Document Information
Version 1
Created 01/01/2016 00:56
Last Updated 03/17/2023 17:29
by Matthew Woerly

Seattle-Tacoma International Airport Delivery

I. Purpose

This document is a guide to SEA_DEL procedures. This document does not supersede SOP_103, Seattle ATCT SOP. SOP_103 must be reviewed, this document is merely a resource.

This document assumes you have already studied the VATUSA S1 CBT: Please refer to those CBTs for more background and guidance about the Clearance Delivery ATC position.

Seattle Clearance Delivery shall operate under the call sign as SEA_DEL. The frequency to use is 128.000. Radio Callsign is "Seattle Clearance"

Note: This is not for real-world ATC training. It is intended for use by controllers in the VATSIM system.

II. Position Description

Provides weather briefings and VFR/IFR departure clearances. The DEL controller shall also coordinate with the Departure/Approach (APP) controller to issue the pilots the preferred routings. Clearance Delivery does not issue instructions to an aircraft that involves any movement. Once the clearance has been issued to the pilot then you instruct them to contact the Ground Controller or the next higher controller.

NOTE: In the absence of a SEA_DEL controller, the SEA_GND controller shall perform the duties contained within this document. If there is no SEA_GND controller, then SEA_TWR will perform these duties; and so on.

III. A Look at the Flight Strip

Below is a sample flight strip. The flight strip contains all of the necessary data for tracking the plane during its flight. As a Delivery Controller, it is extremely important to understand all the data in a flight strip. Mistakes here can be corrected here before the plane is airborne. If an error is not caught then the workload for other controllers down the line is affected. Perhaps a conflict could occur if not caught in time.

SEA Flight Strip Example


IV. Clearance

All VFR and IFR aircraft will need clearance to depart from KSEA. IFR always needs a clearance leaving from any airport, but VFR aircraft need clearance at KSEA because they will be operating in the Class B airspace around KSEA, at least for a little while. When issuing IFR clearances keep in mind the C.R.A.F.T. acronym.

  1. Clearance Limit - This is the farthest point along its route the aircraft may fly. Usually, this is the arrival airport. Note that it is not required for the pilot to select an alternative airport.
  2. Route - This is the route the aircraft will take to arrive at its destination. Usually, this will contain a SID (Standard Instrument Departure), transition (if assigned), fixes, or even the phrase direct.
  3. Altitude - This is the initial altitude for the aircraft. For Seattle-Tacoma, the initial altitude is  7,000ft. If not listed on the SID, pilots can expect the filed altitude 15 nautical miles after departure.
  4. Frequency - This is the frequency for Departure/Approach control, or if Departure/Approach is not on, then Center. The Departure/Approach controller will handle all departures and approaches and operates on a frequency of 125.600. Center is on 124.200.
  5. Transponder Code - This is the transponder code you assign the aircraft. Seattle ARTCC has a specific set of codes to use. See the separate document about which codes to use.

Remember when issuing squawk codes that the highest number is 7. There are no 8 or 9s in a transponder.


When issuing VFR Clearances at KSEA, the clearance is much simpler, because you don't need everything in the C.R.A.F.T. acronym. You just have to clear them to operate in the Class B airspace, remind them to maintain VFR at all times, and give them their squawk code. Keep in mind that on VATSIM the VFR pilots are not required to submit a flight plan. They simply need to advise ATC of their intentions.

V. Aircraft using Departure Procedures

(Formerly known as SID)

Each airport has its own designated departure procedures (DP or SID). They can be published charts or simple verbal instructions given by the controller. At the busiest fields, there will be Departure Procedures. A DP is a published departure that instructs a pilot on how to exit the terminal area. They were created to relieve the controller's workload. Some contain printed turns and some don't. Yet all provide obstacle clearances and transitions. A transition is a fix where the departure procedure ends and the pilot may proceed with the filed flight plan. There are three types of Departure Procedures:

  1. Pilot Nav - These are printed departure procedures of which the pilot is responsible for flying and proceeding toward the transition with minimal ATC instruction. For example, see Seattle's SUMMA departure.
  2. Vector - These are printed procedures of which the controller is responsible for vectoring the pilot to the transition. For example, see the Seattle Departure.
  3. Area Navigation (RNAV) - This is a special type of SID. The pilot is responsible for all navigation. The aircraft MUST be certified to fly this procedure. The aircraft must have GPS/Flight Management Computer on board to fly this departure. In the flight strip, the aircraft will have a /I, /Z, /G, or /L. An example of this SID is the HAROB departure.

Here at Seattle, we prefer to use Departure Procedures as much as possible. If the aircraft does not file one, issue the appropriate DP for the route of flight. When issuing clearance it is a good practice to have the departure charts printed out and within reach for quick reference.

If there is no other SID in the direction the aircraft is headed or if they cannot use an RNAV SID, they will need to use either the SEA or MONTN. How do you decide which one to use? The following flow chart explains the basic logic per SOP-103.

SEA vs. MONTN departures


VI. Aircraft Not Filing for the Departure Procedures (DP)

bad flight strip

If the aircraft files NO DP (or NO SIDs) in the comments or refuses to accept a Departure Procedure then they shall be cleared via the SEA 161 Radial or SEA 341 Radial depending on which runways are in use. (See examples later)


VII. Altitudes

The Clearance Delivery Controller is required to know the proper altitudes for the direction of flight. The general rule of thumb is NEODD and SWEVEN. Any altitude including and above 18000 MSL is called a Flight Level (FL).

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. FL, FL470, FL510)

FL180-410  East at ODD Altitudes / West EVEN Altitudes

FL430 West ... FL450 East ... FL470 West ... FL 490 East ... FL510 West ... FL 530 East ... FL550 West etc.                                                                                           


What counts for "north/eastbound" or "south/westbound" is the magnetic course when the plane is up at cruise altitude, which means you don't count the departure procedure if it goes the other way. For instance, the ELMAA8 DP starts out going west, but most routes then go southeast to California, etc., and by the time the plane is up at cruise altitude, it will be done going west and now is southeast-bound; so the specified cruise altitude should follow the north/eastbound rule.

You'll need to have an IFR en route chart available if you're not sure which magnetic course will be used. As a rule of thumb, every major airport in the lower 48 United States is East of KSEA, even Portland, and Eugene; CYVR (Vancouver) is west, as are all airports in Alaska and Hawaii.

In VATUSA airspace all aircraft are assumed to be RVSM capable thus the NEODD/SWEVEN rule extends up to and includes FL410 (eastbound). Above FL410 2,000ft separation is still required so FL430, FL470 & FL510 are westbound and FL450, FL490 & FL530 are eastbound. The "in-between" even altitudes such as FL420, FL440 etc. are not used.

One thing to note is the atmospheric pressure affects the usable flight level. For example, an aircraft files for a final altitude of FL180 and the atmospheric pressure is 29.80. Using the chart below you will see that the lowest USABLE altitude is FL190. What do you issue instead? The pilot has filed for FL180 (even flight level) therefore ask the pilot if they would prefer 16,000 feet or FL200.

Flight Levels and the Altimeter

Altimeter Setting Lowest Usable FL

  1. 29.92" or higher - FL180
  2. 29.91" to 28.92" - FL190
  3. 28.91" to 27.92" - FL200

ALL FLIGHT PLANS MUST INDICATE THE CORRECT ALTITUDE FOR DIRECTION OF FLIGHT. Any changes in the altitude must be updated in the flight strip PRIOR to takeoff.

VIII. Clearance Delivery Examples

Now, let's look at some examples of the clearances that you, as Clearance Delivery, would give. Note the phraseology used. Correct phraseology is critical between a controller and pilot. It eliminates the chances of a misunderstanding.

Clearance Using Departure Procedures


  1. AAL503: Good afternoon Seattle Clearance, AAL503 requesting IFR clearance to San Francisco.
  2. SEA_DEL: AAL503, Seattle Clearance, Cleared to San Francisco Airport HAROB6 departure, ERAVE transition, then as filed. Climb via SID except maintain 7000. Departure frequency 125.6 and squawk 1500.

Have you picked out the C.R.A.F.T. from the above clearance? Let's see...

  1. Clearance limit - "San Francisco Airport"
  2. Route - " HAROB6 departure, ERAVE transition, then as filed"
  3. Altitude - "climb via SID except maintain 7000"
  4. Frequency - "Departure frequency 125.6"
  5. Transponder - "squawk 1500"

By using this method you will always guarantee a professional clearance.

The pilot is not required to read back the entire clearance unless a change has been made. Any time you feel the pilot misunderstood the clearance it can never hurt to have them read back the clearance in full. It is always better safe than sorry.

An unchanged flight plan readback response from the pilot would look something like:

  1. AAL503: OK, we are cleared as filed. Climb via SID except maintain 7000. Departure frequency on 125.6 and we'll be squawking 1500.

EXAMPLE 2: Incorrect DP Filed

The following example flight plan is shown as SUMMA1 BKE RBG J143 ENI GOLDN4. Clearly, the pilot made an error. Issue the preferred route.

"SEA_DEL: AAL503, Seattle Clearance, this will be a full route clearance, advise ready to copy."

"AAL503: Ready to copy."

"SEA_DEL: AAL503, Cleared to San Francisco Airport, HAROB6 departure ERAVE transition, Q1, ETCHY, MLBEC, BDEGA3 arrival. Climb via SID except maintain 7000, Departure frequency on 125.6, squawk 1501."

This time the pilot MUST read back because of the changes. The entire read back would be:

"AAL503: We are cleared to San Francisco via the HAROB6 departure ERAVE transition, Q1, ETCHY, MLBEC, BDEGA3 arrival. Climb via SID except maintain 7000. Departure frequency on 125.6 and squawk 1501."

There is one thing to note about this last example. If the pilot reads back the clearance this means that the PILOT and ATC agree on this flight plan. If the pilot is unable to accept the departure then it is the responsibility of the PILOT to decline the clearance.

EXAMPLE 3: Clearance Not Using Departure Procedures

AAL503 is flying to KLAX and filed BTG LMT AVE SADDE6 with "NO SID" in remarks

"SEA_DEL: AAL503, Seattle Clearance, Cleared to Los Angeles Airport via the Seattle one six one radial, expect vectors to Battleground as filed, Maintain 7000, expect flight level 350 15 nautical miles from Seattle VOR, Departure frequency 125.6, Squawk 1505 "

Clearance of an IFR-VFR Flight

Occasionally a pilot will come along and request an IFR release and tell you that they will be going to VFR at some point in time or at a fix. Here at Seattle, the most common are the military aviators who fly out to a Military Operations Area (MOA) and then switch to VFR flight within that airspace. Your responsibility is basically the same, BUT you must ask the pilot at which point they will cancel IFR, and that becomes the clearance limit. An example:

  1. NAVY25: Good day, Seattle Clearance, NAVY25 requesting IFR clearance to Olympic MOA then we'll be going VFR after Hoquiam.
  2. SEA_DEL: NAVY25, Seattle Clearance, Cleared to Hoquiam VOR via the Seattle 161 Radial, expect vectors to Hoquiam. Maintain 7000, expect 14000 15 nautical miles from Seattle VOR, departure frequency 125.60, squawk 1503.

Clearance of a VFR Flight

VFR aircraft also need clearance to depart from KSEA. They do not get a departure procedure, but they do need clearance to operate in Class B, and they need a squawk code.

Note: Sim Pilots often don't understand the difference between a VFR clearance and an IFR clearance, so you may have to question the pilot about their intentions. If they just want to fly around the Seattle area sightseeing, then they almost always should be given a VFR clearance. If they're flying somewhere far, or in a jet, then they probably want an IFR clearance. In the real world, pilots have to get an IFR clearance if they're going to fly in clouds or reduced visibility (usually less than 3 miles), or higher than 17,999 feet. If the cloud ceiling at KSEA is 500 feet and visibility is down to 1 mile in mist and a pilot wants to go VFR sightseeing, check to see if their Flight Simulator is using real-world or VATSIM weather; if so, advise them that a VFR sightseeing flight might be difficult!

  1. N12345: Good afternoon Seattle Clearance, Cessna 12345 requesting clearance for VFR departure to the west.
  2. SEA_DEL: Cessna 12345 Seattle Clearance, Cleared out of Seattle Tacoma Class Bravo Airspace, maintain VFR at or below 2,500, departure frequency 125.6, squawk 1522.

With SEA_TWR's permission, aircraft can remain in the pattern at KSEA. The clearance is as follows, once you obtain permission from tower: Cessna 12345, Cleared to enter Seattle Tacoma Class Bravo Airspace, maintain VFR at or below 1500, squawk 1502.

Note the difference between "Cleared out of Bravo Airspace" and "Cleared to enter Bravo Airspace."


Further readings, we suggest:

  1. FAA 7110.65 Chapter 4 Section 2
  2. FAA 7110.65 Chapter 4 Section 3
  3. FAA 7110.65 Chapter 4 Section 5
  4. FAA 7110.65 Chapter 2 Section 4
  5. FAA 7110.60 Chapter 7 Section 9
  6. VATUSA Basic ATC Study Guide