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Posts posted by Iridium

  1. On 4/9/2019 at 5:26 PM, Stephen said:

    The VNAV button is the one for auto following the altitude, but I rarely use it as a lot of FMS's are inconsistent. You can do your own V/S far more accurately and more like the professionals. Rule here is to set the Altitude to 15,000ft at 2000fpm (then increase speed to just over 300knts), then to altitude (say FL300/30,000ft), but change the V/S down gradually at say 23,000ft to 1500fpm, then at 26,000ft then 1000fpm... try it.

    In climbs, an airspeed hold should always be used rather than a vertical speed hold. The reason is that as you climb higher, the aircraft will need to pitch up more in order to maintain the desired vertical speed, which means you will bleed off airspeed and eventually stall. Above ≈FL290, you should be holding a constant mach rather than a constant IAS. The climb profile I use when I fly this plane in real life is as follows: (usually) 200KIAS to 2,500ft (above field elevation, or AFE). Then, provided there are no other departure speed restrictions, speed up to 250KIAS until 10,000ft MSL. Then transition to 270KIAS until IAS/Mach transition (usually ≈FL290), at which point I maintain 0.73M until cruise. At cruise, the airline I fly for wants us to maintain 0.75M, but the aircraft is usually capable of faster speeds (depending on weight and atmospheric conditions). In the descent, I like to maintain 0.75M until the Mach/IAS transition altitude, at which point we typically transition to 290KIAS (unless otherwise required by the descent or ATC). Flying into KPDX on the TMBRS.2 or KRATR.2 arrivals, we maintain 280KIAS until 10,000ft MSL, at which point we slow to 250KIAS until further slowed by the STAR (or ATC).

    Getting back to my original point, V/S for descent can be okay, but a speed hold (such as FLCH) is the only climb method that should ever be used. Momentary usage of V/S for short climb durations (to quickly expedite a climb) can be used, but you need to pay very close attention to your airspeed. 

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