Airlines vs. General Aviation

 

Airliners Vs. GA Airplanes at the Airport

By Eric Stearns

Prerequisites
This lesson presumes a basic understanding of AirportDiagrams and basic taxi procedures. These subjects are covered in the lessons titled "Airport Diagrams" and "Ramps, Taxiways, and Runways".

Introduction
Airliners and small G.A. aircraft regularly operate simultaneously at airports around the world. The difference in performance between these aircraft creates some special considerations for pilots in these operations. Also, airliners and G.A. normally mix at busy airports with complex layouts which make flying more challenging (and fun).
When you operate at a busy airport, especially during an event, make sure you come prepared. This should start with a review of the airport diagram. Airport diagrams can be found by following the charts link on the PRC Index page; start by locating the region, then the airport, and then find the chart titled "Airport." (See StartUpAtAirport) When you examine the airport diagram, the first consideration is where you should position your flight simulator when you connect to the network. As you'll hear repeatedly, make sure it's not on a runway or taxiway! G.A. aircraft will never begin flights from a gate; there's no VATSIM rule against it, but if you plan to simulate reality, pick a starting place that is on a ramp away from the terminal. Some airport diagrams will depict general aviation parking areas.

Ground Operations - Departure
Depicted below is the layout of Los Angeles Airport (click on the image to view the complete airport diagram). Let's discuss what makes it complex and some strategies for successful operation at the airport.

After you receive your clearance, the controller should advise you which runway to expect for departure. If there's little traffic, that runway will probably be the one closest to your starting position; if it's an event with lots of traffic, you might get a runway that's based on your direction of departure, even if it's a great distance from your starting spot. At LAX, G.A. aircraft normally park on the south side of the airport, near the intersection of taxiways A and A5 (on the full diagram there's actually an arrow showing where general aviation parking is located). Let's say you start at G.A. parking and, after you get your clearance, the controller advises that you should expect runway 24L. Take a few minutes and study the possible taxi routes you might get. Note that you will have to cross two other runways to get to runway 24L. It's pretty obvious that there are numerous taxiways; ideally, when you call ground, you'll have the airport diagram in front of you and a pen to write down any complicated clearances. When you call, you might get a clearance as simple as "taxi to runway 24L"; in the U.S., this clearance would permit you to taxi via any route you desire and cross any runways (except 24L) along the way. Most other countries in the world require a specific clearance to cross a runway; so in those cases, "taxi to runway 24L" would still require specific clearances to cross 25L and 25R. Know the procedures for the country in which you'll operate, and if you're ever in doubt ask the controller for clarification. More likely, if it's busy, you'll get a taxi route assigned by the controller. During these busy times, the ground controller might ask you to follow other aircraft or yield to other aircraft while you taxi to your runway; if you don't see these aircraft, let the controller know and you will be given alternate instructions.

Ground Operations - Arrival
On arrival, as part of your setup for an approach, review the airport diagram. Using LAX as an example again, note that it has four parallel runways. At airports like this, it's easy to confuse runways, so take the time to familiarize yourself with the layout. Like on departure, arrivals may have to cross runways to get to their parking area. When you exit your landing runway, make sure you hold short of any other runways until you get a clearance to cross. Finally, by taking the time to review the taxiways as part of your preparation for an approach, you will be prepared should you get a complex taxi route after landing.

Differences between MSFS and real world airport layouts
It is very common to see differences between the airport diagram and the layout depicted in MSFS or X-Plane. Controllers should be aware of most of these differences, and taxi instructions should reflect the layout you see in your flight simulator. However, you might encounter a problem with taxi instructions occasionally. If you do, inform the controller and seek alternate instructions.

Wake Turbulence
As airplanes fly, they leave an air vortex behind them. The vortex is caused by the air pressure difference between the air above the wing and the air below the wing. This phenomenon is referred to as "wake turbulence". It can have violent effects on trailing airplanes; this is especially true if the trailing airplane is significantly smaller than the leading airplane. More information on wake turbulence is available from the United States' FAA publication called the Airman's Information Manual∞.

Even though wake turbulence is not modeled in the standard version of MSFS, controllers will simulate that it exists. When you depart behind a heavy aircraft, you should expect a delay for the wake turbulence to subside. When arriving behind a heavy aircraft, you should expect the controller to provide added spacing to protect against a wake turbulence encounter. In some cases, the added spacing required for departures and arrivals can be waived by the pilot; however, the rules on this vary between countries.

Accommodating performance differences
When G.A. aircraft operate in close proximity to airliners, the difference in performance creates special considerations. Some airports have separate runways for lower performance aircraft. Those that don't will provide extra spacing to compensate for the speed difference. On departure, a lower performance aircraft might be assigned a heading to move it out of the path of the better performing aircraft behind it. On departure, if you're assigned a heading that seems different than what the other aircraft are getting, this might be why. Fort Lauderdale Hollywood International is an example of an airport that has a runway (9R) used almost exclusively for GA traffic, which expedites arrivals and departures at a very busy airport:

Practice
To better understand how airliners and G.A. aircraft interact and to learn about complex airport operations, listen to live ATC for different large airports around the world at liveatc.net∞. Use the PRC link to charts from around the world to find an airport diagram for the airport(s) you listen to. You can also connect to the Vatsim network and monitor communications at an airport you'd like to fly out of. The controllers online should be friendly and happy to answer any questions as traffic levels permit. As a courtesy, be sure to file a flightplan even if you're just observing. Use the observing airport in both the departure and arrival boxes, then add "NEWBIE - Observing" to the comments section.


See VATSIM Forum comments http://forums.vatsim.net/viewtopic.php?t=5474