Since Carleton demonstrated so much knowledge of flight control, I asked him if he had a pilot's license. He told me that he also earned a flight instructor's license before his employment with Amtrak.
---- Original message ---- >Date: Fri, 23 Apr 2010 22:45:00 -0400 >From: "Carleton MacDonald" <[email protected]> >Subject: [USMA:47254] Re: Air flight altitudes in meters >To: "U.S. Metric Association" <[email protected]> > > >Radar altimeters are generally not used to clear mountains. (You'd be too >close by the time it went off.) Enroute terrain clearance is achieved under >instrument (controlled) flight rules by altitude assignment; under visual >flight rules by minimum altitude indications on each sector of the sectional >map. > >Radar altimeters ARE useful on landing approach because they provide a >direct indication of height above ground. A regular pressure altimeter >shows your height above sea level (roughly), and you have to subtract field >elevation (the airport where you're landing) from that in order to know >(again, roughly) how high above the ground you are. > >Altimeter settings in the USA are used below Flight Level 180. (FL 180 is >determined by setting your altimeter to standard pressure (101.32 kPa or >29.92 in Hg) regardless of what the actual barometric reading is; since all >airplanes are setting to standard pressure at and above FL 180, they all >have the same altitude reading relative to each other. (The altitude >reading is only reasonably accurate if the actual air pressure where they >are happens to be the standard pressure.) Below FL 180, the controller >gives the pilot the actual pressure of a nearby airport (or the pilot >listens to an recorded radio reading of it). It's also part of the hourly >weather report for an airport. In the USA unfortunately it's still given in >inches of mercury. >...
