BFI Controller voiced concern regarding the immediate conflict that develops when traffic on the ILS 13R begin a missed approach early in the procedure for whatever reason; the reporter listed a number of steps that could be initiated to provide resolutions to the problem.

Narrative

I was conducting on the job training on Local Control position. Weather was IFR. Aircraft X; a C421 on Runway 13R ILS approach; advised on approximately a 3 mile final at 1;800 FT that he was going missed approach due to faulty gear indication. I instructed him to maintain 2;000 FT and to fly heading 130; and issued traffic; 'eleven o'clock; one mile southbound; B737 at 2;300 FT'. Crossing traffic was inbound to SEATAC Airport. Aircraft X advised that he was VFR on top. Aircraft X said that he had the B737 in sight. I told him to maintain visual separation with the traffic and after courses diverged I told Aircraft X to contact Seattle Departure Control. Our facility does not have safe missed approach procedures/policies in writing that protect IFR missed approaches executed early; way before the decision height; which conflicts with SEATAC Airport IFR arrivals whose flight paths cross overhead our airspace and airport. In a south flow; the current Letter of Agreement (LOA) between Seattle Tower; TRACON and Boeing Field says to instruct the aircraft to maintain 2;000 FT and to fly heading 130. In recent weeks management and the Union have tried to modify the LOA to resolve this problem which has been ongoing for decades; but the modifications do not ensure safety or legality if the missed approach is executed early; such as an aircraft climbing who is responding to an RA; an aircraft with a faulty gear indication; an aircraft too high on the glide slope; etc. In the past week alone we have had 3 early-occurring missed approaches; approximately 3 to 3 1/2 miles on final; that I observed; the third event being the one described above. Many worse case scenarios can occur and have occurred; and the LOA does not legally or safely solve the problem. The airplanes are unprotected and so are we as controllers at BFI because we have just a few seconds to decide whether or not the maintain 2;000 FT; runway heading instruction is the safest course of action. Sometimes it isn't; so we are forced to use our best judgment; but then we are charged with an Operator Error because of MVA constraints; etc. After the event with Aircraft X; it was discovered that our Seattle TRACON shout line was inoperable; BFI could call TRACON but they couldn't call us back; so critical seconds were lost here. Note: the LOA procedure to coordinate using the shout line is problematic because there is typically a delay in getting a quick response from the TRACON; most of the time. Recommendation: 1. Evaluate the S46 shout line and coordination procedures. Is coordination timely enough? Can both departure and arrival sectors hear loud speaker properly? Is there confusion because the shout line is shared by both departure and arrival? What about maintenance issues? 2. Is there a safe and legal vector and altitude to the west that BFI Controllers could issue; or get a speedily approval request from TRACON; if the missed approach occurs early on? 3. New approaches; (RNP); to SEATAC Airport which might raise the flight path over our airport or change the course so when they turn to join their final that they are higher over our airport? This might be costly; but the airlines could probably come up with new approaches. Form a task group with the airlines user groups based at SEATAC and Boeing Field to work with the FAA and the Union(s) to create new approaches and procedures. GPS is already here; use the technology to make it safe.