website called Sky Vector that lets you play with a world wide nav database.
If you go to the Flight Aware link I posted earlier, copy the filed route,
KJFK BETTE ACK DOVEY 4200N/06000W 4400N/05000W 4600N/04000W 4700N/03000W 4700N/02000W 4600N/01500W BEGAS VES LASKU UM190 BLV UM601 BCN UN725 ORKUM UM603 ELSAG ALG POKAV UNIXO LATAN TRL UM601 MIL UN134 VANZA N134 BIRES Z89 PIKOG L609 ZUKKO LLBG
then select “Flight Plan” on the top left of the Sky Vector website and paste the route into the route section on the pop up window it displays a route that is close to the actual route flown and doesn’t include anything in Denmark.
VES in Sky Vector is a waypoint on the north coast of Spain. However VES may also be a waypoint in Denmark. I found a navaid overlay for Google Maps that shows VES in the same position that Flight Aware does.
So, my theory is that Flight Aware is using an incorrect location for VES and that the flight was never planned to go anywhere near Denmark.
To further confuse matters, if you click “Decode” on Flight Aware, it gives a latitude / longitude for VES that is somewhere in the USA, wrong, but a different wrong.
Very interesting. My work iPad has a Jepp full planet subscription at least for enroute. Though it lacks lots of airport plates and low VORs. Thanks, Boss.
My Jepp does not recognize that VES VORTAC in Denmark. Although I agree w your sites/cites that it’s there.
Jepp does show the VES = Asturias VOR on the north coast of Spain. And there is no VES in the USA either in our charts or in the textual listing of Navaids. Google and the internet seem to agree.
I keystroked in the relevant chunks of the route you cite and got the same results as Skyvector did. VES (or at least the one that matters) is in Spain.
So the idea that they filed over and more or less overflew the VES in Spain makes complete sense.
That Flightaware bit off on the wrong VES and drew the line on the browser via Denmark also makes complete sense too.
Duplicate navaids & fix names are a bane of our existence. We have one here in the Caribbean where the same fix ID is found at about 20N and at 20S both at about 60W. Talk about an easy mistake to make. Of course it scrambles the uploaded route data every time and takes a bunch of error-prone keystroking to fix.
AIUI the industry has a plan to eliminate all duplicate waypoints by around 2050. I’ll be over 90 by then, so it ain’t gonna be my problem.
Made a bit of a hash of the above with delayed then rushed edits. The punchline remains that you figured it out correctly & my gear corroborates your interpretation.
Sky Vector didn’t have it either, but it does have the VES in the USA, see below.
A bit obscure. It is a small airport in Ohio. Not the sort of thing that would be in an airline nav database.
This is the lat/long that Flight Aware’s decoded flight route was pointing at. They must use a different database for the decode vs the map display.
Move to New Zealand and enjoy the freedom of being able to fly passenger jets for as long as you can keep your medical! Our anti-discrimination laws trump any ICAO mandated retirement age.
Part of the edit hash I made that never got posted was that I did see a bunch of high & low airways converging where the VES VORDME is in Denmark. So it’s clearly there, just not in my database. Go figure.
And we do show the VES/KVES airport in Nowheresville, Ohio. But there’s no navaid by that ID. I’d been searching for navaids. As a general matter (as you of course know, but the audience probably doesn’t) airfields are not used as enroute navigational fixes. Co-located or nearby radio beacons are fair game though. Which often, but not always, have the same identifier or long-form name.
As to age 65, this “retire to NZ” thing is looking better & better. 
Assuming of course that between now and then NZ hasn’t completely closed their borders to all Americans due to the shenanigans of my idjit countrymen. 
You’d be welcome of course, but your country needs moderate free thinkers like you to help hold the place together.
I believe part of this plan is that new waypoint names are to be selected from an ICAO list. This is very sensible but will see some humorous waypoints phased out. There used to be a string of waypoints along the Melbourne and Brisbane FIR boundaries in Australia that read something like: PUDYA SWEED LIPPS ALIDL CLOZA TOUDA PHONE.
This is not true for the Delta Airlines flights I’ve taken to/from Japan; the flight track accurately indicates where the aircraft has been, including clear depictions of points where they had made step-changes in heading (i.e. the track wasn’t just one big smooth arc that the seatback system had laid in the wrong place on the map). That’s how I knew that it deviated from the GC route.
Just a bit of an incidental side comment that flight tracking through sites like FlightAware can get pretty wonky when the flight path radically differs from what the system is expecting. Most of the information I believe comes from ADS-B transmissions from the aircraft to ground stations, some of which are even privately operated by hobbyists who upload the data to sites like FlightAware, but I think most are associated with airports and ATC centers.
A few years ago, for example, I read this heartwarming story about an Air Canada overseas flight (AC85) being diverted to save a dog on board when the heating system in the cargo hold failed. Originally scheduled to fly Tel Aviv to Toronto, it diverted to Frankfurt. The dog was transferred to another flight, and AC85 continued from Frankfurt about an hour and 15 minutes later:
I use FlightAware a lot and I was curious to see how it handled this very unusual routing. And the answer was: it got thoroughly confused! It showed the flight more or less on course along the expected route, until the flight diverted. At that point it did NOT show the diversion to Frankfurt. It just simply stopped reporting, as if the flight had vanished into thin air. And then a little over an hour later it showed a new AC85 originating in Frankfurt, as a completely new flight. That one then tracked normally.
So the information it displays is some combination of expected route, flight plan filed, and the ADS-B en route transmissions, all munged together in FlightAware’s algorithms.
Question for the pilots here. Where do those waypoint names come from? Unlike the ICAO or IATA airport codes, which are very systematic, they seem like whimsical character strings that make no sense!
Sounds more like a dog-warming story.
LOL! 