Non-precision approaches and descent planning

  • Thread starter Thread starter Roger, Roger
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ClearedToThe said:
If hand flying, the stair step is easier IMHO.

If you are flying the approach on autopilot, set in the published rate of descent from the plate and select vertical speed mode on the autopilot when crossing the FAF and have the altitude selector set to the MDA rounded up to the nearest 100ft. Of if your autopilot can handle altitudes in 10' incriments, set a DDA (Derived decision altitude). DDA = MDA + 50ft. This is a CANPA, as previously mentioned, and works extremely well if executed properly (even in a 172) and IMHO is much safer than the dive-n-drive. Not to mention passenger comfort.
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The problem with autopilot is...most of our planes don't have it. The autopilots that are installed (KrAP 140) are a) not authorized for single-engine operations and b) not authorized to do altitude captures below 800' AGL.
 
Fly_Unity said:
I favor the stair step approach mostly cause in the mountainous areas the approaches are pretty steep and I like to be as low as possible because its hard for me to slow down and keep engine temps warm doing the whole descent at once. Also in my experience Its better to get low and out of the ice as fast as possible, I always found that clouds tend to have more moisture at the tops. Depends on the day, and the area. I'm not used to see FAF altitudes lower then 7 thousand either. I guess I never had a problem having to keep leveling off at every fix, I'm usually struggling to get down by the fix without busting everyone eardrums
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While he is speaking of mountain flying here and I believe for most of us that can be ignored, there is a real good point here. Note the get out of the ice in bold, I noted that because I believe both methods should be taught. The method you use is completely up to you as PIC, if you have to worry about engine cooling maybe you want to step down. If there is an inversion layer with possible icing below you then maybe you want to shoot through. I wasn't taught one or the other, I had instructors that said one and others that liked the other.

Ultimately though I think it is better to teach both and give some practical simulations that will require judgment and decision of which to use. Learning the first method also has the benefit of teaching the student to stay further ahead, but knowing the second method exists can be used as a backup should the pilot be a little overworked that day and might not be able to quickly enough calculate the descent in his/her head.

Point is, both work, both are safe, and both are viable options which if the student is taught how to evaluate situations these become resources for them.
 
shdw said:
Point is, both work, both are safe, and both are viable options which if the student is taught how to evaluate situations these become resources for them.
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Who are you and what have you done with Shdw?.....:D
 
Why re-invent the wheel? It's a non-precision approach and there is a staircase descent that is published. This takes all the guesswork out of how and when to descend and eliminates the need to do bogus calculations while you're in the soup and should be worrying about more important things than "how to make your Non-PA into a more precision-like approach". I suck at the quick calculations and knowing me, I'd probably get confused and just go missed once or twice until I finally gave up and followed the staircase method. I just do what I'm told and try not to have any ideas of my own :laff:
 
Orange Anchor said:
And if the MAP is at the end of the runway, take about :30- :45 seconds off the timing since one goes from a normal glide path to a 90deg path using a 700fpm descent.

The other point is yes, the studies showed that the average airline pilot made 1-3 NPAs (as I remember) per year. For that reason many airlines first did away with NDBs. Many have deleted VORs.

But your procedures are not uncommon (app flaps, gear down) and at 400-500ft changing config, power and trim. And no one seems to notice the disconnect over stable approaches. And why? Because statistically it can be supported... until the first big accident.
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I guess I'm confused at what you are saying regarding "common procedure".... I take what you're saying to mean that inside the FAF, quite possibly once reaching MDA, the crew makes the final configuration change. I was merely pointing out that we are fully configured to land prior to the FAF/descent to MDA.
 
cencal83406 said:
I guess I'm confused at what you are saying regarding "common procedure".... I take what you're saying to mean that inside the FAF, quite possibly once reaching MDA, the crew makes the final configuration change. I was merely pointing out that we are fully configured to land prior to the FAF/descent to MDA.
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Yes. Landing flaps upon seeing the runway/runway environment and as we used to do, announce "Landing". At that point call for landing flaps and finish the Landing checklist.

For a while, we were actually configuring with landing flaps in the 737 just prior to the FAF and doing the D&D to MDA and leveling off. That took around 3500/4000lbs per engine. And yes, it was a while back. We also used that procedure in the 727 and that was Fuel Flow times three.

(going even farther back, in the KC-135 we did the dive and drive and that was the old J-57 and you REALLY ate up some serious fuel with gear down and flaps 50. We had a high TACAN approach to Alpena MI which was a joint use field. The app is still there. WOW...)

http://204.108.4.16/d-tpp/0904/00718HVDT1.PDF
 
What exactly is the point of a HI-ILS or HI-TACAN? I see that they have much higher initial altitudes than your normal, and I know they're military-related, but I don't understand the reason for publishing them.
 
Roger said:
What exactly is the point of a HI-ILS or HI-TACAN? I see that they have much higher initial altitudes than your normal, and I know they're military-related, but I don't understand the reason for publishing them.
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Mil jets need to descend out of the high environment (called a Jet Penetration), since they can't hold well down low for any number of reasons. The high environment transition is known as a Penetration Track (the dotted portion). These IAPs provide good flow from the high environment to the field without requiring any ATC vectoring, that would come with standard approaches or getting down into the low environment, and are normally optimized for Approach Category E aircraft, who can't shoot many low-altitude IAPs anyway. For flow of multiple formations of fighter-type aircraft into a field, you additionally have ASLAR HI procedures (Aircraft Surge Launch and Recovery), which are HI procedures that incorporate Drag, Decel, and Final Approach Speed points on the final segment for formation breakup.
 
Roger said:
I just talked to one of our TRACON guys. He said that that last altitude, the minimum altitude until course intercept, is basically a suggestion/notification of the minimum vectoring altitude, so in this case it is essentially pilot's discretion whether or not to descent to that altitude immediately. Basically if they want you lower, they'll notify you.
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It's the use of the phrase "...maintain 3,000' until established..." that would confuse me based on that opinion. That's not "N12345 pilots discretion, descend and maintain 3,000' until established...".

I'm wondering how he would feel if he gave me "N12345, climb and maintain 15,000" and I hung out down at 3,000' for a while?

-mini
 
minitour said:
It's the use of the phrase "...maintain 3,000' until established..." that would confuse me based on that opinion. That's not "N12345 pilots discretion, descend and maintain 3,000' until established...".

I'm wondering how he would feel if he gave me "N12345, climb and maintain 15,000" and I hung out down at 3,000' for a while?

-mini
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I agree that it does seem a bit non-standard. However, I understand the use of "maintain 2400" in this context to be different from "descend and maintain 2400". One contains instructions to start a descent, the other does not. However, the instructions would be clearer if they said "Turn right heading 340, maintain at or above 2400 'til established, cleared VOR-DME 31".

Perhaps this should be made a topic in the "Pilot-Controller Questions".
 
Orange Anchor said:
Nice.. what? the trick is the losing 7000ft from the 11DME to be below 8000ft at the 020 radial on the arc. figure 240kts so 4miles/min.. 5miles to the arc, 7 miles to the 020...12 miles would require a 3000fpm descent to make the restriction, right?

Definitely a ground brief before flying.
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http://204.108.4.16/d-tpp/0904/00354HI21.PDF

Oh yeah.....definite one you'd like to ground brief if you could.

Just to demonstrate how much of a royal pain in the ass this IAP was, esp single pilot and in the WX, wanna run through it. You math guys will love this one. For you OA, this could be a good AFR 51-37 refresher for you! :D

First, we have to establish the ground of what one had to deal with when flying this. In the old F-117 I used to fly, our jet penetration speed was 300 kts, and we had a 14 CFR 91.117d exemption for it. The jet didn't like maneuvering when much slower than that due to the permanent 72.5 degree wing sweep. The jet was single pilot, had no flaps, had no speed brakes, and only 1 NAV radio and 1 UHF Comm radio, however the HSI has an RMI function within the instrument.

The biggest thing with flying these kinds of approaches...the full approach....is knowing your numbers well ahead of time for performance. In a light GA aircraft, you can wait until you're nearly on an arc or about 0.5nm from it before you start your turn; and similarly, you can wait until after the CDI comes alive before turning from an arc to a radial. Not so in a fighter. At 300kts, you do any of these, and you're going to WELL overshoot any radial/arc. So this is where a little bit of public math comes in known as the 60 to 1 rule.

For fast aircraft, knowing when to turn to intercept an arc/radial is key. Using 60-1 I can easily figure this out.

First, radial to arc:

radial to arc: Turn Radius equals Indicated Mach Number minus 2. Therefore TR=IMN - 2; or mach minus 2, where mach equals miles per minute. In my case, 300 knots equals 5 miles per minute. So 5 minus 2 equals a 3 mile turn radius to make a 90 degree turn; ie- lead the radial to arc by 3 miles.

Now arc to radial (need to compute a Lead Radial):

arc to radial: 60 to 1 rule. 60/DME arc x TR, DME arc distance divided into 60, multiplied by Turn Radius. So, on a 15 DME arc (yes, I know it's 16 for this IAP, but for sake of public math ease), 60/15 equals 4....times 3 (TR) equals 12. Or make the lead radial 12 degrees short of the desired radial.

Yes, it's public math, but it's pretty simple public math that can be figured out in pre-mission planning, or enroute.

Now getting to the IAP. Am inbound at 300kts on the CME R-080 at at/above 15,000, Channel 108 tuned in and headed for JENOM (IAF). Crossing JENOM, continue inbound on the R-080 until 5 DME, where I have to start my right turn to intercept the CME R-360 (Gotcha #1). Continue outbound on R-360 to begin the right turn to the arc at no later than 13 DME due to radial-to-arc needs(Gotcha #2). Have to simultaneously begin a descent from at/above 15,000 to at/below 8000 while turning onto the arc (about 3500+ fpm descent....normal to what many Jet Penetrations are planned for), and have this completed prior to crossing CME R-020 (Gotcha #3)....because when crossing R-020, I now have to make a descent to a hard-alt 6500 for LOC intercept (Gotcha #4). I await the Lead Radial of 043 (round it to 040) from CME to begin the turn to intercept the LOC (Gotcha #5). Crossing the LR, I have to quickly change from CME to the LOC freq I-ROW Ch 36 ...(big Gotcha #6).....double check the morse code....and set the inbound course of 215 into the HSI, to where I should see the CDI already off the case by this time (halfway through the turn), and maneuver to intercept it. Drop the landing gear, perform final landing checks, slow to 180 (or computed basic weight + fuel + ordnance + 1/2 crosswind gust component), and descend to at/above 5400 when tracking the LOC (no need to be centered up, just intercepting) in prep for glide path intercept. No frequency change to tower should be necessary, since SFA procedures are in effect when IMC. Have no ADF to identify TOPAN, nor do I have CME tuned up anymore, so DME is all that's available. Intercepting the GP and crossing 7 DME, crosscheck the glideslope check altitude and run through the 5-Ts, noting timing for 180 kts, or interpolating for 190 kts; and proceed down the GP to the DH of 3837 (3900)...noting the other MDAs in case a transition to non-precision is needed. Once breaking out and transitioning to visual, land; throw out the drag chute if less than 15kts x-wind, slow and exit the ruway.kicking the chute off before pulling off.

All of this while in the soup, and single pilot...with the aircraft limitations listed above.

Talk about a nice mental workout.
 
Roger said:
I understand the use of "maintain 2400" in this context to be different from "descend and maintain 2400".
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AIM 4-4-10

d. When ATC has not used the term "AT PILOT'S DISCRETION" nor imposed any climb or descent restrictions, pilots should initiate climb or descent promptly on acknowledgement of the clearance. Descend or climb at an optimum rate consistent with the operating characteristics of the aircraft to 1,000 feet above or below the assigned altitude, and then attempt to descend or climb at a rate of between 500 and 1,500 fpm until the assigned altitude is reached. If at anytime the pilot is unable to climb or descend at a rate of at least 500 feet a minute, advise ATC. If it is necessary to level off at an intermediate altitude during climb or descent, advise ATC, except when leveling off at 10,000 feet MSL on descent, or 2,500 feet above airport elevation (prior to entering a Class C or Class D surface area), when required for speed reduction.

e. If the altitude information of an ATC DESCENT clearance includes a provision to "CROSS (fix) AT" or "AT OR ABOVE/BELOW (altitude)," the manner in which the descent is executed to comply with the crossing altitude is at the pilot's discretion. This authorization to descend at pilot's discretion is only applicable to that portion of the flight to which the crossing altitude restriction applies, and the pilot is expected to comply with the crossing altitude as a provision of the clearance. Any other clearance in which pilot execution is optional will so state "AT PILOT'S DISCRETION."
 
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