Md11 Fault In Trk Indications

[Guest mcpfma]

Stablished on ILS RWY 01 with autoland engaged, Crosswind 060

[downscc 1,327]

To GREETINGS and THANKS: Please sign your name here, it is one of the rules.Regarding the TRK monitoring on approach: A couple of weeks ago someone else was trying to use TRK for an approach and I refrained from jumping in. Track is a derived value, basically it is the direction on the ground between where the aircraft was and where it is. Heading is an instantaneous value, the aircraft has one value for heading at any given instant. I would not use TRK mode on an approach for guidance, and find that the computed values for track are nonething more than interesting. The key variable is the aircraft position with reference to the desired course, which is indicated directly (not derived) by the course deviation indicator (CDI) or localizer needle as it is commonly referred to. On a typcial crosswind approach, the CDI is maintained on center by varying heading or in the case of an FMS the CDI is driven either by the dual LOC receivers or a computed COURSE derived from GPS and IRS data. Tricky subject. Anyway, it is called an approach course (not track). I honestly don't think the computer programs in the real bird are designed to provide an instaneous value of TRK that can be used for an approach, and I am not surprised that it is not modelled in the MD11.I watched the MD11 from the spot position on a cross wind landing the other night and I was amazed at how realistic it looked (I have been landing in Corpus Christi crosswinds for 8 years and attest to having some knowledge of this art form).

[Guest rellehenk]

downscc,In real life, we make non-precision approaches/visual approaches with TRK/FPA and it works very well!TRACK and HEADING are computed by the Inertial Reference Units and are therefor very accurate.Floris