Departure IFR to Enroute Structure

Sidious

Sidious

Well-Known Member
I was always taught as a student to plan an IFR country as if you have no radios, that way in the event you lose them, then you have already planned to an IAF and have your bases covered.

That being said...

On departure, is it reasonable to say (teach) that as long as an ODP has not been issued for your departure airport, that a 200 FPNM climb will insure obstacle clearance to the enroute structure?

Along with that line of thought, if your departure airport has no IAP and thus no DP even available then can the same assumption of 200 FPNM still be made?

I think not... but then how do you explain to your students what to do at an uncontrolled airport to get on the enroute structure.

These scenarios all revolve around a non-GPS airplane.

Thanks!
 
There are SIDS and ODP's.

The SID has the required climb gradients listed. The ODP, or at least all that I have seen have the standard terps requirement.

I have to check the AIM again but I am pretty sure if you are operating IFR and are climbing out of an airport you have to make the terps MIN requirement for climb to ensure obstacle clearance...

Then again i've had my head in part 25 aircraft for the better part of the year.
 
Sidious said:
On departure, is it reasonable to say (teach) that as long as an ODP has not been issued for your departure airport, that a 200 FPNM climb will insure obstacle clearance to the enroute structure?
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Not quite. The climb gradient alone is insufficient:

  1. Cross the departure end of the runway at least 35 feet above the DER elevation,
  2. climb to at least 400 feet above airport elevation before making any turns, and finally,
  3. ensure the aircraft is achieving a climb gradient of at least 200 fpm.
with that line of thought, if your departure airport has no IAP and thus no DP even available then can the same assumption of 200 FPNM still be made?
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Nope, you can make no assumptions at all.

but then how do you explain to your students what to do at an uncontrolled airport to get on the enroute structure.
Click to expand...
Several options:

  1. Don't do it, or
  2. Do it only if you can maintain visual obstacle clearance until reaching minimum IFR altitudes, or
  3. Use a sectional to plot a departure course.
(Note this isn't related to uncontrolled vs controlled field.)
 
tgrayson said:
Not quite. The climb gradient alone is insufficient:
Click to expand...

I recall, but can't source it, your 35' over the threshold and 200 or 250 ft/NM as being the standard for airports not having an ODP. I was taught it and shown the source, but too lazy to go looking for it now since I am not going for a II anytime soon. :)
 
tgrayson said:
Not quite. The climb gradient alone is insufficient:

  1. Cross the departure end of the runway at least 35 feet above the DER elevation,
  2. climb to at least 400 feet above airport elevation before making any turns, and finally,
  3. ensure the aircraft is achieving a climb gradient of at least 200 fpm.
Nope, you can make no assumptions at all.

Several options:

  1. Don't do it, or
  2. Do it only if you can maintain visual obstacle clearance until reaching minimum IFR altitudes, or
  3. Use a sectional to plot a departure course.
(Note this isn't related to uncontrolled vs controlled field.)
Click to expand...

Under part 91 the t/o mins are 0/0 in addition if there are no SID's or DP's available and in the case of an uncontrolled field wouldn’t the the present controlling agency (Center) determine those mins??
 
IIRC, if you don't have an IAP (in other words no Jepp plate) for an airport then that airport has not been surveyed for obstacles thus the 200'/NM doesn't work.

If you do have an IAP and no published SID or textual ODP then the 200'/NM does work and that gives you terrain clearance up to MEA or MCA at a fix for your route of flight. Don't fall into the trap of thinking it will get you to the MSA.

As Mr. Grayson has pointed out, the 200'/NM (3.3% gradient) is only part of the picture, you have to meet the other criteria as well.

As far as how to do it at airports with no IAP;

Use a sectional chart and use a nearby VOR to make an "airway" from your departure airport to the VOR then you can join the enroute structure (if there are airways off that VOR). Simply draw your course, measure 4NM either side of it, check for obstacles that are within that 8NM wide corridor and make your "MEA" 1000 feet above the highest one. You can figure out how far it will take you to climb to that altitude from your aircrafts performance charts, for simplicity plan a runway heading climb out and make sure there are no obstacles from the end of the runway to that MEA within the distance you figure it will take to climb.

Also consider the ground track from the top of climb to get on course with your made up airway and don't forget to consider winds.

Is this a practical way? Not really, I would, in reality, depart VFR and reach an MEA or MSA before going IFR/IMC. But it is a good way to practice with a student determining altitudes, climb requirements, etc.
 
tgrayson said:
Several options:

  1. Don't do it, or
  2. Do it only if you can maintain visual obstacle clearance until reaching minimum IFR altitudes, or
  3. Use a sectional to plot a departure course.
(Note this isn't related to uncontrolled vs controlled field.)
Click to expand...



Ok, this was in line with what I was planning. The reason I mentioned uncontrolled is so that Radar Vectors would not be an option right after takeoff.

Thanks everyone else for their input as well. Very much appreciated
 
Sidious said:
The reason I mentioned uncontrolled is so that Radar Vectors would not be an option right after takeoff.
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About the only time that you can count on radar vectors to keep you out of terrain on departure are Class B and Class C TRACONs.
 
shdw said:
I recall, but can't source it, your 35' over the threshold and 200 or 250 ft/NM as being the standard for airports not having an ODP. I was taught it and shown the source, but too lazy to go looking for it now since I am not going for a II anytime soon. :)
Click to expand...

TERPS Obstacle Identification Surface starts at 35' DER crossing for Civil and Army fields, but at 0' DER crossing for USAF/USN fields, unless a specific crossing height is noted.
 
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