richjb

Beginning with ver 1.5.2, I have been getting frequent V-SPEEDS DELETED CDU messages, and finding that the VREF, VAC, and VFTO speeds have reverted to white instead of pink. They are also not showing the PFD airspeed tape. Today, while flying a circuit around KICT's ILS 19L, I had to reset the V-speeds about 6 times including twice on final approach. I noticed this on previous flights after upgrading to 1.5.2. No idea why. I didn't change any performance parameters. I did extend the final approach course on the ILS 19L, but that should have affected it. This was not an issue with ver. 1.4.x but did begin with ver. 1.5.2. Thanks for you assistance! Rich Boll

I've been experimenting with engine failure on takeoffs, just above V1, the so called V1 cut. So far, I have not been very successful. While I have been able to counter the initial yaw with the nosewheel on the runway, after rotation begins, there is insufficient rudder authority/effectiveness(?) to correct the yaw both in and out of ground effect. I have the flight control page up and the Developer>Show Flight Controls window open. From both indications, I am getting full rudder deflection. Yet out of ground effect, with the wings level, the slip indicator (i.e., doghouse) is about 3/4 displaced towards the operating engine, indicating more rudder is required. The good thing about HS CL650 is that you have the yaw/roll coupling inherent with sweptwing aircraft modeled very accurately. The bad thing is that because of the excellent modeling, the lack of sufficient rudder authority/effectiveness means that the aircraft at V2 is rolling off into the dead engine, making it very difficult to fly. I have much experience in how V1 cuts work, teaching them in the LJ-JET series Level C simulator for many years, as well as being type rated in the Lear 45/75, DA2000, and CL300/350. I suspect that the CL650 with its hydraulic rudder would be very close to the CL350, and at very light weights where V1 is near V1/VMCG, full rudder will be required. I have been practicing these at 35,500 lbs. V1 is 114, VR is 121, and V2 is 131. I'm taking off from KICT's runway 1R on pretty much a standard day. Yesterday, I did some heavyweight takeoffs at 45,000 lbs. hoping the rudder control, authority, effectiveness would be a little better. It was not. Although, the performance following the engine failure was pretty close to what I would expect without digging into the AFM. I am fairly new to XPlane beyond more than casual users. The quality of addons in XPlane has now made it my sim of choice. Is there any way that I can tweak the rudder on this model to see what might work better, and report back to you folks? Any suggestions would be greatly appreciated. Thanks! Rich Boll

Thanks! Rich

Thanks oisin650! I have not had the chance to get the CL650 up to altitude. I spent yesterday doing CPT/SIT training in it since I had to re-set my presets. Quick question, is there any way to get the nose gear doors open without power and 3A hydraulic pressure in order to get the nose gear pin out? Thanks! Rich

I am hearing rumors that some operators are applying the 60% or 80% factor to the OLD Data for dispatch. Ouch! That's not how that works. Still peeling the onion back on this one. Rich

Thanks sir! I was not aware that EASA pulled the trigger on the 80% option. Good to know. I do know from my FAA performance engineering contact, who retired at the beginning of the year, that FAA and EASA are working to harmonize these rules and regulations, both for airplane certification and operations, including on wet and contaminated runways. More changes in the offing, but I'll be retired by them! :-) Thanks for the CL650 OLD data! Rich

Depend on the operator and what they have available. Many operators use a flight planning service that also contracts with a performance engineering service provider. For the business aviation fleet, that is usually Aircraft Performance Group: Aircraft Performance Group: APG (flyapg.com) APG provides the airline-style airport runway analysis. If you're familiar with TOPCAT (FlightSimSoft.com), it is the same thing. You would simply run a landing analysis report for the airport of intended use and then see if the maximum landing weight meets your requirements. In the US, for part 135 or 91K operators, their minimum field length is normally based on actual landing distance allowing the aircraft to stop within 60% of the runway's declared landing distance available. This minimum field length is increased by 15% if the runway is forecast to be slippery or wet at the ETA. Some operators can reduce the runway required to where the actual landing distance will bring the aircraft to a stop within 80% of runway's LDA. With EASA, they do not permit this type of reduction...yet. Last I heard, they are looking at it. On the QRH for the CL650, for different pressure altitudes there is a chart that provide the "LFL" or Landing Field Length both for a dry runway and a wet runway for each weight at a given pressure altitude. Since LFL "assumes" standard temperature, there are no corrections provided for temperature. The chart for a given pressure altitude also give the actual landing distance (ALD) at various landing weights and temperatures. These QRH chars can be used if you do not have access to an airport runway analysis service. One more thing to consider is the landing climb requirement and approach climb requirement. Landing climb requires a minimum 3.4% climb gradient, 8 seconds after go around thrust is selected, with the aircraft in the full landing configuration. Most turbojets, this requirement is not limiting. The other requirement is the approach climb requirement, which requires a 2.1% climb gradient at maximum go around thrust with one engine inoperative, in the approach configuration for a go-around, and with the landing gear retracted. This a "spot" or snapshot performance requirement at the start of the OEI go around. On the QRH charts, I noticed that ALD data is not provided above certain temperatures at certain higher pressure altitudes. Most likely reason is that the aircraft does not meet the approach climb requirement at those pressure altitudes and temperatures. A closer look at the performance charts in the AFM would likely confirm. If you would like a good primer on transport airplane performance, may I refer you to the NBAA website that host the FAA TAPP WG performance videos: Aircraft Climb Performance Videos | NBAA - National Business Aviation Association They're also available on YouTube from the FAA. Here's the first of four: Thanks, Rich Boll

Thank you for pointing out the LDTA and RCAM. I don't have one for the CL650 but do have one for the CL605 See below. This is the Operational Landing Distance data for use with the reported Runway Condition Codes (RwyCC). At the end of the document, there are factors for each RwyCC that can be entered into the FMS APPRAOCH REF 2/4 page in the LAND FACT field. Make sure that you're default is to actual landing distance (ALD) and not factored landing distance when applying the OLD factor. Rich Boll Operational Landing Distance (OLD) CL605.pdf

Worse yet, they mix them. Some states are using PANS-OPS for procedure development, but then not applying the requirements for those procedures during flight operations. For example, PANS-OPS in some circumstances requires the use of an alignment hold to enter a procedure turn or teardrop course reversal. There is one state in the western hemisphere that designs their approaches based on PANS-OPS with the alignment hold published, but when you say you're going to do it, it can throw ATC for loop because they are not expecting it.

In the US, the FAA does not apply any visibility penalties if the pilot/flight crew uses "dive and drive" verses CDFA. It is the EASA-driven, State operating rules that require European operators to increase their visibility minima for an approach if they elect to not use CDFA and "dive and drive" instead. There is some school of thought with the US and FAA that "dive and drive" is still appropriate for NPA. I agree with that when circling is required. However, for most NPA straight-in approaches with straight-in landing minima, CDFA is more appropriate. Rich

In fairness, I've seen error with interpretation and application with both providers. I work with both Jeppesen and Lido representatives in my day job. Don't get me wrong, they both do a good job of presenting aeronautical data. Lido has done some really good work with their charts. The ground movement charts are some the best. They are still reliant on State AIP information, which can be difficult to interpret and sometime can be in error. When flying internationally, it is something that bears watching! Rich

Hi XPJavelin, There is an RVR equivalent to the 1/8 and 1/4 mile as well. Many airports in the US do not have RVR, so we're more dependent on prevailing visibility as opposed to runway visibility. We still do things in imperial units, through. Feet instead of meters. It is one of the things we have get used to crossing the pond or flying down into the Caribbean where some islands follow the EASA PANS-OPS rules! Rich

Hi Javelin, Excellent research. The August 2019 Jeppesen Briefing Bulletin is attached below for the benefit of others. Pardon the extensive highlighting. Bad habit of mine. Here's my take on it. Referring to the following document: Annex to ED Decision 2012/018/R: AMC4 CAT.OP.MPA.110 Aerodrome operating minima CRITERIA FOR ESTABLISHING RVR/CMV (a) Aeroplanes The following criteria for establishing RVR/CMV should apply: (1) In order to qualify for the lowest allowable values of RVR/CMV specified in Table 6.A the instrument approach should meet at least the following facility specifications and associated conditions: (i) Instrument approaches with designated vertical profile up to and including 4.5° for category A and B aeroplanes, or 3.77° for category C and D aeroplanes where the facilities are: (A) ILS / microwave landing system (MLS) / GBAS landing system (GLS) / precision approach radar (PAR); or (B) APV; and where the final approach track is offset by not more than 15° for category A and B aeroplanes or by not more than 5° for category C and D aeroplanes. (ii) Instrument approach operations flown using the CDFA technique with a nominal vertical profile, up to and including 4.5° for category A and B aeroplanes, or 3.77° for category C and D aeroplanes, where the facilities are NDB, NDB/DME, VOR, VOR/DME, LOC, LOC/DME, VDF, SRA or GNSS/LNAV, with a final approach segment of at least 3 NM, which also fulfil the following criteria: (A) the final approach track is offset by not more than 15° for category A and B aeroplanes or by not more than 5° for category C and D aeroplanes; (B) the final approach fix (FAF) or another appropriate fix where descent is initiated is available, or distance to threshold (THR) is available by flight management system / GNSS (FMS/GNSS) or DME; and (C) if the missed approach point (MAPt) is determined by timing, the distance from FAF or another appropriate fix to THR is ≤ 8 NM. (iii) Instrument approaches where the facilities are NDB, NDB/DME, VOR, VOR/DME, LOC, LOC/DME, VDF, SRA or GNSS/LNAV, not fulfilling the criteria in (a)(1)(ii), or with an MDH ≥ 1 200 ft To use Table 6A, for a NPA approach CDFA techniques must be used. Table 6A is attached below. From Table 6A at the bottom: For NDB, NDB/DME, VOR, VOR/DME, LOC, LOC/DME, VDF, SRA, GNSS/LNAV: - not fulfilling the criteria in in AMC4 CAT.OP.MPA.110, (a)(1)(ii), or - with a DH or MDH ≥1 200 ft Min 1 000 1 000 1 200 1 200 Max According to Table 5 if flown using the CDFA technique, otherwise an add-on of 200 m for Category A and B aeroplanes and 400 m for Category C and D aeroplanes applies to the values in Table 5 but not to result in a value exceeding 5 000 m. Since paragraph (a)(1)(ii) states "Instrument approach operations flown using the CDFA technique", if you do not use CDFA technique even on these approaches where the vertical path falls within the maximum values specified, there is a 200 m (CAT A & B ) or 400 m (CAT C & D) applied. I can see where it might be interpreted the other way as well. That's what makes this so dang confusing. When I see CDFA on the approach, I interpret that to mean that I need to use CDFA on that approach. As US based operator, we do not use the State charts or the AIP. We rely on Jeppesen to figure this out for us, which is the value added service of using a provider like Jeppesen or LIDO. They provide standardized format regardless of where you fly in the world. To be honest, the who concept of AOM has been confusing as hell to US operators. We don't have to worry about this in the US because US TERPS defines the visibility minimums for every approach based on runway/approach lighting, obstructions in the visual segment, the published MDA or DA, etc. They apply to all operators. That said, back in 2010 or so, there was a change in US TERPS to allow the promulgation of visibility minima in 1/8 SM increments specifically to support the ICAO SARPS and EASA rules supporting CDFA. A European operator flying a US non-precision approach to a MDA and not using CDRA would have to increase the published landing minima for the approach by 1/8 SM for CAT A and CAT B aircraft, and by 1/4 SM for CAT C and CAT D aircraft. That's why we see approaches in the US with strange visibility minima like 7/8 SM or 1 3/8 SM. We never used to do that. Because US operators had to apply CDFA in Europe and other ICAO States that adopted the Annex 6 SARP, the FAA published AC 120-108 providing operator guidance on the application of CDFA. CDFA can be used voluntarily in the US. It's not required. You've piqued my curiosity. I may need to do further research. It's been a while since I have looked at the EASA operating rules. Thanks, Rich Briefing-Bulletin-JEP-15-A-Announcement-AOM-Concept-23-AUG-19 (002).pdf AC 120-108 Continuous Descent Final Approach.pdf 1065467017_AnnextoEDDecision2012-018-R.pdf

Thank you, sir! Rich Boll

Sure! Quick turn with no power down. Yesterday, after leaving KELD I had two quick turns in KICT and KDEN before returning to KICT. On each leg we never powered down, which normally re-sets the fuel used. When you do not power down, the only way to reset the fuel used for each leg is to press the DEL key and put DELETE into the scratch pad. You then move the DELETE from scratch pad into the FUEL USED field with the LSK and that clears the fuel used and restarts the counter in the FMS. That way, we can record how much fuel is used for current flight leg. Most operators track the fuel used on each leg. They can track metrics like fuel used per flight mile, fuel used per hour which then goes into the DOC for the airplane for cost analysis and billing purposes. Even part 91 corporate operators will usually bill back internally the per hour cost of the airplane to the unit using the airplane. What I call "funny money" because it comes out of one group's budget and goes into another group's budget. if you are flying charters, then it's very important to know the fuel burn per hour because that goes into the hourly charge for chartering the airplane. In a more practical "flying the airplane" sense, it is also important to know how much fuel has been burned from the start of the flight for the current flight leg. Let's say you left on your oceanic flight with 15000 lbs. of fuel. You're 2 hours into the flight and burned about 5000 lbs. You should have 10,000 lbs. in the tanks. if fuel gauges are showing 8000 lbs., you might have a problem. For example, a fuel leak. You might be going down the line of Air Transat flight 236, the A330 that dead sticked into the Azores after a fuel leak developed. Since that incident, most of the checklist for fuel imbalance have the pilots check for the possibility of a fuel leak by comparing fuel at block out minus the fuel used against the total fuel remaining in the tanks. If they grossly disagree then you might want to 1) think twice about balancing fuel, i.e., feeding a fuel leak from the tank(s) not leaking, and 2) consider getting on the ground before things get real bad...and real quiet. Unfortunately, Collins doesn't mention using the DELETE to reset the FUEL USED in the FMS in the CL650 FMS manual that I have, and for what it's worth, it doesn't mention it in the current CL300/CL350 manual that I have. In fact, the pages discussing the FLIGHT LOG CDU page in these two manuals are identical. I hope this helps! Rich Boll

Jeppesen began publishing the "DA/MDA (H)" several years ago when ICAO and EASA adopted the "Aerodrome Operating Minima" concept, which you see by the "Standard" annotation in the upper left corner (cut off here in this graphic") is applied to this procedure. It is one of the approaches where the pilot, if they do not have use CDFA techniques, they must add visibility penalty to the approach's minima, which also affects the approach ban. The attached Jeppesen Briefing Bulletin from 2015 was written by Ted Thompson, Jeppesen's former Direct of Standards and Corporate Technical Lead. I worked with Ted a number of years in various FAA and industry groups. Ted was able to explain how Jeppesen came to charting the DA/MDA minima on their charts. Rich Briefing_Bulletin_JEP_15A_Aerodrome_Operating_Minimums_Web_Version.pdf

I'm going to put in my two cents worth, and my procedure will differ somewhat from what the "schoolhouse" teaches. Let's talk about the easiest scenario, which is an RNAV (GPS) or RNP approach to LPV or LNAV/VNAV line of minima. The minima for these approaches are specified as a decision altitude or DA. They provide the same TERPS or PANS-OPS protection for a momentary descent below the DA as does an ILS approach. From the initial approach fix (IAF) inbound, you should have VNAV selected. You may use VVS, VFLC, or VPTH to descend the aircraft through the initial and intermediate segment step down fix altitudes, and VNAV will honor all of them. However, the easiest is to fly VPTH and let the VNAV track the vertical path through each of the stepdown fix altitudes to the final approach fix crossing altitude. You may select the APP button at any time after the final approach fix. Once selected, the Vertical Glidepath (VGP) mode will be armed (shown as a white VGP in the FMA) and will become the active mode during the in the intermediate segment sometime past the (IF) fix. There are two important things about the VGP mode: 1. It will not honor the altitude preselector set altitude. If you're not cleared for the approach, if VGP has captured, it will descend on the final past the FAF. Once VGP is annunciated in Green, you can set the missed approach altitude just like on an ILS 2. On very hot days, e.g., 40C plus, VGP may not honor intermediate segment stepdown altitudes. The reason for this is that VGP mode from the IF fix inbound uses SBAS to compute the vertical path, which is not affected by non-standard temperatures, and like an ILS glideslope will take you below the intermediate segment stepdown altitudes on a very hot day. So, on a very hot day, you might want to stay in VPTH mode until passing the last stepdown fix in the intermediate segment, then press the APP mode. You might have to use VS to vertical speed down to capture the VGP path from above. I do not know if X-Plane or Hotstart models this behavior, but this is something to watch out for in the real Collins SBAS equipped airplanes. Past the FAF, you would descend to DA in VGP mode and at DA, if the runway is not in sight, press the go-around mode and then climb out and execute the missed approach. On an approach with the LNAV/VNAV line of minima, the procedure is the same; however, VGP vertical guidance is based on Baro-VNAV. You must honor the low and high temperature limits published on the approach, but you don't have to worry about the VGP path going below the published intermediate segment stepdown altitudes. An RNAV (RNP) AR or RNP AR approach is pretty much the same thing. However, I am not sure if the Collins system uses SBAS guidance for the vertical in the final approach or if it is using just LNAV/VNAV. RNP AR approaches are a strange breed because use a "Vertical Error Budget" or VEB for vertical obstacle clearance, which was originally based on Baro-VNAV use. I actually believe it does use SBAS guidance inside the FAF/FAP, but I need to check on that. The next scenario is if you are flying an RNAV (GPS), RNP approach, or a conventional approach (VOR or NDB) using the FMS. The minimums are all based on a minimum descent altitude or MDA, which is a hard altitude that you cannot go below during the approach without the runway environment in sight. For an RNAV (GPS) or RNP approach (not RNP AR...easy to get confused since ICAO has muddled the terminology), you would fly the approach to the final approach fix (FAF) described as above except that you would remain in NAV (LNV) and VNAV (VPTH) mode. Approaching the final approach fix, you would set the altitude preselector to the MDA. In the CL300/350 PL21, when you dial the altitude preselector down by 1000' increments, it will have an increment that matches the BARO setting on the PFD. I don't know if the CL650 has the same feature, but suspect that it does. In VPTH mode, the aircraft will level at MDA that is set in the altitude preselector. However, there's a problem... If you are descending on the VNAV path in VPTH from the FAF to the runway threshold crossing height, if you level even for a moment at the MDA, you are now above path. if you suddenly see the runway, there is an urge to "go for it", and that's how runway excursions and landing overrun accidents occur. With the constant descent final approach (CDFA) concept, you never level off at MDA. Further, you add a height adjustment to the published MDA to account for the transition from CDFA or VPTH descent to the missed approach climb. In some European States, that height additive is specified by type in the AIP (e.g., France). In other States, it's left to the operator. If you have to determine one, a good rule of thumb is the USAF's 10% of the vertical speed anticipated on final, which is shown on the Jepp charts for the goundspeed expected in the final segment. For 3.0 path, that will be about 60 feet for most CAT C aircraft. A descent path more than 3 degrees may require a larger additive. If you don't apply CDFA in Europe, the approach minimums are increase by a meter equivalent of approximately 1/4 SM for CAT C and CAT D aircraft so that you will see the runway before you get to the nominal 3.0 descent path to the runway. That way, they ensure that you see the runway before the nominal 3.0 degree descent point. No such rule in the US where CDA is encouraged, but it is voluntary. Most schoolhouses teach setting the altitude preselector to MDA (with or with additive) when either on VPTH or level in ALT with VPTH armed when approaching the FAF, then using NAV (LNV) and VNAV (VPTH) to descend and level at MDA. My preference is to fly it like an RNAV (GPS) approach with LPV or LNAV/VNAV minima or an ILS approach. I set the BARO to the MDA plus the additive and then use VGP mode since I'm never going to level at the MDA+additive. When the voice says "minimums, minimums", if the runway is not in sight, it's a missed approach just like LPV, LNAV/VNAV, or ILS approach. This falls into "technique", but it does drive some instructors nuts because they want to show me the system. I want to show them how I'm going to fly the airplane! A VOR or NDB approach is similar; however, the FMS will warn you that it is a REF APPR only, meaning that from the FAF to the missed approach point (MAP), you must have a VOR needle or CDI or at the NDB/ADF needle displayed and that it must also be used for primary course guidance in the final segment. Otherwise, the procedures described above are the same. I don't know if this answered your question, but I hope it helps. Rich Boll

Below is the PVINE3 at KRNO. It is only applicable to runway 34L/R. Those should be the only two runway selections available on the RUNWAYS side of the CDU. Rich

If you select a SID that is applicable to a select set of runways or only one runway, e.g., the RUUDY RNAV SID at KTEB that is applicable only to runway 24, the FMS will only show runway 24. Rich Boll

Thanks Captain! Happy to help, but don't want to be a pain in the backside, either! Rich

errrrrr.... dunno How about that for answer. Where would I check for that? I don't believe so becomes my runways all have slopes. Getting ready to leave the house. Just shutdown Xplane. Will check later tonight.

I noticed that the synthetic vision horizon line is too low at cruise altitude over the central US. I understand that the SV horizon line will vary with terrain and the altitude of the airplane. However, over the central US, in both Collins and Garmin SV systems at FL400/410, the SV horizon line usually sets about 3 degrees below the zero (0) pitch attitude line on the pitch attitude later. I have included three screen shots below. First picture is from Hotstart CL650 over western Kansas. The second and third are from the actual CL350 slightly further west over Taos NM. The PL21 Enhanced SV in the CL350 has the SV horizon line about 3 degrees below the 0 pitch line. Hotstart CL650, it's about 7 degrees below the 0 pitch line. Thought I would pass this along for further investigation. Thanks! Rich Boll

I wish I could. Rest assured that the Hotstart CL650 is about as close as you can get to the real one. I say that with all sincerity. I flew the Zibo mod last night after watching Flightdeck2Sim do a flight from MDW to MSP and back. For fun and try something new, I went back to the Zibo for quick flight from MDW to DTW. I loaded the ILS 27R at DTW only to have to change it to the ILS 22R. I had to delete the entire FLT PLN to change the approach. The Zibo FMS would not let me change the approach from 27R to 22R in the ARR/DEP page. By the time I figured it out, i was high, fast, and well you know the f-word... I have not had that kind of issue the Hotstart FMS. I am picking up some things, like the intercept course discussed above, but that's minor. For an add on that basically new, it's pretty mature right out of the box. Thanks! Rich

Actually, it does. When you select "Vectors" as the approach option, or even if select the full procedure from an IAF or feeder, when you line select the FAF in scratch pad, and then select it to active TO waypoint, the inbound course is preset just like in the Boeings. You then line select the pre-set course and then re-select it to the same position. We call it "make it big" because the number inbound course becomes BIG. I believe that feature is common across all Collins FMS models. Dirty little secret.... in the late 1990s, when Collins was developing their new generation FMS after the colossal flop of their original FMS that went into the Lear 60, they hired a lot of ex-Honeywell engineers to design it. There's a lot of Honeywell Boeing FMS-think in the Collins FMS. I have a 2018 version of the CL650 Advanced FMS book. Here's what it says on 6-6: To intercept and fly a specific course to the airport reference point or runway extension point, enter the course into the scratchpad, then transfer it to the INTC CRS line on the MOD LEGS page. You can use the DIR button or LEGS page. I noticed that Hotstart's implementation is not behaving this way, and I believe that's a bug. Any ideas on how we get this fixed? Thanks, Rich Boll

Depends on how you set up the approach in the FMS. If you plan to fly the full ILS procedure from the IAF or from a feeder fix, the FMS will handle nav-to-nav transfer automatically once APP is selected in the flight guidance panel. Once the localizer comes alive, the system will switch from FMS to LOC, magenta needles will change to green needles. The glideslope will capture normally. If you are receiving ATC vectors for the approach and have selected the VECTORS option when you load the loaded the approach, the process is similar. Once you receive radar vectors, then you can go direct to the FAF waypoint and then select the intercept course option (i.e., make the inbound course in the CRS field big) to extend the RNAV final. When you receive your intercept vector, you may: 1. Select NAV to intercept the FMS magenta line to intercept the inbound course to the FAF. This procedure should be used if you are outside of the localizer SV or are on the fringes of it when ATC issues the clearance. The Collins system has nasty habit of capturing a false localizer. Transport Canada covers this very well in their AIM after a CL604 dang near flew into the side of hill near Vancouver many years ago. I have captured false localizers in Collins-equipped DA2000 and in the Honeywell-equipped Lear 45 in the US after selecting APP mode too early. I have even seen it turn the wrong way and fly outbound if APP is armed at a 90 degree angle to the final approach course. Wait until you are within a 30 degree intercept heading to the final approach course and within the localizer service volume before arming APP. In fact, I will often let the NAV capture the final approach course in LNV and then ARM approach when the FAF is the active inbound fix. This especially true if I have stepdown altitudes prior to the FAF and I need to use VNAV to comply with these intermediate segment stepdown altitudes. These altitudes may be for terrain, airspace (e.g., Class B compliance), or for air traffic separation purposes (e.g., simultaneous parallel independent approach operations). Capturing the glideslope too early, especially on hot days and result in busting those altitudes. Remember, the altimeter reads HIGH when it's warm, while the glideslope is an "iron rail" that doesn't care about temperature. It will take you BELOW those charted altitudes on hot days. Same is true for LPV approaches from the intermediate fix (IF) inbound. I waiting to test a known issue in the Collins FMS in HS CL650, X-Plane, and hot temperatures at KDFW on the RNAV (GPS) approaches. 2. You can select APP Mode when cleared for the approach or cleared to intercept the final approach course. Nav-to-Nav transfer will occur when the localizer capture parameters are met, and the needles will switch from magenta to green. If you are NOT cleared for the approach, you need to switch back to NAV mode to prevent premature glideslope capture and then re-select APP mode when cleared for the approach. This technique is also used if intercepting the localizer for a LOC only or LDA approach. Also, for the reasons above, you need to look out for false localizer captures and make sure that you meet the intermediate segment stepdown altitudes prior to the FAF. Selecting APP mode when cleared for the approach should wait until your heading is within 30 degrees of the final approach course and within in the localizer service volume. On a simple approach with no stepdown altitudes or when receiving vectors at an altitude below these altitudes, this is the easiest. 3. When on vectors, you can manually switch to green needles and select APP mode when cleared for the approach, when the heading is within 30 degrees of the final approach course, and when you're within the localizer service volume. Some folks like to use #3 because they have been bitten by Nav-to-Nav transfer. At 30 NM from the ARP, the Collins FMS will auto-tune the ILS or LOC frequency and set the inbound course in background. If you are unfortunate enough to execute a Direct-To in the FMS at the time that this auto-tuning is occurring in background, there is a chance that the inbound course will not be auto-set. This happened to me once on the LDA Rwy 25 approach into KEGE. We received a Direct-To clearance to QNDRY right as we were at the 30 NM distance from the ARP. While the radios both tuned to the localizer frequency of 109.75, the captain's CDI did not change in background to the inbound course of 250. We used the FMS in LNV and VNAV to laterally and vertically navigate the approach to just prior to WASHI, the FAF, then selected APP mode. I was in the right seat, and my CDI was set to 250; however, the captain's CDI course was set to something else, if I recall 360. Needless to say, we had some last minute changes to make. As result, some pilots (not me...) do not trust Nav-to-Nav transfer and set up the CDI course on their own. There are many different techniques. You may use differing techniques based on the needs of the approach that you're flying and how you're being handled by ATC. Rich Boll