comments on DC-8 Transpacific flight

[Mace_RB 41]

This isn't a tech support post.  This is just a story-type post for those interested in INS flight.  I just completed a trans-pacific flight (RJAA to KLAX) in the DC-8.   I of course used the INS for navigation, as I was far away from any VOR's. 

 

So I had more than 9 waypoints, a topic which has come up on this forum before.  I did not enter 9 into one box, and 9 in the other...that's not good practice.  So, what I did was, enter the first nine (9) waypoints in the INS (both INS's, using the REMOTE key).  Those nine waypoints got me to 170 degrees West latitude.  A little over halfway.  Shortly before reaching waypoint  #9  (46degN, 170deg W), I ensured that my heading bug was set to my present course, and then switched over to HDG mode on the autopilot.   This allowed the aircraft to continue flying straight, and yet freed me to enter new waypoint data.  Not sure if that is proper technique, but that's what I did.

 

By this time, yes, my INS precision was low (at 9 already) -- but I had no set radio or dme fix to re-calibrate it.  Therefore, I had to trust and rely on the INS as is.  So, I began entering new waypoint data...starting with point 1, and progressing on to finish out my flight plan (it finished on 9, nicely enough).  I reset the INS to begin leg 1 to 2, then switched the autopilot back to INS, and the aircraft began following its new course.

 

Long story short, I came ashore very close to my desired spot -- Monterey Bay, California -- and quickly re-calibrated my INS by overflying the Salinas VOR.  After not seeing land for 10+ hours, it was a pretty amazing feeling to see the lights of San Francisco (it was night time), and know that I did it -- the INS did it -- and I wasn't 200 miles out to sea, or something like that.    Good flight, that's the kind we like, using the old-school nav techniques.