Constant Descent Angle/New Approach Plates

[dougj]

Dear CDA experts: I am to take my IR flight test soon and am having issues with the new CDA method. Under the "Approach Plate" topic someone asked for help on the CYKF NDB26 plate so I'll use that as an example : If you don't have DME or GPS you have no way of knowing where HAMES is, nor do you know where 6.3nm from the MAP is (which is when you would start the descent). If I had DME , and (and after awkward math) I could know that the "6.3nm from the MAP is equal to 7DME, or If I had GPS (again, after the math) that the 6.3nm from MAP is equal to 2.5nm from ZKF. My question is : is everyone doing these approaches doing this awkward math because the nm distances listed in the "Distance/Altitude" tables have no bearing to anything displayed in the cockpit? I was tempted to scroll right on my Garmin 430 (ok I have one) to see distance to nearest airport (hopefully CYKF ) but that only gives me distance to the centre of the airport, not distance to the runway edge (the MAP). Plus the Garmin 430 only gives me distances to the next waypoint on the approach, so it tells me how far to ZKF, not how far to the MAP, so the awkward math would have to be repeated(!) for every entry on the table until past the last waypoint on the approach when the 430 reveals the same numbers as the table.
Plus on another issue has anyone noticed that the new CAPs only have the airport name on the top of the page, preventing the busy IFR pilot from flipping through the pages to find the appropriate page? Someone tell the braniacs you can't flip against gravity.
The closer I get to this rating the further away it appears.
Anyone out there got this figured out?
thanks.

[5x5]

When IFR flying, you always know your destination and therefore the likely approaches you have to choose from. If the math to figure the distances for CDA is tough, do it ahead of time and annotate your approach charts. Also, except for the flight test you are preparing for, there is no requirement to ever use the CDA process. And for your flight test you are likely to be fairly certain the exact approach you are going to be expected to use the CDA method for so there isn't that much preparation required. And as to the flipping through charts issue, again prepare ahead of time. Tear out the charts you want and have them arranged ahead of time in an easily accessed way. Don't carry the whole CAP on your lap when you typically only need a half dozen possible charts.

IFR is all about being prepared. You know exactly where you're going and the route and altitudes to get there, so once prepared IFR is in many ways the easiest flying there is.

[ahramin]

It's simply a matter of figuring out a way to do it that works for you.

I always have a readout of distance to runway threshold right on the fms so I'm used to doing the math in my head in relation to that. If you don't have that option figure out a way of making it easy with what you have. If you aren't used to doing the math in your head, have a 430 and only have distance to next waypoint, then get out your pencil and write down on your chart where you will start your descent and what altitude you should be at relative to distances from each waypoint.

I remember flying with a pilot who simply couldn't keep track of 3 miles per thousand feet. He could initially calculate 20 000' = start descent 60 miles back but in the descent just couldn't do the math. After the second time watching him end up < 3000' 15 miles back I gave him a new rule to follow during descent: Instead of multiplying the altitude by 3 he just subtracted 1000' every 3 miles after top of descent. The easier math made a big difference in descent profile.

[photofly]

I think you're over-thinking things a bit. CDA data isn't supposed to turn a non-precision approach into a precision approach. The distance between the MAP and the centre of the airfield is about half a mile, which is only worth about 160' on a 3° descent. Just make sure you don't go below the MDA. And if you don't have either GPS or DME then it's going to be very difficult to use the distance/altitude table at all: so be it. You had better be timing, too, even if you do have a GPS - there's no overlay on that approach.

The best bit of data you can get from a GPS is an accurate groundspeed: for a normal descent add a zero and divide by 2 to get a sensible rate of descent in FPM (in other words, ground speed in knots x 5). The distance/altitude table is just gravy on top.

[eh3fifty]

Hi dougj,

I have the CYKF NDB RWY 26 in front of me now.

First point: if you told me that you don't have a DME or GPS, I'd start looking carefully at your planning first, to ensure that you have met the required instrument regulations in the CARs for IFR flight. You can do many IFR flights without a DME and IFR-GPS, however, knowing you don't have that equipment it gives me a red flag.

Assuming everything checks out in that department, on to your CDA approach issue.

If you don't have DME or GPS you have no way of knowing where HAMES is, nor do you know where 6.3nm from the MAP is (which is when you would start the descent).

That is correct. You can't do a CDA if you don't know the distance at which to start the descent. You'd do a step down technique in that case.

If I had DME , and (and after awkward math) I could know that the "6.3nm from the MAP is equal to 7DME,

Yes, it's not ideal but it's not too hard. The altitude at 5.7 DME would be 2700, then 4.7 DME at 2380, then 3.7 DME at 2060, then 2.6 DME at 1700. You're adding 0.7 DME to the distances based off the MAP.

There are a lot of numbers but it's actually pretty easy to fly. You're going to fly inbound at 3100 towards the NDB. Once the DME says 7.1 - 7.3 (add 0.1-0.3 to account for transitioning into the descent smoothly) you'll gently enter a descent. The nice table in the lower left of the plate says you should be descending at 580 fpm for 110 knots over the ground. Note - if you're in IMC and entering a descent, be very gentle. 580 fpm will come quick and it'll be very easy to overshoot that target! Now peg your VSI at 580 fpm.... PEG IT! TRIM. TRIM. PEG IT! TRIM. You've pretty much got the approach nailed now. Look at the DME and watch for 5.7. A quick glance at your plate tells you to be at 2700. As you approach 5.7 you'll already have a good idea if you're too high or low. Fix it. Then next mile. And so on. Takes a bit of practice but it's not that bad. It'll feel really good when you can fly it proficiently and break out of the clouds to see the PAPI giving you two white and two red lights.

So, in summary: if you enter the descent at the proper distance and then peg your VSI for your ground speed, you pretty much have it made. A quick glance at the plate throughout the approach tells you if you're high or low and you can make a small correction to fix it. Runway in sight, land.

Oh, and remember your cold temp corrections! Don't you wish you had an FMS?

As far as cold temp corrections, I calculate them myself. I'll get the distance from threshold and plug this into my calculator: 318' x 1.10 (-10 degrees C correction) = 350' / NM. Note - 318' / NM is equal to a 3 degree path.

Now take your threshold elevation: 1240' ASL + 50' (threshold crossing height) = 1290' + 350' = 1640' (1 mile back), +350' = 1990' (2 miles back), +350' = 2340' (3 miles back).

I just got the altitudes for the doing a 3 degree descent from circuit altitude. I do this for VFR approaches, especially at night, but even during the day for practice and to get that 3 degree path image burned in my memory. This takes me 15 seconds to do and it works like a charm! Get a calculator that adds the last amount to the sum every time you press the equals button - helps a lot.

-20 degree C correction is 15%, -30 degree correction is 20%. This will error on the side of caution - you'll get the exact altitude for the temp or you'll be slightly high.

If I had GPS (again, after the math) that the 6.3nm from MAP is equal to 2.5nm from ZKF.

If you had a GPS I would do it the same way as the DME - get distances on your GPS off the YWT VOR. Add 0.7 to all the chart distances for the CDA.

[photofly]

Today I spoke to a respected and senior Pilot Examiner about this approach - the NDB RWY 26 at CYKF. He said without DME or GPS he would - and one should - be able to be confident about being inside HAMES (3.3 from ZKF) purely by timing the outbound and inbound parts of the procedure turn and estimating ground speed and winds.

[DanWEC]

Photofly, you beat me to it regarding the outbound timing. While I'm not senior, and certainly not respected, , that is the only way to do it with minimal equipment.

Take a look at the NDB A approach into CYND. There is no DME, hell there isn't even a FAF, yet there IS a CDFA. The only way to estimate your descent point is by getting distance by estimating GS and timing outbound and inbound.

As a note about the CDA, I've added it to my approach briefing, and that's the way I teach it as well. I use the top down method of brief, and as I'm talking about the inbound track, now I also state where (either with dme, or calculated gps distance from faf/next waypoint if with GPS) I will start my decent at xxx FPM using the chart.

The CDFA is a nice addition, though I've always used a stabilized descent anyways when I could, it just takes the mental calculation out of it.

[photofly]

Photofly, you beat me to it regarding the outbound timing. While I'm not senior, and certainly not respected, , that is the only way to do it with minimal equipment.

Take a look at the NDB A approach into CYND. There is no DME, hell there isn't even a FAF, yet there IS a CDFA. The only way to estimate your descent point is by getting distance by estimating GS and timing outbound and inbound.

Same with the NDB RWY 05 at CYOO.

An interesting point about the NDB A CYND. It's a circling approach, and according to some TC document or other, CDFA is only given for straight-in approaches. But there's the data...

[Flying Low]

I guess things have changed since I did my initial instrument rating. We were always taught that you have to be able to prove your position before descending to the next lower altitude. In this case (without DME) it would be 3100' to YKF and then drop for minimums. At a descent rate of 1000'/min at 120 knots ground speed you are basically on a CDA and your descent rate is still manageable.

[DanWEC]

I guess things have changed since I did my initial instrument rating. We were always taught that you have to be able to prove your position before descending to the next lower altitude. In this case (without DME) it would be 3100' to YKF and then drop for minimums. At a descent rate of 1000'/min at 120 knots ground speed you are basically on a CDA and your descent rate is still manageable.

That's precisely why the step down method is being heavily frowned upon, to avoid major stabilization changes during approaches that have been proven to contribute to CFIT.

[Flying Low]

I am a big fan of the CDA method for exactly that reason. I do, however, have a big problem descending without positive proof I am in the protected area. In most aircraft nowadays it's pretty simple with GPS but if you are doing the NDB approach with only a NDB then you have no choice but to stay at 3100 until you go by the beacon.

[eh3fifty]

He said without DME or GPS he would - and one should - be able to be confident about being inside HAMES (3.3 from ZKF) purely by timing the outbound and inbound parts of the procedure turn and estimating ground speed and winds.

Take a look at the NDB A approach into CYND. There is no DME, hell there isn't even a FAF, yet there IS a CDFA. The only way to estimate your descent point is by getting distance by estimating GS and timing outbound and inbound.

Unbelievable. I'm a little shocked to say the least. Let me explain.

You should be confident you're inside HAMES purely by timing? That's beyond ridiculous. Here's some simple math. Let's say you miscalculate by 0.5 NM based on timing (that's incredibly conservative - anyone who's actually flown an approach on timing in IMC should know that) - where do you think that'll put you? Well, you guessed it... 0.5 NM beyond the threshold, at 50' above threshold elevation. That will move your touchdown point more than 3000' beyond where it should be. How long is your runway that you're approaching too? Let's hope it's at least 5 miles long if you're going to do that method. What if you're 1 NM off because you didn't accurately estimate the wind at altitude because you have no way of doing so?

Unbelievable. If an examiner gave me a 2 because I did a step down technique for the CYKF or the CYND approach I would be taking it to the Transportation Appeal Tribunal of Canada. I wouldn't accept that reason - even though I didn't fail that exercise. It's a safety hazard to tell pilots to descend on a 3 degree and expect the runway right where it should be when they have no positive indication of their position.

I'll discuss two different NDB approaches: one where there is a FAF and one where there isn't a FAF.

Case 1 (there is a FAF - CYKF NDB RWY 26): the danger in descending on a 3 degree prior to the FAF is that you can easily go through 2200 because of a miscalculation of distance using timing and a roughly estimated ground speed. Yes, you can say that you are always to monitor until passing ZKF NDB prior to descending to the MDA. I would counter with the argument that I will then start my descent as soon as I intercept the inbound course, and I will descend at whatever VSI is required for a 3 degree, to the altitude of 2200. The key difference is that I'm not descending on "a 3 degree path to the runway", I'm descending at say 700 fpm to an altitude of 2200. The latter being the safer method in this case. Putting in your mind that you're on a 3 degree path to the runway can easily distract you into trying to maintain the required rate instead of insuring that you're meaning to level at a particular altitude.

I will only fly a 3 degree path if it leads to the runway. If I can't be assured that the 3 degree path will lead to the runway, I will NOT descend on a 3 degree path. I will descend at a certain rate to a certain altitude.

Case 2 (there is no FAF - CYND NDB A): there are two ways I see this going (other than guessing accurately your descent point as a fluke - assuming no GPS or DME). 1) You descend prior to the point at which you should, and 2) you descend after the point at which you should. In #1, you will be descending at a specified rate for the 3 degree based on what you think your GS is and you'll be targeting the MDA altitude - again assuming that you will be breaking out with the runway in the correct 3 degree position. This case is similar to the one where there is a FAF - you could be more focused on descending at your required rate instead of focusing on levelling at the MDA altitude. Same solution, start down immediately after intercepting the inbound course at a moderate rate consistent with a 3 degree path for your airplane and target your level off at MDA. In #2, descending beyond the point at which you should will also put you at the same risk as you would have in #1 as well as putting you beyond the point at which you'd be able to make a straight in landing or beyond the point at which you'd be able to circle. Neither case is desirable and should result in a go around. You've now wasted fuel by flying a poor approach. This could easily have been avoided by descending to MDA as soon as established inbound at a rate consistent with a 3 degree path.

When you are circling to a runway with an ILS approach (for the opposite side) do you fly the ILS or the LOC approach? You should be flying the LOC approach. The whole reason being that you are established in level flight with the airplane trimmed at the MDA before the advisory visibility so that you give yourself the best chance of seeing the runway and to be in a good position to circle. Flying the ILS to circling minima is NOT safe on an ILS (where you KNOW your exact position) because you won't be in a stable state when you start the maneuvering for circling, and it is DEFINITELY not safe when you do NOT know your exact position!! This will put pilots in positions where they see the runway at the last second (again, in an unstable aircraft state) and tempt the pilot to circle. This is dangerous!

This is no different than attempting to do a 3 degree path for a circling approach where you do not know your distance. Even if you're on your proper 3 degree path you still are no different than flying a 3 degree ILS to circling mins as I described in the paragraph above. But if you are beyond the proper 3 degree descent distance you will be closer to the runway when you break out and this will further add a complication to your circling maneuver.

This all could be avoided by descending to the MDA as soon as inbound to the MAP when there is no FAF.

The 3 degree CDA is PERFECT for an aircraft equipped with distance measuring equipment, be it DME or GPS, but it can put you in a dangerous position if you attempt to fly a 3 degree CDA when you do NOT know your exact position!!

I do, however, have a big problem descending without positive proof I am in the protected area.

Me too! I have a big problem descending when I don't know exactly where I am!!

Like I said, I will definitely be taking this to the tribunal if I ever do get assessed a 2 because I didn't do a CDA when I had absolutely no way of determining my distance from a known point on the approach. I doubt that will ever happen as I fly aircraft with a good set of navigation equipment but I will definitely come to another pilot's aid if they are ever scolded because they didn't descend on a CDA when they didn't know exactly where they were.

[DanWEC]

Case 1 (there is a FAF - CYKF NDB RWY 26): the danger in descending on a 3 degree prior to the FAF is that you can easily go through 2200 because of a miscalculation of distance using timing and a roughly estimated ground speed. Yes, you can say that you are always to monitor until passing ZKF NDB prior to descending to the MDA. I would counter with the argument that I will then start my descent as soon as I intercept the inbound course, and I will descend at whatever VSI is required for a 3 degree, to the altitude of 2200. The key difference is that I'm not descending on "a 3 degree path to the runway", I'm descending at say 700 fpm to an altitude of 2200. The latter being the safer method in this case. Putting in your mind that you're on a 3 degree path to the runway can easily distract you into trying to maintain the required rate instead of insuring that you're meaning to level at a particular altitude.

I will only fly a 3 degree path if it leads to the runway. If I can't be assured that the 3 degree path will lead to the runway, I will NOT descend on a 3 degree path. I will descend at a certain rate to a certain altitude.

Case 2 (there is no FAF - CYND NDB A): there are two ways I see this going (other than guessing accurately your descent point as a fluke - assuming no GPS or DME). 1) You descend prior to the point at which you should, and 2) you descend after the point at which you should. In #1, you will be descending at a specified rate for the 3 degree based on what you think your GS is and you'll be targeting the MDA altitude - again assuming that you will be breaking out with the runway in the correct 3 degree position. This case is similar to the one where there is a FAF - you could be more focused on descending at your required rate instead of focusing on levelling at the MDA altitude. Same solution, start down immediately after intercepting the inbound course at a moderate rate consistent with a 3 degree path for your airplane and target your level off at MDA. In #2, descending beyond the point at which you should will also put you at the same risk as you would have in #1 as well as putting you beyond the point at which you'd be able to make a straight in landing or beyond the point at which you'd be able to circle. Neither case is desirable and should result in a go around. You've now wasted fuel by flying a poor approach. This could easily have been avoided by descending to MDA as soon as established inbound at a rate consistent with a 3 degree path.

I definitely see your point- however, you just use good judgement for whatever approach you're doing given the equipment, that's it. Everything else delves into semantics.
Realistic question- how often do you have NO idea about the winds at your destination? Given FD's and all that...
Also, I would say that descending at ~500 FPM stabllized, and leveling off for a half a mile while at the MDA is better than diving down at 1000 FPM and dragging yourself for 4 miles in landing config. Well, at the least it's more elegant, I'd freaking hope most of of can hold straight and level in approach config- but... given the choice?

But again, it's all about judgement, I think both you and I would elect to get down to MDA likely a little bit sooner and look for the runway on a donkey dick of an approach like one of these. I'm just saying the CDA is a helping hand to get it done in a MORE stabilized manner which I think we can agree is safer, in accordance with all other circumstances!

Point of contention however- if, as you mentioned, focusing on a constant rate of descent can distract a pilot and blow through minimums, that pilot has some work to do before being competent in IFR wouldn't ya say?

Cheers
D

[eh3fifty]

Realistic question- how often do you have NO idea about the winds at your destination? Given FD's and all that...

Sure you can have a general idea but as I pointed out, if you're only 0.5 NM off then that'll put you more than 3000' beyond your touchdown point. You can put the nose down once you break out and try to fix being high but now you just destabilized your approach. The whole point of the 3 degree CDA is to eliminate unstable approaches as they significantly increase the risk of a CFIT.

I'm just saying the CDA is a helping hand to get it done in a stabilized manner which I think we can agree is safer, in accordance with all other circumstances!

You said previous to this that you would use good judgment too in deciding how to fly the approach. And I fully agree! The good judgement in my view is that you will fly a step down technique when you don't have the DME or GPS distance you require to fly a proper 3 degree to the runway. My point is that if examiners are marking students down to a 2 (which is a major error) because they don't do the CDA in these particular cases, that is a major safety issue!

if, as you mentioned, focusing on a constant rate of descent can distract a pilot and blow through minimums, that pilot has some work to do before being competent in IFR wouldn't ya say?

No, I don't think so. Are you going to do your flight test when there's moderate icing forecast all around the province, coupled with low ceilings? Probably not. Now add in another aircraft approaching the same airport for the approach and a malfunctioning TAWS that is giving you erroneous warnings when you're more than 2000' AGL - the AFM supplement telling you to pull the TAWS CB in that case. I'm not talking about a flight test or training here - I'm talking real world. There's a lot of issues that can pile on to you and consistently shooting a CDA approach is a major setup for an accident. I've had some learning experiences, like every single operational pilot in Canada has had or will have, if they just started out. Luckily, I haven't had to learn from a crash or loosing 2 feet of wing to a tower. My big issue with this is that the overall risk (considering pros and cons) of the CDA where you don't know your distance is greater than the overall risk (considering pros and cons) for a step down technique.

[photofly]

Gosh. Lots of words.

I imagine he has something like this in mind: fly the procedure turn: one minute past the beacon, 45 degrees to the left for 45 or 60 seconds, according to taste, and then a right one-eighty to intercept the inbound course. With an airspeed of 80kts, and 20kts of headwind, you're now inside 3.3 miles. Drop down to 2320 and start a 3° descent crossing ZKF.

[eh3fifty]

photofly..

If you're going to do that you might as well drop down an extra hundred feet to 2200 and then when you cross the NDB drop down to the MDA. What you've described is no different than the step down technique.

The purpose of the CDA is to have one descent on the final approach course that takes you on a stable 3 degree path to the runway.... not two descents, or three, or more.

If you're not going to follow the CDA published on the chart then I recommend you do not follow it.

As far as doing it your way, you'd be high if you started your descent from 2320 after crossing the NDB. To intercept the 3 degree accurately you'd have to start a certain altitude below 2320. But that's beside the point - you're doing a step down technique. Just because you're descending at a rate consistent with a 3 degree path does not mean you're doing a CDA.

[FenderManDan]

This topic is, coincidentally, interesting. This Sat Ill be at CYND and I will try that NDB approach to circle if need be. Next week I am doing YKF ILS and other approaches for practice so this topic nails some of my head scratching.

First time going to YND, any recommendations (DanWEC)?

Cheers

[eh3fifty]

photofly..

Same with the NDB RWY 05 at CYOO.

How would you determine where/when to descend on this approach to follow the published CDA without DME or GPS distance?

[eh3fifty]

An interesting point about the NDB A CYND. It's a circling approach, and according to some TC document or other, CDFA is only given for straight-in approaches. But there's the data...

I'm not sure where you got that from, photofly, because the TC Advisory Circular on CDA approaches actually uses a circling only approach as an example of where the CDA procedure is published.

https://www.tc.gc.ca/eng/civilaviation/ ... -1751.html

If you have distance information, you can fly the published CDA and if you break out before or at the MDA you can continue on that path to the runway.

[photofly]

I take your point about circling approaches; I had over-interpreted a line in the flight test guide.

AC 700-028 defines both a CDA and SCDA approach as a constant angle of descent from passing the FAF. Clearly you can have as many level flight segments as you need before then, to descend for the PT, for example, or to step down to an altitude from which you wish to begin the CDA. I prefer their definition to yours.

[eh3fifty]

AC 700-028 defines both a CDA and SCDA approach as a constant angle of descent from passing the FAF. Clearly you can have as many level flight segments as you need before then, to descend for the PT, for example, or to step down to an altitude from which you wish to begin the CDA.

That AC says: "The descent shall be flown to pass at or above the minimum altitude at any step-down fix. This technique involves achieving a constant angular descent profile from the FAF, or optimum point on procedures without a FAF, to a reference datum above the runway threshold (typically 50 ft.)."

The reason they say from the FAF is because the whole stabilized approach criteria has always defined the FAF as being the point at which you need to be stabilized even before SCDA and other types of stabilized approach guidance was made. When you flew the ILS you were told to be stabilized at the FAF with a constant descent rate and constant speed.

As I pointed out above, your technique of descending to the FAF crossing altitude and then to the MDA is essentially a step down technique.. except you have a good chance of screwing up the entire approach because you descended too late or not at a high enough rate because of your inaccurate estimates and now you're not in a position to land. Or are you going to push the nose down to make the runway? That defeats the entire purpose of having a stabilized approach! Go around. You just wasted some precious fuel. 10-15 minutes of fuel wasted. Next time I'd recommend you do the proper step down technique so that you're in a position to land when you see the runway.

Let's say you did have distance info and you still did it your way instead of starting at the recommended altitude for intercepting the CDA. Doing it your way you only have 1 point to check your altitude and figure out if you're high or low before you reach the MDA. That is not a lot of time or chances to correct your glide path. If you did start it at the recommended altitude of 3100 for the approach, you'd have 3 solid points to check your altitude against what it should be (4 points if you count the FAF crossing altitude). This gives you a decent chance of getting stabilized in a descent in IMC and actually being on the 3 degree slope you're supposed to be on.

As I said before, if you're not going to do the CDA as laid out on the plate, don't attempt to make up your own CDA. There is a reason they have a recommended altitude on the plate... I recommend you follow the recommended CDA profile!

Another example: NDB RWY 05 at CYOO. The recommended CDA starts at 5.6 miles and 2200 feet. But there is a 4 mile and 1700 point on the 3 degree path... wouldn't that be easier to remember and use? No! Why? Because of all the reasons I've already stated. 1) You're doing an unnecessary step down descent which is defeating the purpose of a stabilized constant descent approach! 2) You now only have 1 check point to ensure you've intercepted the 3 degree path accurately. And I forgot to mention, you have a higher chance of busting your MDA because you have less time to stabilize in the descent before the MDA - you could still be focused on flying and trimming the airplane instead of watching for the MDA.

Follow what's depicted on the plate. If you don't have distance info then you shouldn't do a CDA. By now you should see why a step down technique is actually simpler and safer in that case.

[Big Pistons Forever]

If you are flying a large aircraft with 2 crew then CDA is the only way to go. The PNF can keep track of the distance vs height and the PF can adjust the descent rate accordingly. Dive and drive in a large aircraft with lots of inertia and slow spool up times is a good way to get into trouble, as has unfortunately been demonstrated in many accidents.

But small airplane single pilot, I think CDA is often an unnecessary complication. Before the recent CDA fetish I told my students to start a slow descent as soon as they were nicely established on the inbound track. They then watched the GPS /DME distance to the FAF. If it looked like they were going to get to the FAF crossing altitude before crossing the FAF ease up the rate of descent, if they are high increase it. Once past the FAF establish a good rate of descent because you want to get to the MDA, get visual, see the end of the runway and set up for the landing. I also told them that if you did not have a good visual picture of the runway landing environment as soon as you reach the MDA, you should immediately start the missed approach.

That is the difference between real world IFR and passing the IFR flight test........

[kev994]

I also told them that if you did not have a good visual picture of the runway landing environment as soon as you reach the MDA, you should immediately start the missed approach.

Strongly disagree. I've broken out horizontally a number of times. No need to start the missed until the MAP if you're using the 'dive and drive' method. TERPS data is based on it. If you start the missed early you still need to follow the horizontal profile of the approach to the MAP to get your obstacle clearance assurance, and then switch to the missed approach instructions... seems unnecessarily complicated.

Edit: to clarify "using the dive and drive method"

[eh3fifty]

If you are flying a large aircraft with 2 crew then CDA is the only way to go. The PNF can keep track of the distance vs height and the PF can adjust the descent rate accordingly. Dive and drive in a large aircraft with lots of inertia and slow spool up times is a good way to get into trouble, as has unfortunately been demonstrated in many accidents.

I completely agree... but only if you have the appropriate distance info as I have exhaustively explain in my previous posts. I fly two-crew non-precision approaches using step down technique all the time... like many other pilots. It is not as safe as flying a CDA but, again, only if you have the equipment to do so. Otherwise it's actually an increase in workload which is NOT safe when near the ground and in that case I argue it's more dangerous than the step down technique. Big jets have the equipment to do this all the time and consistently. An FMS or G1000 type avionics is perfect for doing CDA approaches safely every time.. unless you need to circle or because of another operational factor.

In the two-crew airplane I fly we have GPS and we have this distance info to fly the CDA properly. I fly them when they're appropriate and I'm a promoter of the CDA technique. But I can't say this enough... they are not always appropriate!!!

I also told them that if you did not have a good visual picture of the runway landing environment as soon as you reach the MDA, you should immediately start the missed approach.

Like kev994, I also disagree with that.

If you descend steeply and end up before your advisory visibility point for the 3 degree path, you shouldn't have a "good visual picture of the runway landing environment". You should continue at MDA until you're in the right position to descend from the MDA. By automatically doing a go around at MDA when you're not following a well defined CDA, you're wasting an approach and that approach could mean a lot to you when this happens to be your alternate and you're a little low on fuel. You go missed on that one and the stress level is even higher now because you know that you're getting lower on fuel. Do you think you're going to fly the next approach as well as the last one now that you are more stressed?

TERPS data is based on it.

Kev994, we don't use TERPS in Canada. The document for approach design in Canada is the TP 308. The FAA uses TERPS.

If you start the missed early you still need to follow the horizontal profile of the approach to the MAP to get your obstacle clearance assurance, and then switch to the missed approach instructions... seems unnecessarily complicated.

It's really not complicated. I see nothing wrong with doing a go around before the MAP especially if you're around mountainous terrain. If you see the runway and realize you're not in a position to land or circle then there is no reason to keep trucking at MDA until you get to the MAP. If I have distance info (which I always do) I will usually start a go around a mile back from the MAP because I know that even if I see it now, I'm not going to make it in. Then once I reach the MAP I'll start the missed approach. The go around is a transition to a climb away from the ground; a missed approach is a defined lateral and vertical path to follow after reaching the MAP.

[Big Pistons Forever]

I also told them that if you did not have a good visual picture of the runway landing environment as soon as you reach the MDA, you should immediately start the missed approach.

Like kev994, I also disagree with that.

If you descend steeply and end up before your advisory visibility point for the 3 degree path, you shouldn't have a "good visual picture of the runway landing environment". You should continue at MDA until you're in the right position to descend from the MDA. By automatically doing a go around at MDA when you're not following a well defined CDA, you're wasting an approach and that approach could mean a lot to you when this happens to be your alternate and you're a little low on fuel. You go missed on that one and the stress level is even higher now because you know that you're getting lower on fuel. Do you think you're going to fly the next approach as well as the last one now that you are more stressed?

.

First of all a correction. I should have said if upon reaching the MDA you don't have the runway environment in sight then you should go around. The missed approach part of the approach starts at the MAP so you have to go to the MAP before you start the miss approach procedure. However if you go around early you will be higher than the MDA at the MAP and this is always safer.

For the majority of non precision approaches, especially those in hilly terrain the MAP will be so close to the end of the runway and/or so high a straight in landing from the MAP is not safely executable, so unless you are at circling minimums there is no point in going to the MAP before starting a go around. If you are planning to circle in crap weather then be aware that you are 8 times more likely to kill yourself than if you flew a straight in approach......

This is a training forum and the original poster appears to be a new IFR pilot. Single pilot at the MDA and then trying to fly the airplane and look for the runway in the goo ahead is how new IFR pilots kill themselves. Most of the time in the real world at or before reaching the MDA, you break out of the clouds and see the runway. Since you did the dive part you will be well back from the threshold and can transition to a normal visual approach path and land. Get to the MDA and sort of, kind of, see some ground but no sign of the runway......time to get the hell out of there.

Finally for all IFR pilots, but especially the new ones, crap weather at your destination is not the time to be tight on fuel