Why are ODPs not required in IMC?
- Thread starter Trogdor
- Start date
If it's a Bravo based airport, I do. Otherwise, no.
When flying out west I do check the ODPs because of the rocks. I've flown the one out of Logan Utah and the one out of Provo Utah.
MauleSkinner
Touchdown! Greaser!
The implication here being that you don’t check ODPs where they exist in flat country?
I'm certainly not as good at checking them.
MauleSkinner
Touchdown! Greaser!
I hear that fairly frequently with regard to airport analysis apps. “I use it when I’m in the mountains.” It’s usually pretty easy to come up with non-mountainous airports that they use where they should be using the apps to ensure legal takeoff planning.
My 2 most frequented airports have no ODP and no takeoff minimums. Only obstacle notes. Makes it hard to get in the habit. However, if I ever want to go pro, I need to do better at getting outside my narrow paradigm and looking beyond the ease of Part 91 flying.
luvflyin
Touchdown! Greaser!
Tokirbymd
Pre-takeoff checklist
- Joined
- Oct 17, 2019
- Messages
- 243
- Display Name
Display name:
Tokirbymd
That is exactly my point. FF departure takeoff mins goes to the beginning of the alphabet. If you are unfamiliar and looking for Western Carolina, you wouldn't find it. No reason why FF can't link at least to the page with the airport so you don't have to search forever.
- Joined
- Jul 3, 2012
- Messages
- 15,222
- Display Name
Display name:
Velocity173
Well I suppose FF could do a better job in linking the ODP but I really don’t think it’s too difficult to find any of the ODPs. No different then when we used paper. Flip a few pages til you get what you want. It’s not like you’re trying to find something at the last minute prior to take off. Go in the FBO, take a few minutes to plan the next leg and then go out an execute. Not that hard.
MauleSkinner
Touchdown! Greaser!
And do you know the impact, so to speak, of the obstacle notes? Do you need to worry about those?
luvflyin
Touchdown! Greaser!
4. Obstacles that are located within 1 NM of the DER and penetrate the 40:1 OCS are referred to as “low, close−in obstacles.” The standard required obstacle clearance (ROC) of 48 feet per NM to clear these obstacles would require a climb gradient greater than 200 feet per NM for a very short distance, only until the aircraft was 200 feet above the DER. To eliminate publishing an excessive climb gradient, the obstacle AGL/MSL height and location relative to the DER is noted in the “Take−off Minimums and (OBSTACLE) Departure Procedures” section of a given Terminal Procedures Publication (TPP) booklet.
(a) Pilots must refer to the TPP booklet or the Graphic ODP for information on these obstacles. These obstacle notes will no longer be published on SIDs. Pilots assigned a SID for departure must refer to the airport entry in the TPP to obtain information on these obstacles.
(b) The purpose of noting obstacles in the “Take−off Minimums and (OBSTACLE) Departure Procedures” section of the TPP is to identify the obstacle(s) and alert the pilot to the height and
location of the obstacle(s) so they can be avoided. This can be accomplished in a variety of ways; for example, the pilot may be able to see the obstruction and maneuver around the obstacle(s) if necessary; early liftoff/climb performance may allow the aircraft to cross well above the obstacle(s); or if the obstacle(s) cannot be visually acquired during departure, preflight planning should take into account what turns or other maneuvers may be necessary immediately after takeoff to avoid the obstruction(s).
MauleSkinner
Touchdown! Greaser!
Which means what, exactly, to a pilot?
luvflyin
Touchdown! Greaser!
1. Where am I
2. Where are the rocks/towers/trees/buildings etc.
3. What do I need to do to not hit them
MauleSkinner
Touchdown! Greaser!
How do you address this with #3? Do these need to be considered separately from the climb gradient assumed?
luvflyin
Touchdown! Greaser!
Yes. That's what it says. Pilots gotta apply the survival instinct below 200' above DER.
MauleSkinner
Touchdown! Greaser!
So how do you apply survival instinct to avoid obstacles that may be in the clouds?
luvflyin
Touchdown! Greaser!
Fly carefully. Fer instance, like not letting the wind be pushin ya around off the extended center line of the runway?
MauleSkinner
Touchdown! Greaser!
So you really don’t understand what these close-in obstacles are or why they’re published, do you?
aterpster
En-Route
- Joined
- Apr 15, 2011
- Messages
- 3,317
- Display Name
Display name:
aterpster
What are these two airports? If they have IAPs they eitherhave to have takeoff minimums or IFR takeoff "NA."
They have a takeoff minimums section but only obstacle notes. Feel free to tell me what I'm missing.
KPIA
3MY
Palmpilot
Touchdown! Greaser!
I don't even see any takeoff minimums in those "Takeoff Minimums" sections.
MauleSkinner
Touchdown! Greaser!
MauleSkinner
Touchdown! Greaser!
Jepp let me down!
luvflyin
Touchdown! Greaser!
I think I do. I know what the AIM says they are and why they're published. AIM 5-2-9 e. 4. But maybe the AIM is wrong. If so, then I'm wrong. Is there something the AIM, and therefore me are missing? I got my pen and paper out and am ready to take notes. Tell me all about it.
luvflyin
Touchdown! Greaser!
If it passes the Diverse Departure Assessment why would there need to be Takeoff Minimums? There are many airports that don't have them. May be they should change what they call the
“Take−off Minimums and (OBSTACLE) Departure Procedures” section of a given Terminal Procedures Publication (TPP) booklet. It does seem kind a silly to go there only to find there are no Take-off Minimums or a Departure Procedure. Only Take-off Obsatcle Notes or maybe a Diverse Vector Area.
MauleSkinner
Touchdown! Greaser!
They’re obstacles that, more often than not, don’t affect light GA airplanes.
Picking a specific example, Runway 14 at KSTP has obstacles beginning 190 feet from the DER, up to 129 feet, 1 foot right of centerline. Doing the math on that, it’s just over a 2700 ft/nm climb gradient, just slightly more than the 148 ft/mile normally allowed.
Staying on the extended centerline of the runway isn’t a good avoidance technique, and an early turn is going to point you toward other high terrain. You pretty much need to go over it.but since most of us don’t use all of the runway, the runway remaining can be used to flatten the required gradient. If I need, say, 2500 feet of distance to get to 50 feet, I extend my climb distance by almost 4000 feet (roughly 1300%), flattening the climb required to clear the obstacle to less than 200 ft/nm. So no additional climb or maneuvering is required.
They’re also only obstacles that penetrate the 40:1 surface, but are often less than a higher required gradient. Runway 36 at KTVL, for instance, requires a whopping 755 ft/nm climb gradient for the ODP. There are some significant close-in obstacles published, but meeting the 755 ft/mile exceeds what is needed to clear them.
So the bottom line is that yes, they need to be considered, but more often than not they aren’t a factor for pilots who have to do their own obstacle analysis.
My favorite is that they call out an object from my airport that is 15 feet AGL. If I hit that, I should never have had a license.They’re obstacles that, more often than not, don’t affect light GA airplanes.
Picking a specific example, Runway 14 at KSTP has obstacles beginning 190 feet from the DER, up to 129 feet, 1 foot right of centerline. Doing the math on that, it’s just over a 2700 ft/nm climb gradient, just slightly more than the 148 ft/mile normally allowed.
but since most of us don’t use all of the runway, the runway remaining can be used to flatten the required gradient. If I need, say, 2500 feet of distance to get to 50 feet, I extend my climb distance by almost 4000 feet (roughly 1300%), flattening the climb required to clear the obstacle to less than 200 ft/nm. So no additional climb or maneuvering is required.
They’re also only obstacles that penetrate the 40:1 surface, but are often less than a higher required gradient. Runway 36 at KTVL, for instance, requires a whopping 755 ft/nm climb gradient for the ODP. There are some significant close-in obstacles published, but meeting the 755 ft/mile exceeds what is needed to clear them.
So the bottom line is that yes, they need to be considered, but more often than not they aren’t a factor for pilots who have to do their own obstacle analysis.
luvflyin
Touchdown! Greaser!
Gotcha. I was a little snarky, thanks for replying. Just like the AIM says:They’re obstacles that, more often than not, don’t affect light GA airplanes.
Picking a specific example, Runway 14 at KSTP has obstacles beginning 190 feet from the DER, up to 129 feet, 1 foot right of centerline. Doing the math on that, it’s just over a 2700 ft/nm climb gradient, just slightly more than the 148 ft/mile normally allowed.
but since most of us don’t use all of the runway, the runway remaining can be used to flatten the required gradient. If I need, say, 2500 feet of distance to get to 50 feet, I extend my climb distance by almost 4000 feet (roughly 1300%), flattening the climb required to clear the obstacle to less than 200 ft/nm. So no additional climb or maneuvering is required.
They’re also only obstacles that penetrate the 40:1 surface, but are often less than a higher required gradient. Runway 36 at KTVL, for instance, requires a whopping 755 ft/nm climb gradient for the ODP. There are some significant close-in obstacles published, but meeting the 755 ft/mile exceeds what is needed to clear them.
So the bottom line is that yes, they need to be considered, but more often than not they aren’t a factor for pilots who have to do their own obstacle analysis.
"...and alert the pilot to the height and location of the obstacle(s) so they can be avoided. This can be accomplished in a variety of ways; for example, the pilot may be able to see the obstruction and maneuver around the obstacle(s) if necessary; early liftoff/climb performance may allow the aircraft to cross well above the obstacle(s); or if the obstacle(s) cannot be visually acquired during departure, preflight planning should take into account what turns or other maneuvers may be necessary immediately after takeoff to avoid the obstruction(s)."
I had said in my reply above to your "So how do you apply survival instinct to avoid obstacles that may be in the clouds?", I said "Fly carefully. Fer instance, like not letting the wind be pushin ya around off the extended center line of the runway?" But yeah, sometimes making sure to stay straight ahead for to long is not the answer. It was just a fer instance example. Like you said, KTVL's extreme Take-off Minimums climb angles were almost certainly because of obstructions beyond the 'close in' territory, within a mile of the runway and up to 200 agl. I do not think that TERP'ing those out, which they don't do, would have changed anything.
Last edited:
aterpster
En-Route
- Joined
- Apr 15, 2011
- Messages
- 3,317
- Display Name
Display name:
aterpster
Attachments
luvflyin
Touchdown! Greaser!
Getting to Takeoff Minimums in Foreflight just got easier. With the latest version, v14.0, it takes you to the entry for an Airport in the TPP directly to the page it is on instead of page one and making you scroll to the Airport you want. Slight glitch is it might take you to the second page of that entry instead of the first if it is one that spans two pages. No real biggie though, it does say (CON'T). You just swipe to get to the start.
N1120A
Pattern Altitude
I do if there is one. I get SIDs particularly out of several Class C and D airports. STARs less often, but also.
YTZ is a good example of that.
midlifeflyer
Touchdown! Greaser!
- Joined
- May 25, 2006
- Messages
- 17,189
- Display Name
Display name:
Fly
You just gotta love the Jepp zombies.
David Megginson
Pattern Altitude
In the NavCanada procedures, they're included with each airport's approach plates, typically as notes at the bottom of the airport diagram (see example below). When I first started flying to the U.S., I didn't even realise that I had to look somewhere else for them, but fortunately I was usually flying to airports with SIDs, so I didn't end up as an NTSB report.
PaulS
Touchdown! Greaser!
I love this new feature, flipping through 30 pages to get to an airport is a pia.
aterpster
En-Route
- Joined
- Apr 15, 2011
- Messages
- 3,317
- Display Name
Display name:
aterpster
NavCanada is more like Jeppesen than the FAA nummies at Silver Springs.
coma24
Line Up and Wait
Regarding how to clear the in-close obstacles, the original post did say:
The most important takeaway is that despite meeting the DER crossing restriction and published climb gradient, there are potential obstacles within 1nm of the field which can still bite you if you're unaware of their existence. I've not seen it become much of a factor, though, as the vast majority of aircraft are crossing the DER well above 35' AGL.
The most important takeaway is that despite meeting the DER crossing restriction and published climb gradient, there are potential obstacles within 1nm of the field which can still bite you if you're unaware of their existence. I've not seen it become much of a factor, though, as the vast majority of aircraft are crossing the DER well above 35' AGL.
That could be a bad idea on an IMC day even in flat country, which I believe is what you were suggesting, right?
Example:
IOWA CITY, IA - IOWA CITY MUNI (IOW)
TAKEOFF MINIMUMS AND (OBSTACLE)DEPARTURE PROCEDURES AMDT 4 19JUL18 (18200) (FAA)
DEPARTURE PROCEDURE: Rwy 7, climbing right turn heading 180° to intercept IOW VOR/DME R-057 to IOW VOR/DME before proceeding on course.
The reason is towers less than 10 miles from the airport:
This is also a good example of why I think ODPs should not be mandatory. With a little local knowledge, I know I can depart in IMC in any direction except to the east/northeast without any risk of running into, with a normal climb gradient. With a good climb gradient (think turboprop or jet) even a departure straight towards those towers is not an issue. Why should every IMC departure be inconvenienced by a detour?
- Martin
