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Posted: Wed Oct 25, 2017 12:17 am
by Peter Armstrong
Recently, I have had discussions with my fellow controllers with respect to the departure/arrival and pattern work (VFR) at KSEA.

There have been many different opinions on this subject. My opinion is as follows:-

VFR A/C departing and/or arriving at KSEA require as part of the instruction “Cleared to operate within the SEA Class Bravo Airspace”. Assuming that they are departing out of the Class Delta and arriving via the Class Bravo.

For VFR Pattern work I do not use that instruction. Why? Because the pattern work is normally flown within the 5 mile Class Delta airspace and below 3000ft.

Any comments would be welcome. :teach:


Posted: Wed Oct 25, 2017 2:49 am
by Frank Miller
The surface area of the Bravo and the KSEA Class D coincide in the immediately vicinity of KSEA. I believe a VFR a/c still needs an explicit Bravo clearance to stay in the pattern at KSEA. The more restrictive airspace takes precedence where airspace with different classes/restrictions overlap (see AIM 3-1-3(a) for example).

One point here that is worth noting is that a VFR departure from KSEA is often given a hard altitude of 2500 to depart the Bravo. I sometimes hear SEA Tower controllers instruct the a/c to “squawk VFR, resume own navigation, maintain VFR altitudes at all times, frequency change approved” when the a/c reaches the Bravo surface level threshold. If the a/c is still inside the KSEA Class D airspace (over Puget Sound, for instance) the Tower should not give them the frequency change until they are leaving the Class Delta.



Posted: Wed Oct 25, 2017 3:56 am
by Peter Armstrong
Some interesting material from our Training Documents
I. b. The clearances for the circuit are as follows:
II. i. Cessna 123AB make closed (left/right) traffic, runway xxx, report midfield downwind each pass.  Wind-runway-cleared for takeoff.  The aircraft is NOT departing;  so a departure instruction is not necessary. A departure instruction includes the phrase "cleared to operate within the SEA Class Bravo Airspace" (at or below 2500)

Seattle Class D (Delta) airspace extends out to 5 miles from the center of the airport and up to 3,000 feet MSL. VFR pilots are required to establish two-way radio communications before entering the Class D airspace. If you respond to their radio call with, "N182D standby," radio communications have been established and the pilot can enter the Class D airspace. (Assuming he is under 3000ft)

(100 Class Bravo Ceiling) (30 Class Bravo Floor)
It is possible for aircraft to operate while under the floor of Class Bravo and not receive ATC approval. If the aircraft will be operating below Class Bravo floor AND inside your 5 mile airspace then it is a good idea to advise SEA_APP or SEA_DEP that you have control of that aircraft