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In the answer to this question about why people use airways, one of the commentors pointed out that GA aircraft often use airways in a different fashion than commercial aircraft. I couldn't tell from context why this is true though. Is it laziness, spite, lack of knowledge? Or is it simply that GA aircraft are instructed to use them differently? Or, even, is it that GA aircraft are typically at a lower altitude so they simply have different airways?

Why do GA aircraft use airways different than large commercial planes?

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In Europe, some airways are only available in certain flight level ranges, so a commercial airliner and a GA turbo-prop travelling from the same departure airport to the same destination airport could be travelling on different routes due to airway restrictions in place and the inability of one aircraft to climb to the same level as the other. Below the routing for PC12 operating IFR at FL150 and an A320 operating at FL250.

(FPL-DEXAM-IG
-PC12/M-SDE1FGHIJ1RWXY/LB1
-EDDL1000
-N0160F150 KUMIK L603 KOSEK Z74 HAREM T104 ANORA
-EDDM0150 EDQT
-PBN/A1)

The above flightplan from EDDL to EDDM validates for FL240, but anything above FL245 will not pass, it will error out with:

PROF195: KUMIK L603 KOSEK DOES NOT EXIST IN FL RANGE F245..F999
PROF195: KOSEK Z74 HAREM DOES NOT EXIST IN FL RANGE F245..F999
PROF197: RS: EDUUFFM14 EDUUFUL13 EDUUNTM13 EDUUTGO13 EDUUSLN13 EDUUWUR14:F245..F255 IS CLOSED FOR CRUISING REF:[EUROED41A] ED AIP(ENR3.3 1 NOTE 9)

To fly the same flight in higher levels, you would need another routing:

(FPL-DAXAM-IG
-A320/M-SDE1FGHIJ1RWXY/LB1
-EDDL1000
-N0260F270 DODEN Y853 BOMBI T104 ANORA
-EDDM0150 EDQT
-PBN/A1)

This routing works fine for anything above FL245, below it would again error out with:

PROF195: BOMBI T104 HAREM DOES NOT EXIST IN FL RANGE F000..F245
PROF204: RS: TRAFFIC VIA DODEN Y853 BOMBI IS ON FORBIDDEN ROUTE REF:[ED2318A] Y853 DODEN BOMBI
PROF205: RS: TRAFFIC VIA DODEN Y853 BOMBI:F000..F245 IS OFF MANDATORY ROUTE REF:[ED2318B] Y853 DODEN BOMBI
ROUTE135: THE SID LIMIT IS EXCEEDED FOR AERODROME EDDL [EDDL50120A] CONNECTING TO DODEN
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  • $\begingroup$ As I understand it, Europe has much more stringent routing than in the US, although the routing along the East Coast of the US is also quite stringent. $\endgroup$ – rbp Jan 6 '15 at 15:52
  • $\begingroup$ Yup. I am doing this for fun basically, as I don't hold an IR on my PPL, I only use the proper routing in simulation. When you try doing routes by hand and validating them, you get frustrated after 5min, try another 5min and suddenly get the hang of it. I love it. Jay didn't tag his question with ICAO or FAA, so it's good to have both answers here on his question. :) $\endgroup$ – SentryRaven Jan 6 '15 at 15:54
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    $\begingroup$ instead of a TB20, you should file a PC12 or a TBM-800. the TB20 doesn't have the altitude capability or speed for FL240 $\endgroup$ – rbp Jan 6 '15 at 15:56
  • $\begingroup$ I changed it to the PC12. The FP for the GA aircraft is at FL150 N0160F150, I did only remark that the FP would validate up to FL240. $\endgroup$ – SentryRaven Jan 6 '15 at 15:59
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    $\begingroup$ US instrument routes have something similar (but not as complex as Europe): We have low-altitude airways - V (VOR) and T (GPS) - below 18,000 feet MSL, and high-altitude airways - J ("jet routes", based on VORs) and R (GPS) - above 18,000 feet MSL). $\endgroup$ – voretaq7 Jan 6 '15 at 16:36
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It depends on the type of aircraft, and the operational support behind the airplane.

In the Western US (as I would expect is also true for Les Alpes), the terrain is quite high, and there is sparse radio coverage at lower obstacle-clearing altitudes. Lighter aircraft will opt for Federal Airways, which have a Minimum Enroute Altitude that ensures obstacle clearance, and radio navigation aid and voice communications coverage.

Carriers have huge flight operations departments, which plan the routes taken by their aircraft. Since carriers have scores of flights in the air, they are constantly adjusting routes for traffic and weather, and may file routes that a smaller operator wouldn't consider

For smaller operations, there are "Preferred IFR Routes" published in the A/FD (see below). They can also obtain one-off or subscription flight operations from companies like Jeppesen, which give them the resources of a large flight operations department.

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There are variations in how particular airways are used, but there are not routes that are restricted based on the type of operation here in the US, or anywhere that I know of.

As others have pointed out, there may be various restrictions on an airway (route) such as altitude, times of use, directions of use, etc. but they apply the same to GA aircraft as a commercial aircraft.

Keep in mind that GA encompasses a wide variety of different types of aircraft, including aircraft that have far less and far more capabilities than commercial aircraft. Saying that a particular airway is restricted to aircraft flying above 18,000 feet does not restrict it to commercial aircraft, and the entire system is based on a first come first serve concept.

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