Making Some Sense of Flight Routes
The misses is on a flight to Suriname, so I’m tracking her flight in an online flight tracker while she is enroute.
The flight routes for commercial flights are obviously indicative of the journey the aircraft will be venturing through the skies and I just got curious which led to a full day of entertainment.
The flight plan I ran into looked like this…
GORLO UL980 LAM UL179 CPT UM197 GAPLI GUNSO OMOKO 4800N 01500W 4500N 02000W 4200N 02500W 3900N 03000W 3500N 03700W 2900N 04500W 2300N 05000W 1800N 05200W 1400N 05300W 0916N 05400W ZY
The funk does that mean?!? :confused:
Since we are leaving from our starting airport we will need to understand what GORLO really means. GORLO is one of the departure routes available from Schiphol (EHAM). This stuff is thoroughly documented in Aeronautical Information Publications (AIP) released by the national aerospace authorities. The documentation for Schiphol (EHAM) contains the following descriptions for GORLO departures:
- GORLO 2F (from runway 4)
- GORLO 2N (from runway 9)
- GORLO 1P (from runway 27)
- GORLO 3V (from runway 36L)
- GORLO 1Z (from runway 36L)
In total there are five ways to start a GORLO departure. Any one following a GORLO departure instruction from its designated take-off runway should end up heading the same direction eventually.
I chose to take a look at GORLO 2N (runway 9) and got the following take-off route description:
Track 087° MAG. At 500 ft AMSL turn left (turn MAX 220 KIAS) to track 315° MAG. At 7.0 SPL turn left to track 271° MAG. At 11.0 SPY turn left to track 212° MAG to intercept SPY 242 to VOLLA (29.0 SPY). Track 238° MAG to GORLO (72.3 SPY). RNAV: THR 09 / At 500 ft AMSL turn left / EH053 (MAX 220 KIAS) / EH094 / EH090 / EH091 / VOLLA / GORLO
Backed up by the map below, my interpretation of the sequence of relevant waypoints and the RNAV is…
Maintain the 087° heading until 500 ft above medium sea level, at which we turn to follow a heading of 315°. At 7.0 nautical miles to the SPL VOR we turn left to track a heading of 271°. At 11 nautical miles from SPY we turn again to track a heading of 212°. We are to intercept SPY 242 to the VOLLA waypoint which is 29 nautical miles from the SPY VOR. Once there we slightly change our heading to 238° and set course for the GORLO waypoint.
The RNAV line simply contains the lift-off runway, directions for the left turn after take-off and the waypoints we have to cross on our way to GORLO.
Very High Frequency Omni-direction Radio range navigation allows the observer to obtain the heading and distance information (in the case of VOR-DME’s). It is simply a beacon. As such it may be the case that the VOR is not necessarily used just to be flown over but to obtain the proper heading for a intended route in relation to a fixed point on the earth surface. Generally VOR’s are designated with three letters. In the flight route displayed at the beginning of this post LAM and CPT would be VOR’s beacons that we tune into to establish the proper heading.
Now that we’ve unraveled the departure mystery we get the U980 which is an airway. Airway designations in Europe contain one letter, where the letter U is used to indicate high enroute traffic, followed by one to three numbers. In the US, airways are prefixed with the letters V (low altitude based on VOR), J (high altitude based on VOR), T (low altitudes RNAV) or Q (high altitude RNAV).
The five-letter words in the flight plan that are not known as departure or arrival routes are known as waypoints. During the flight the aircraft will fly-over or fly-by GAPLI, GUNZO, and OMOKO in the listed order. These waypoints and the corresponding GPS coordinates are available on OpenNav.
Out on the open sea waypoints are not named which seems quite obvious as I can not imagine the convenience of assigning a proper name to every waypoint on the ocean. The convention here is to use the latitude and longitude of the location in designating the waypoint. A waypoint designated as 4500N 02000W would simply be the waypoint located at 45°N 20°W.
I got my hands on aeronautical charts for the destination which choreograph the approach dance for a ILS landing. The ILS approach is only possible when landing at a heading of 11 which I believe is assigned based on the direction of the wind at the time of landing as we will most likely land into the wind to maintain a proper airspeed. If we land on a runway 29 (which is exactly the same tarmac runway, only approached from the other side) we will need to execute a VOR-DME approach, which has been nicely explained in a FlightGear tutorial I found on youtube.
On the map we have our frequencies, approach patterns and corresponding airspeeds and altitudes, which should be enough to keep the process moving forward.
Yet again, a FlightGear How-to video comes to the rescue by quickly explaining some of the concepts encountered in this map.
My summary of the ILS approach, assuming we are approaching the ZY VOR-DME at a heading of 227°, would be…
Maintain a heading of 227° to the ZY VOR and turn right to heading 309° when at 2 nautical miles from the VOR (we are assuming we are a in a heavy airliner which would most likely qualify as CAT D). Whilst flying the assigned heading. At 9 nautical miles from ZY we start the turnaround to heading 106° to line up with our runway. This maneouver should be executed at an altitude of 2000 feet. Whilst on the 106° radial we initiate the 3° descent using the recommended descent rates for our given airspeed. The approach plate indicates a descent of 372 fpm (feet-per-minute) at 70 knots till 849 fpm at 160 knots. At a half nautical mile to the VOR we approach the middle marker, before that point we should have established visual contact with the cues available on and near the airstrip, otherwise we are set to fly a missed approach.
The misses has already landed :airplane:… time to sleep.