Basic Separation

Class D

IFR>IFR: 3 miles laterally, 1,000 vertically, or visual separation

IFR>VFR: Traffic Advisories and Safety Alerts

Class C

IFR>IFR: 3 miles laterally, 1,000' vertically, or visual separation

IFR>VFR: Visual laterally, 500' vertically, or Target Resolution

VFR>VFR: Traffic Advisories and Safety Alerts

• Target Resolution: The targets on the radar can not touch.

Note that per 3-9-5 you do not have to wait until separation exists to issue a takeoff clearance. You are allowed to issue the clearance when you anticipate that the separation will exist when the aircraft actually starts its takeoff roll.

Visual Separation

As long as another form of separation initially exists between aircraft, visual separation may be applied to allow the aircraft to get closer than regular minima. (7110.65 7-2-1) There are two types of visual separation:

• Tower-applied: The tower visually observes the aircraft (using CRC cab view), issues timely traffic advisories, and provides visual separation between the aircraft. Maintain communication with at least one of the aircraft involved. Do not apply visual separation between successive departures that may conflict or when wake turbulence separation is required (see below).

• Pilot-applied: Tell the pilot about the other aircraft. Obtain acknowledgment from the pilot that the other aircraft is in sight. Instruct the pilot to maintain visual separation from that aircraft. Maintain communication with at least one of the aircraft involved and ensure there is an ability to communicate with the other aircraft.

Same Runway Separation

There are 3 types of same runway separation: General, Category, and Wake Turbulence, with special wake turbulence requirements for intersection departures.

General Separation - Separate a departing aircraft from a preceding departing or arriving aircraft using the same runway by ensuring that it does not begin takeoff roll until (1) the other aircraft has departed and crossed the runway end or turned to avert any conflict or (2) A preceding landing aircraft is clear of the runway. 

Category Separation - Category separation is simply separating aircraft by category alone. There are 3 categories of aircraft: Category I, Category II, and Category III

• Category I - Small single−engine propeller-driven aircraft weighing 12,500 lbs. or less, and all helicopters. Example: C172, P28A

• Category II - Small twin−engine propeller-driven aircraft weighing 12,500 lbs. or less. Example: PA44, C402

• Category III - All other aircraft.

Note - Categories set forth in 3-9-6 of the 7110.65 are for SRS only and should not be confused with categories as outlined in SOPs or LOAs. The categories mentioned in these SOPs are used when determining items such as initial altitudes and departure headings, therefore should not be used interchangeably with SRS categories.

Category separation is applied by separating aircraft by a specified number of feet. This is the lateral distance, not vertical. This distance must exist by the time the second aircraft starts its takeoff roll or crosses the landing threshold. Separation is as follows:

• Category I Behind Category I = 3,000 feet

• Category I Behind Category II = 3,000 feet

• Category II Behind Category I or II = 4,500 feet

• Either is a Category III = 6,000 feet

You do not have to memorize this list.

CWT Categories will show up on ASDE-X, STARS, and Flight strips

Wake turbulence separation may be applied in two different ways: In minutes or in miles.

If you are in a tower with a STARS display or radar towers, we may use miles, which is much quicker than minutes, but it is still important to know both. There are, however, certain instances where you can only use time for wake turbulence separation (mentioned and required for intersection departures).

When utilizing minutes for separation, the time starts when the first aircraft lifts off the runway. When utilizing miles, the appropriate radar separation must exist by the time the second aircraft is airborne, meaning the distance need not exist when issuing a takeoff clearance.

Any of these time intervals may be waived if:

• The intersection is 500 feet or less from the departure point of the first aircraft.

• Successive touch-and-go or stop-and-go operations are being conducted, and the aircraft is maintaining visual separation/spacing from the departing aircraft. A wake turbulence cautionary advisory must be issued.

Note - Aircraft conducting touch-and-go and stop-and-go operations are considered to be departing from an intersection.

CWT Card reference found HERE. Save for when you need it