Clearance Delivery — IFR Clearances Last updated: 2017-07-10

The majority of the questions on this test relate to IFR clearances. An IFR clearance is an authorization for an aircraft to operate in the IFR System. The 5 critical parts of an IFR clearance are easily remembered using the acronym CRAFT, which stands for Clearance Limit, Route, Altitude, Frequency, and Transponder.

1. Clearance Limit ('C' in 'CRAFT')

Every time an IFR clearance is issued, it will contain certain items, issued to the pilot in a certain order. While these items and the order they are issued in is discussed above, we will go into a little detail about Clearance Limit itself.

Clearance Limit. It is exactly what it stands for. The limit of the IFR clearance, beyond which pilot cannot fly IMC, unless he either receives further clearance, or chooses to terminate his IFR flight plan. This limit, as you will learn while working Clearance Delivery position, is often the aircraft's destination airport. However at times this may be a fix, VOR, etc. For a large portion of your controlling Clearance Delivery, you will only be dealing with the destination airports as clearance limits.


1. "American Twelve Heavy, cleared to Chicago O'Hare international airport, ORCKA2 departure, LAS transition, then as filed, climb via SID except maintain five thousand, expect flight level three seven zero, five minutes after departure, departure frequency one two four point three, squawk one zero four two."

In this example, the clearance limit is Chicago O'Hare international airport(KORD). The plane is flying there anyhow, so unless his clearance limit is changed enroute for some reason, he can comfortably fly all the way...with the help of ATC naturally.

2. "Saratoga one five one, cleared to Las Vegas McCarran international airport, ORCKA2 departure, MISEN transition, then as filed, climb via SID except maintain five thousand, expect flight level two three zero, five minutes after departure, departure frequency one two four point three, squawk one zero three six."

In this example, the clearance limit is Las Vegas McCarran international airport(KLAS). Same applies to him/her, as to the plane in the first example.

  • Note: Airports should be pronounced using their correct name or city name to the extent possible. The ZLA Info Tool and are good places to find an airport name if you do not know it. Always include the word "airport" after the name of the airport.

Looking onto clearance limits where the limit is not the destination airport. Most of such cases exist in terminal or en route environment, where an aircraft would be put into a holding pattern, for any number of reasons. One of the very few reasons that Clearance Delivery would have to clear a plane to a clearance limit other than the destination airport, is if the plane was only departing IFR, and intended to continue the remainder of his journey under VFR. This may be for any one number of reasons(eg. IMC weather at departure airport, chance to depart faster under IFR than VFR due to other traffic loads, etc). The clearance would follow exactly the same format.

Example: "Mooney three six eight Mike Juliet, cleared to Paradise VOR , Seal Beach Eight departure, Sealbeach VOR, Victor Eight, Paradise VOR, climb via SID except maintain five thousand, departure frequency one two four point three, squawk one zero two five."

Final note

One important thing to remember to check for when issuing IFR clearances, is that the destination, be it an airport or not, corresponds to where the pilot is requesting the clearance to. It is quite easy and simple for the pilot to misfile, by either swapping the departure and destination fields or by misspelling the destination's code, etc. This doesn't become as much of a problem if the pilot asks for "Tower Enroute" to a destination, without filing.

2. Route ('R' in 'CRAFT')

The pilot chooses an optimum route when he/she files a flight plan. Our goal as controllers is to issue a clearance that is close to that optimum route; but, that also manages traffic flow and controller workload. That last consideration makes the route of an aircraft is the most important part of the clearance delivery process. Aircraft need to be on certain routes in order for our airspace, and letters of agreements with other ARTCCs to work. In actual operation, any route may be coordinated with the appropriate radar controller, and issued to the pilot if that controller agrees. However, for this test, all routes issued must comply with our SOPs.

2-1. Initial Routing Requirements

Because the airspace around our major airports can be quite busy, the route an aircraft takes immediately after departure is the most critical part of the clearance. At SAN, the main airport included in the clearance delivery exam, the initial route will normally be a SID, or Standard Instrument Departure.

SAN is a pretty straight-forward airport, as there are only a small number of SIDs to choose from.  At our larger airports, such as LAX, things are a lot more complex because it has several times the number of SIDs as an airport like SAN.

Some pilots will not have SID charts and will not be able to accept a clearance via a SID. In that case, assign the pilot an initial heading to fly (from the appropriate SID chart), for vectors to a route that mimics the SID.

For example, a pilot who should be issued the VTU8 departure, RZS transition, but doesn't have the chart, should be issued a clearance like "November four zero five hotel tango, cleared to San Francisco International Airport, via fly heading two five zero, radar vectors to Ventura, direct San Marcus, then as filed..."

A pilot who should be issued the LOOP1 departure, DAG transition, but doesn't have the chart should be issued a clearance like "November three zero three zulu sierra, cleared to Saint George airport, via fly heading two three five, vectors to Los Angeles, direct Daggett, then as filed..."

2-2. Routes to Destinations within ZLA

Aircraft requesting clearances to civil class B or C airports within ZLA are required to be issued the preferred route for the city pair. Preferred routes between some of our major airports can be found in the Required Internal Routes SOP. Many of them are also TEC routes, which are discussed in the next section.

Aircraft requesting clearances to ZLA military class B or C airports, or any class D, E, or G airport within ZLA need only be issued a route that comply with other SOPs (all of these requirements are discussed in this study guide).

For example, an aircraft requesting clearance to LAS must be issued the preferred route listed in the Required Internal Routes SOP. A jet departing LAX for LAS must be routed via MISEN, then the KEPEC STAR, or via DAG, then the CLARR STAR.

Even though simroutes lists a route for LAX-GCN, an aircraft requesting clearance from LAX to GCN has more route flexibility (since GCN is a class D airport). Its route need only comply with section 2-2 above. So, its initial route must be a SID with an approved transition point. Ensure these aircraft have a SID in their cleared route. A number of SIDs will work; in west ops, these include the HOLTZ, LOOP, LAXX, ORCKA, OSHNN, or DOTSS departures.

TEC Routes

The FAA has created a set of routes to be used for aircraft flying between most Southern California airports. These are called Tower Enroute Control (TEC) routes. These may be found in the Airport/Facility Directory (available at this FAA page), the ZLA Info Tool, or by selecting the TEC Routes link on the ZLA home page.

The TEC routes are broken down into aircraft classes. "J" class routes are for jets, "M" class routes are for turboprops, and "P" or "Q" class routes are for piston powered aircraft. If you are unsure what aircraft class a certain type is, refer to the ZLA Info Tool referenced above. Almost every aircraft type is listed in the ZLA Info Tool with the correct TEC class.

TEC routes include a cruise altitude. The clearance issued should ensure the pilot is assigned an "expect" altitude appropriate for the TEC route (i.e. "expect niner thousand five minutes after departure").

Aircraft are required to be routed via a TEC route if one is available. Exceptions must be coordinated with the appropriate radar controller, if online. For the test, always issue the appropriate TEC route.

The initial route out of SAN should be a SID that will connect the pilot with the TEC route. Many of the SAN TEC routes route aircraft via the Mission Bay VOR 293 Radial, then the Seal Beach 148 Radial to Seal Beach.  In this instance, the PEBLE or CWARD (if the aircraft is RNAV-capable) departures can be used to get the aircraft to SLI.  Aircraft routed over LAX can be issued the LAX transition of the CWARD departure.

TEC routes all have coded names for ease of filing. For example, the route from LAX-SAN during normal ops for a Jet has the code LAXN11. Aircraft may file this code in lieu of the whole route.  TEC Routes must, however, be expanded in the aircraft's VATSIM flight plan prior to being handed to the ground controller.  When issuing a clearance via a TEC Route, say the name of the first three letters in the route (for example, BUR would be Burbank, SAN would be San Diego, SCT is Socal, and CST is Coast), November, then the numbered identifier, then "routing".  Here are some examples:

  • SANN4 would be said as "San Diego November four routing"
  • LAXN51 would be said as "Los Angeles November fifty-one routing"
  • SANN4R would be said as "San Diego November four Romeo routing"
  • CSTN7 would be said as "Coast November seven routing"

Note- A special feature of the TEC system is that pilots do NOT have to file a flightplan in order to receive a clearance. Pilots asking to use this feature often will call up for "tower enroute" to a particular destination airport. Aircraft using this method need to have a flight strip created for them when controlling, but otherwise are handled like any other aircraft

2-3. Destinations Outside of ZLA for which we have Letters of Agreement (ZOA, ZLC, ZDV, and ZAB)

To facilitate movement of aircraft between ZLA and our neighboring ARTCCs, we have agreed to ensure that aircraft are issued certain STARs in their routes. The clearance delivery controller is responsible for ensuring that the clearance he/she issues complies with the Letters of Agreement we have with our neighbors. These LOAs are available on the ZLA website using the "Documents" link.

For example, our LOA with ZAB ARTCC requires that an aircraft departing LAX for PHX crusing above FL240 be routed via BLH and then either the HYDRR or ARLIN STAR. The clearance delivery controller is responsible for ensuring that the routing by which the aircraft is cleared complies with this requirement.

Our LOA with ZOA ARTCC requires different STARs for SFO, OAK, and SJC depending on the runway configuration in use at those airports. You can determine the runway in use by contacting the LAX_CTR controller or one of the ZOA controllers. For example, when landing west, SFO requires a routing via SERFR, then the SERFR2 arrival.  When landing east, aircraft are required to be routed via SERFR, then the WWAVS1 arrival.  If the test does not specify a configuration for SJC/OAK/SFO, presume that they are using west operations.

The route issued to aircraft covered by our LOAs only needs to comply with the LOA prescribed routing and the initial routing requirements discussed in section 2-2-1 above. For example, an aircraft requesting clearance between LAX and DEN need only fly a SID (based on section 2-2 above) and the POWDR STAR to DEN (based on our LOA with ZDV). A number of routes could comply with these requirements. The pilot could be cleared via ORCKA2 LAS TBC HBU POWDR8, or DOTSS2 CNERY EED TBC HBU POWDR8, or any other route combination that complies with the initial routing requirements and our LOA with ZDV.

Review each of the LOAs so that you are prepared to issue the correct routing to aircraft. Ensure that each of your test answers complies with all LOA provisions.

2-4. Destinations Outside of ZLA for which we have no agreements

If an aircraft requests a clearance to an airport outside ZLA, for which we have no LOA, any routing is acceptable so long as you comply with the other routing SOPs. For example, an aircraft requesting a clearance between LAX and JFK has a large range of routing choices. The only requirement for the clearance is that the pilot be cleared via an appropriate SID. LADYJ2 CSTRO, ORCKA2 MISEN, DOTSS2 CNERY, or PNDAH2 TCATE would all be acceptable (as would any other SID that's appropriate for the direction of departures at LAX).

2-5. Summary

This section provides a "checklist" for examining a route. If you follow these guidelines when evaluating a route, you will always end up issuing a route that complies with all requirements.

When you examine the route filed by a pilot, first determine if the destination airport is covered by a TEC route. If the destination airport is covered by a TEC route, issue a clearance via the routing given in the TEC route, and ensure the pilot is assigned the cruise altitude given for the TEC route.

If the destination airport is not covered by a TEC route, then determine if the destination is a civilian class B or C airport within ZLA. If it is, issue an appropriate route from the Required Internal Routes SOP, if applicable. The cruise altitude need only be correct for direction of flight (see the next section for more).

If the destination airport is not covered by a TEC route and is not a ZLA civilian class B/C airport, then determine if it is covered by an LOA with one of our neighbors. If it is covered by an LOA, then issue a route that complies with the LOA and also ensures that the route includes a SID or mimics a SID (as discussed in 2-2 above). A few of our LOAs specify a maximum cruise altitude, or assign different procedures depending on the final altitude of the aircraft; ensure these requirements are met in your clearance.

If the destination airport is not covered by a TEC route, is not a civilian class B/C airport, and is not covered by an LOA, then any route is acceptable, so long as the aircraft is issued a SID or a route that mimics a SID.

As was stated at the beginning of this section, the goal of this process is to clear a pilot by a route that is close to (or the same as) his filed optimum route. Only issue changes to the pilot's route that are needed to comply with our SOPs.

2-6. Phraseology and Miscellaneous

2-6-1. SIDs and STARS

Certain SIDS and STARS are pronounceable, as evidenced by the name of the departure procedure in the top left portion of the chart. For example, the VNY3 departure out of BUR is pronounced is pronounced on the radio as the Van Nuys Three Departure. On the other hand, the ELMOO8 departure is pronounced ELMOO Eight Departure. The easy way to check for this is to read the name of the procedure in the top left portion of the chart. For this test, use the name of the departure procedure on the top left side in your answer.

2-6-2. Reading Routes

If no changes are required in a route, and a SID/Transition is not being used, clear the aircraft "as filed".

"American One Twenty Three, cleared to Grand Canyon Airport as filed."

If no changes are required in a route, and a SID is being used, but not a transition, then say the name of the departure, followed by "then as filed."

"Skywest Sixty Fifty-Two, cleared to Palm Springs Airport, Seal Beach Eight Departure, then as filed."

  • Note: Transitions are not the same as exit fixes, but are small route segments published on a departure procedure. For example, the LAXX1 departure has a TRM transition, but not a SLI one. This is easily seen by reading the bottom of a departure plate in the narrative section.  All transitions will be listed there.

If no changes are required in a route, but a SID and Transition are being used, then say the name of the departure, name of the transition, followed by "then as filed".

"Delta Seventy Four, cleared to Atlanta Hartsfield Airport, DOTSS2 departure, CNERY Transition, then as filed."

Note:  Even though the routes of these aircraft were fine, you still must always explicitly issue a SID and Transition if they are intended to be used.

Aircraft filing a TEC route by its Coded Name need not be read the SID and Transition if this information is explicitly included in the TEC route, and are cleared via the name of the TEC route, such as "American Six, cleared to Los Angeles International Airport via the San Diego November Four Romeo routing"

If changes are required in a route, then read a Full Route Clearance to the point where the filed route meets up with the assigned route. If there is not one, and the route does not end with a STAR, and the clearance limit is an airport, then end with the word "direct", to signify that the airport is the end of the route. There is no formula to reading a full route clearance, but the following tips are helpful:

-Aircraft "join" an airway and "intercept" localizers and a radials. Radials are most commonly seen in TEC routes. If you see something like MZB320R, that means Mission Bay 320 Radial.

-Low altitude airways are pronounced by the word Victor, and the numbers of the airway in group form, for example "Victor Two Thirty-One", while High altitude airways are pronounced the same way except with "Jay" in front.

2-6-3. Equipment Suffixes

If assigning a route, remember that certain aircraft are limited to navigating via VORs and radials, while other aircraft can go direct to places(RNAV/GPS type equipment). Try not to assign routings that are outside the aircrafts capabilities, and never assign a SID/STAR that a pilot cannot fly because his equipment does not allow it.

3. Altitude ('A' in 'CRAFT')

Just like with the clearance limit, each IFR clearance needs to have altitude information included. This is imperative for a number of reasons. Pilots need to know how high and at what time they can climb after departure. This is generally done by assigning the pilot an initial top altitude and then giving him the time or place when/where he can expect higher. As with many ATC instructions, much of the altitude information exists so that in the event of lost communications, pilots know how to proceed with their flight.

The inclusion of "climb via" instructions at the clearance delivery level has changed the way altitudes are assigned by ATC. This instruction must be included for departures on a standard instrument departure (SID) with any altitude or speed restrictions.

3-1. Standard Instrument Departures with Speed or Altitude Restrictions

In this case, "climb via" phraseology must be used so that pilots meet any charted restrictions during climbout. If the top altitude is listed in the procedure description, then no further information is required. The final altitude can be omitted unless an amendment is required.

"United Seven Ninety Three...climb via SID..."

If the top altitude is not listed in the procedure description or needs to be modified for any reason, then "except maintain" should be used to change the top altitude.  The correct initial altitude assignments can be found located in the ZLA Initial Altitude Assignments SOP.  The final altitude can be omitted unless an amendment is required.

"United Seven Ninety Three...climb via SID except maintain five thousand..."

3-2. Standard Instrument Departures without Speed or Altitude Restrictions

"Climb via" does not apply to these departures because they have no restrictions that must be met. In this case, an initial altitude must be assigned to departing aircraft. The final altitude must be assigned afterwards.

"Climb via" should also not be used for procedures with published top altitudes and/or published speed and altitude restrictions if a radar vectored segment with no altitude restrictions is published prior to an aircraft joining a route.  An example of this is the SLAPP departure out of BUR, where aircraft are radar vectored to RAYVE, then join a route with published altitude restrictions.  At LAX, the ORCKA departure, despite having a radar vector segment to reach KLIPR, would still use "climb via" phraseology as there are published crossing restrictions at FABRA, DLREY, DOCKR, and HIIPR prior to the radar vector segment.

Use "maintain (altitude)" to assign an initial altitude.

"United Seven Ninety Three...maintain 5000..."

3-3. Aircraft Without a SID

"Climb via" does not apply to departures without a SID. These aircraft should be assigned an initial altitude to maintain after departure. The final altitude must be assigned afterwards.

"United Seven Ninety Three...maintain 5000..."

3-4. Final Altitude

Most final altitudes for clearances follow the NEodd/SWeven rule.

Before getting into the flight direction rules it's probably a good idea to go over a few basic terms that every controller should know that pertain to altitudes and pressure.

  • Altitude - The vertical position of an aircraft (or object) above Mean Sea Level (MSL).

  • Flight Level - A standard nominal altitude (usually vertical) of an aircraft, referenced to a world-wide fixed pressure datum. In the United States a Flight Level starts at 18,000 MSL because the Transition Altitude starts at 18,000 ft.

  • Transition Altitude - The highest altitude at which an aircraft in normal operation should use an altimeter pressure setting indicating height above mean sea level (QNH).

  • Transition Level - The lowest flight level available for use above the transition altitude.

  • Transition Layer - The airspace between the transition altitude and the transition level.

To ensure safe separations between aircraft above the transition level, flight levels have been allocated to aircraft according to their direction of flight. This is the semi-circular cruising level system also known as the NEODD-SWEVEN Rule.

NEODD - Aircraft flying North or East (0 to 179 MAGNETIC COURSE) will be issued odd altitudes up to and including FL410. Above FL410 aircraft will still be given odd altitudes yet at intervals of 4000 ft (i.e. FL450, FL490, FL530).

SWEVEN - Aircraft flying South or West (180 to 359 MAGNETIC COURSE) will be issued even altitudes up to and including FL400. Above FL400 aircraft will be given odd altitudes yet at intervals of 4000 ft beginning at FL430 (i.e. FL470, FL510, FL550)

Note: Remember that TEC routes also have altitude assignments that go along with them. These are MANDATORY to assign, and may or may not comply with the rules above.

Note: You should normally assigned the altitude the pilot requests for his final altitude, unless that altitude fails to comply with the above rules. If it does not, pick a reasonable altitude as close as possible to the one the pilot requested.

Note: Although in real life aircraft need to be RVSM qualified to operate between above FL290, as indicated by the equipment suffix, on VATSIM all aircraft are considered RVSM qualified, and regardless of equipment suffix may cruise in RVSM airspace.

Hint: In general, airports in ZOA and ZSE(Oakland and Seattle ARTCCs) are west of our airports, while most other airports are east. Assign altitudes appropriately.

Pronounce Altitudes below 18000' by stating the numbers in front of the comma in individual form, followed by the word "thousand", and the numbers after it in group form. If the numbers after the comma are all zeros, then end on "thousand". Aircraft should be told to expect their final altitude 5 minutes after departure. For example;

Example: "November Seven Two One Sierra Papa...expect One Three Thousand five minutes after departure". "Skywest Seven Ninety Four...expect Seven Thousand five minutes after departure".

Pronounce altitudes above 18000' by stating "Flight Level", followed by the the first three digits of the altitude, in individual form.

Example: "American Six Sixteen....expect Flight Level Two Four Zero Five Minutes after departure."

4. Departure Frequency ('F' in 'CRAFT')

The Departure Frequency for an airport is the frequency of the controller that will work the aircraft immediately after takeoff. At SAN when fully sectorized, this sector will be SAN_W_APP, on 119.6.  When we are not fully sectorized, it is your responsibility to ensure that you are aware of the controller currently working departures from the airport you are clearing. For the purposes of this test, you can assume that we are fully sectorized. In each clearance, you must inform the pilot of the frequency of the departure controller, as follows.

"American One Twenty Three..., departure frequency one two four point three"
"Delta Zero Seven Six..., departure frequency one three four point two"

5. Transponder Code ('T' in 'CRAFT')

The Squawk Code is normally assigned using the F9/Assign Squawk Command in VRC. For the purposes of this test, if a squawk code is not assigned in the question, you may use any reasonable squawk code. Remember that squawk codes use only the numbers 0-7 inclusive, so there will not be squawk codes such as "9871". Squawk codes are read out by pronouncing each number individually, as follows:

"Seneca Eight Seven Delta Romeo..., squawk one zero six four."
"Express Jet Six Forty..., squawk seven six five four."

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