B707
Flight Crew Flight Instructor; Flight Crew Private
Flight Crew Last 90 Days 110; Flight Crew Type 3500
Situational Awareness
Conflict Airborne Conflict; Deviation - Altitude Excursion From Assigned Altitude
Air Traffic Control Issued Advisory / Alert; Flight Crew Took Evasive Action
Airport; Human Factors; Airspace Structure
While getting vectors for the RNAV approach into runway 13 at Forbes Field (FOE); ATC controller notified the crew of 'traffic 12 o'clock; 5 miles; descending.' The crew acknowledged and reported; 'Searching.' The ATC controller then notified the crew of 'traffic 12 o'clock; 4 miles; descending; traffic is VFR and not in contact with us.' The crew acknowledged and reported; 'Negative contact but we have him on TCAS.' The controller then stated; 'Traffic still 12 o'clock; 3 miles now and continuing to descend through your altitude. Would you like to turn or continue the approach?' The crew immediately received a TA (TCAS-generated Traffic Advisory on the intruding traffic and then asked for a left-hand turn away from the traffic. The navigator then visually spotted the traffic. As ATC gave us a left 360 degree turn; the crew received a subsequent RA (TCAS-generated Resolution Advisory) to 'Climb; climb.' The crew believes this is when the pilot of the other aircraft first saw us and increased his climb to avoid. The TCAS aboard our aircraft amended the RA based upon this new geometry just prior to announcing; 'Clear of conflict.' Other contributory factors could be the fact that there was another 707-type aircraft (a KC-135 Tanker with a different callsign) on short final on the opposite side of the C-182. The difference between a KC-135 and a RC-135 are minor to a novice and from a distance greater than 1 mile. That other KC-135 traffic was about 5 additional miles away and already with Forbes Tower. The crew believed the pilot of the C-182 became fixated on that aircraft and not on us. Fixation terminated when we began a climbing turn; causing a shift away from the 'constant bearing; decreasing range' perception in the other pilot's peripheral view. This factor was exacerbated by the fact that the RNAV into FOE runway 13 takes you through the flight path into TOP and vice versa. These factors were somewhat confirmed in a phone conversation with the other pilot after the sortie. The other aircraft was a C-182 VFR into TOP.
RC135 pilot on vectors to the RNAV 13 at FOE; experiences an airborne conflict with a C182 VFR to TOP. A TCAS RA to climb is generated aboard the RC135 then reverses just before announcing clear of conflict.