NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Pressure line of position
From: Ronald P Barrett
Date: 2010 Dec 24, 05:31 -0800
From: Ronald P Barrett
Date: 2010 Dec 24, 05:31 -0800
| Gary and all, I flew over 3,000 hours in unpressurized C-124s mostly over the South Pacific in the 60s at altitudes usually around 9,000 feet MSL. We Navs used pressure pattern PLOPs all the time. They were very useful. PLOPs required we do the normal DR-Ahead chart work, have a MB-2 (whiz wheel), a calibrated TAS indicator, decent heading compass:usually a D-1 system, a pressure altimeter set at 29.92, or just left on its setting for the entire duration as the autopilot flew this(stayed on a constant pressure surface), and most importantly:the SCR-718 radio-altimeter. Reading the SCR-718 circular rings with pips on the 4 inch diameter-lil'screen of the SCR-718's face(a CRT tube presentation that looked like an oscilloscope) was an art! The SCR is what allowed you to determine actual surface to aircraft altitude (AGL). Without it one could not read AGL. Most all of the USAF cargo planes had this capability, and up to the B-52, so did the Bomber fleet. If the Nav paid real attention to the weather, did PLOPs, he then could report all this via an key (yes there were keys in the old planes) or voice HF radioed "PIREP" back to the area Command Post. Usually done hourly. The flights were normally 10 to 14 hours long. This assisted the area weather folks in knowing what was happening in the days prior to weather satellites. Good Celestial, Loran, Doppler, Inertial and now GPS made PLOPs fade away. Ron Barrett, Air Force Navigators Observers Association, Historian --- On Fri, 12/24/10, Gary LaPook <glapook@pacbell.net> wrote:
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