JHB Flight Packs
Flight Plan decoding
What is a flight plan?
The new Flight Packs page provides a good selection of schedule or charter flights from Ronaldsway and Liverpool. For each flight I have provided details from the real flight plans so you can emulate the flight more accurately.
In addition to the aircraft type, speed (TAS) and requested flight level I have also included the full airways route provided by the flight plan. I have not pulled any punches here and the routes shown are reproduced exactly as submitted in each flight plan.
To help in your understanding of the route format I think it would be useful if I provided a crash course in real world flight plan layout. Taking one out of the hat completely at random we shall look at JHB426E from Liverpool to Bodrum in Turkey. The actual flight plan sent by the company to the ATC computer system is shown below (altered only to remove the original company identity):
-N0459F330 STOCK L975 OTR UY70 BLUFA UL603 PAM UL620 NARKA UL618 MOKRU UL606 EKI/N0459F370 VG80 OKESA VG80 AKBUK
-LTFE0349 LTBS LTBJ
-EET/EHAA0033 EDVV0051 EDUU0107 EDBB0111 LKAA0124 LZBB0146 LHCC0155 LRBB0208 LBSR0239 LTBB0255 REG/GXXXX SEL/FGHI OPR/JHB COM/TCAS DOF/010625 SRC/RQP RVR/75
If you have used IVAO, FSNav or similar planning software you may be able pick most of the above up but I'll provide a line by line decode below.
All of this should be quite easy to understand (the important bits anyway) so let us take a more detailed look at the route field. This was:
STOCK L975 OTR UY70 BLUFA UL603 PAM UL620 NARKA UL618 MOKRU UL606 EKI/N0459F370 VG80 OKESA VG80 AKBUK
Before we dive in I have to mention a little about airways routes in Europe because you are going to get confused. It's not your fault - things are changing rapidly in the real world and FS data is lagging behind..
Changes in the European Airways System
In the old days airways ran from navaid to navaid and it was uncommon for any airway segment to exceed the range of the VOR at either end of the leg. The flow of airways was therefore dictated by where each country decided to place their navaids - logically arranged at a country level but not so well designed for Europe as a whole.
As airspace became more overcrowded it was realised that the system was inefficient and that a new airways structure was necessary - one that produced a rational flow throughout Europe. No progress was made for some time as each country baulked at the expense of moving all their navaids!
With the introduction of FMS/GPS systems the realignment of the airways system became feasible at last - freeing the airways from the fixed navaids that had dictated the structure for so long. It also meant that airways could be any length as they were no longer limited by the transmission range of VOR's/NDB's.
The new European airways structure began implementation several years ago and it will take some time to complete. Not only are new airways being introduced but many old ones are being phased out or redesignated. As will be apparent a lot of the new airways don't go anywhere near a navaid and this has produced a rapid rise in the number of intersections/fixes now found on current charts. These are always shown as a five letter group so that WAL is obviously a navaid but BLUFA is a fix.
Some flight planning programs like FSNav are useful here as they contain most of the fixes found in real life - and are mostly up to date. FSNav also gives airways designations but here you do have to be more cautious as they are not always current. It is probable that you will see the airway you want but it may be under a completely different name.
A final point. The airways structure is becoming very much a one way system in Europe. That is why I include routes for both outbound and return flights on the page. You will see that very few return flights follow the same path as the outbound legs. This makes the flights all the more interesting!
Understanding Flight Plan Routes
Back to the flight plan now. The route field is a standard format in that it will show a navaid (or fix) followed by the airway being flown. Only when changing airways will the next navaid be put down - this then followed by the new airway.
Looking at the example plan from Liverpool to Bodrum the initial part of the route is shown as
STOCK L975 OTR UY70 BLUFA UL603 PAM UL620 NARKA.
The aircraft will fly the SID out of EGGP and end up at STOCK - then take up airway L975 to OTR. Although it will fly over fixes at UPTON and GOLES these do not have to be put in the plan because the aircraft is known to be on L975 - and will stay on it all the way to OTR.
OTR appears on the plan because this a the point at which the aircraft changes airway - on to UY70 - and so routes to BLUFA. It then changes airway again onto UL603 to PAM VOR. Quite straightforward but watch the next bit.
From PAM it takes up UL620 to the next fix at NARKA. This is a nice brief entry on the plan but this leg is over 700nm! Because the aircraft remains on UL620 all the way to NARKA the flight plan does not have to show any points between PAM and NARKA - even though the full route is PAM ARNEM REKEN VAMKA LINSI LEG HDO HLV SLC LITKU KOVEK and NARKA. Luckily UL620 shows on my copy on FSNav and it was a simple matter to trace it through from PAM to find the route above - faster than I could trace it on my charts! So, beware - a short route field on a plan may not reflect a short overall route!..
If any of you are using real world charts you will find the same problem with airways that plagues FSNav. Unless you have really up to date charts they may not show the airways you may be looking for. The airway UY70 shown above is a very recent addition - I admit that it is not on the charts I have here!
The rest of the route is:
UL618 MOKRU UL606 EKI/N0459F370 VG80 OKESA VG80 AKBUK
I will skip this bit as it follows the same pattern but you will notice that very few navaids are used - it is mostly a FMS/GPS route.
When you get to EKI you'll notice a different grouping on the plan - showing EKI/N0459F370. If you look back at the flight plan speed and level group at the beginning of line 4 it showed N0459F330 - indicating that the initial cruising level requested was FL330. By EKI the aircraft is lighter and at this point the aircraft is requesting a climb to FL370. You will see this on many of the plans, sometimes more than once, as aircraft aim for the optimum height as fuel is used up.
A further variation can be found on the flight plans to GCTS (Tenerife). Here, at OMOKO you will see OMOKO/M077F330. M077 shows that the aircraft now intends to fly at Mach 0.77 rather than the 470kts TAS previously shown. Mach cruise is a requirement when flying in certain regions of the world, the Atlantic being one of them, and the change is shown on the plan at the Oceanic entry point. The reverse happens when they leave the area - speed will change back to TAS. The autopilot in FS does indeed have a TAS/Mach option so it is quite a simple matter to imitate this flight plan alteration..
Finally, you may sometimes come across the code DCT in a flight plan. Don't start searching for a navaid by that code! DCT simply means DIRECT and is used when an aircraft wants to route from one point to another which is not along an airway - yes they can do this. An example would be OTR DCT NEW as no airway exists between OTR VOR and NEW VOR.
That wasn't so bad was it? If you spot any other oddities in the routes that confuse you then drop me an email.
There are other oddities.Any flights crossing Russian airspace get mighty odd as they require speed in KPH and heights in metres! You may very well see a flight plan start with N0420F330 and then change to K0779M100 as it crosses into Russian airspace!
John Woodside HC JHB