Leaderboard

Collin's Nav-to-Nav transfer has always been finnicky, whether it was the PL4, PL21, or PL21 Enhanced. There are many things that can trip it up. One is executing an FMS change on legs page right at the 30 NM distance from ARP. If that happens, the LOC may tune but the CDI will auto set to the inbound course. Found this out the hard on the LDA Rwy 25 into KEGE one day after ATC cleared direct to QNDRY just as we were passing the 30 NM from ARP point. The LOC tuned on both sides, and it auto set the inbound course on the right side (I was PM that leg) but on captain's side, it didn't set the inbound course correctly. When APPR was pressed passing AIGLE, which you must do on this approach because of the stepdown fixes in the intermediate segment are above the LDA GS, we found the CDI turned about 90 degrees from the inbound LDA course. Hold the DME at the wrong time, like on the ILS 6 at TEB is another trap for Nav-to-Nav transfer. Hold the DME after it has done the Nav-to-Nav transfer tuning inside the 30 NM from the ARP. Rich Boll

A couple of quick comments... On an ILS approach, when "cleared for the approach", do not select APPR mindlessly. You need to look at what's ahead on the approach leading into the FAF. There's a very simple reason. If you capture the glideslope, following the glideslope will not guarantee compliance with intermediate segment stepdown fixes. A good example of this is the LD Rwy 25 approach into Eagle, CO (KEGE): 06403LDA25 (faa.gov) This approach has a glideslope. You're normally cleared for the approach around RLG or QNDRY. As you turn final, you may be above GS, maybe not especially on hot day. If you capture the glideslope, on hot day, you will descend below the stepdown fix altitudes at WEHAL and AIGLE. On a long ILS approach like you find at ORD, IAD, IAH, DFW, etc, with multiple intermediate segment stepdown fixes, on a hot day, the glideslope will take you below those altitudes. Those altitudes are required for the 1000 ft. separation at turn during parallel runway operations. Back in 2010, after the new runways at ORD opened, there were bunch of CRJ pilots flying Collins aircraft that got pilot deviations for following the training school mantra of "cleared for the approach - arm APPR". That works the sterile environment of the flight simulator. It does not work in real life. Even the Collins SBAS system can get you into trouble. There's a little known issue with the Collins SBAS FMS when an RNAV or RNP APCH approach is loaded. If the aircraft uses the Jeppesen database (the Lufthansa database option is not affected), passing the intermediate fix which is labeled (IF), the FMS will begin using SBAS vertical guidance in place of Baro-VNAV guidance. And it does not matter if VNAV or VGP is displaying. SBAS vertical guidance is not affected by temperature, just like the ILS glideslope. If the temperature is hot, like it is now in DFW, following the VNAV path on a RNAV/RNP approach like the ones on runways 17L/R will take you below the stepdown altitudes. Nothing can be done about it, except using VS mode. I've been curious as to whether this is simulated in HS 650??? If you would read more about, refer here: Hist 19-02-344 (faa.gov) Second, as for the obstacle protection below the DA on an ILS or RNAV or RNP APCH approach to LPV minima, the obstacle protection is exactly the same. The same is true for RNAV RNP APCH approach to LNAV/VNAV line of minima or an RNP AR APCH to any RNP line of minima. The TERPS PANS-OPS obstacle protection surfaces are the same once you're below DA. Now if you are flying an RNAV/RNP approach to LNAV only minima, then the answer is YES. There is NO obstacle protection once you descend below MDA. If you want to find out more about this subject, read this: Hist 12-01-301 (faa.gov) Best regards, Rich Boll