See list attachedFebruary 6, 196969-PA-T-17APA/Chief, Apollo Data Priority CoordinationMCC-H Ascent Monitoring
This is a note primarily to myself to remind me of impressions obtained during the MCC-H Ascent Monitoring meeting of January 24, 1969. Although it appeared that the prime program for processing MSFN data was to be the “Lear,” I feel quite strongly that the old, direct doppler-measurement technique should be retained for in-place monitoring. The only situation it cannot support is ascent from the central landing site with a bad z-axis accelerometer. It seems to me, at least for now, that the Lear-Processor should only be used prime for out-of-plane – the situation the old technique can do nothing for. According to Steve Bales, their plans for RTCC program and MCC-H display implementation are in complete accord with this idea. It is only necessary to make the decision to do it this way on the G mission.
Another thing I am particularly concerned about is an apparent willingness to allow the trajectory to become badly dispersed before switchover from a failing PGNCS and thus to accept what could be a very poor rendezvous situation compounded by a failed PGNCS to do the rendezvous. In order to avoid this, two things must be done.
a. First, we must determine how serious it is to switchover to the AGS as soon as it is recognized that the PGNCS is not working as well as the AGS. This you see is not a question of pre-flight expected per- formance of the two systems but rather actual, observed performance in real time. The only reservation against switchover, it seems to me, is the hazard incurred by the actual operation of switchover itself.
b. Secondly, there appears to be a need to establish display action lines or techniques involving displays other than the predicted insertion display. This is necessary since the predicted perigee vs. wedge angle display do not reveal a problem until long after it occurs. It seems to me it should be possible to establish some technique which would result in taking action much sooner. One consideration which must be analyzed before adopting this technique, however, is to determine the effect of delaying the switchover action since, if the AGS is capable of returning the space- craft to a near nominal trajectory at little ΔV cost, there is no point in taking the action early.