Takeoff minimums, are you sure?

Discussion in 'Cleared for the Approach' started by Dave S., Jan 3, 2020.

  1. aterpster

    aterpster En-Route

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    TERPs doesn't cover OEI. Is the Caravan Part 25? If so, you need to have the OEI data specific to that runway. If Part 23, it's a "wing and a prayer."
     
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  2. MauleSkinner

    MauleSkinner Final Approach

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    Caravan’s a single engine...apparently @Clip4 is drinking again.
     
  3. aterpster

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    This looks like old criteria.
     
  4. Dave S.

    Dave S. Pre-takeoff checklist

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    I think we’re getting to the point that I’m having trouble with. If 900 represents the altitude where the increased cg ends, and the purpose of the increased cg is to clear an obstacle(s) then 900 represents the altitude. where the obstacle requiring a higher cg has been cleared and all remaining obstacles can be cleared with the standard 200 fpnm.

    If that’s the case then turning at 400 when 900 is prescribed puts you in danger of hitting the obstacle that the 900 is intended to protect. What am I missing here.

    Another way of putting is this...if, while climbing at the prescribed 238 I turn after reaching 400 presumably because I’m clear of any danger, then what is the need to continue climbing at the obstacle avoiding 238 highER than 400 up to 900?

    By the way, FSDO and Ops group both agree that the 900 represents the altitude that you can return to 200 AND the altitude where you can safely turnhaving cleared the controlling obstacles.
     
  5. Clip4

    Clip4 Final Approach

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    My point is a SEL during an engine loss cannot maintain the climb gradient. So the number is worthless in that context and 300-2 won’t assure obstacle avoidance either.
     
  6. MauleSkinner

    MauleSkinner Final Approach

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    300 & 2 doesn’t ensure obstacle avoidance in any way, shape or form. Pilots have been crashing into stuff in visual conditions for longer than anybody on this board has been alive.
     
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  7. MauleSkinner

    MauleSkinner Final Approach

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    Ask them for a reference.
     
  8. dmspilot

    dmspilot En-Route

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    What if the obstacle is aligned with the runway? Then not turning "puts you in danger". :eek:
     
  9. MauleSkinner

    MauleSkinner Final Approach

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    Take a look at what’s in the vicinity of the airport and tell us which is the one obstacle that the ODP is protecting you from. You’ll find numerous obstacles for both of the runways you mentioned, but you’ll find that turns at 400 feet (except for the right turn off of 50F) will clear obstacles if the published gradient is made good to the published altitude, with 200 ft/mile thereafter.
     
  10. Dave S.

    Dave S. Pre-takeoff checklist

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    A pilot is free to rationalize any decision regarding what or how he will pay attention to climb out obstacle clearances. If you want to turn at 400 then fine. You can also read the info and decide to turn at 300 on a heading you think will be safe. The pilot decides. But the 900 (in this case) is intended to represent a clear altitude for a diverse heading after reaching 900. That is the purpose of the altitude. One is free do do your own calculations if yould like and turn when you want. A pilot can do whatever his career can stand.

    A DP is another matter especially if you’re 121, 135, or have accepted a DP clearance.

    So after all of this here is what Ops Group, FSDO and I think some of us agree on.

    1). The “to xxxx” altitude represents a obstacle free diverse departure altitude provided you climb at the prescribed cg and thereafter 200 cg.

    2) a diverse turn prior to the “to xxxx” altitude is not assured to clear obstacles by the prescribed ROC by the FAA. You live or die by you own calculations.

    3). The standard or non-standard minimums are pre-airborne go/no go requirements

    4). The 400 foot altitude associated with standard minimums and standard cg is the altitude the pilot is assumed to climb to before turning on course and be clear of obstacles. If the diverse departure assessment has determined that a standard diverse departure is allowable and ROC assured by the FAA then it does so assuming the pilot wont turn prior to 400 feet.

    Regarding 400 feet or 900 or any “to xxxx” altitude, for that matter...if you could magically take an elevator to that altitude and begin the flight there, you know that any turn in any direction will be cleared of all obstacles with appropriate ROC if you maintain 200 fpnm from that point on.

    So getting UP TO that altitude is the main issue.
    And that is assured obstacle free provided you use the prescribed cg. And a DP makes the the navigation less onerous.

    Thanks everyone for the input.

    Tex
     
  11. dmspilot

    dmspilot En-Route

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    You have drawn a conclusion and are "rationalizing" excuses to make the conclusion seem true. You have no evidence to support #2 .

    There are two ways to avoid an obstacle: vertically or laterally. Outside of the Initial Climb Area (ICA), meaning above 400 feet, obstacles are assessed in all directions. If an obstacle pierces of 40:1 obstacle clearance surface, the solution is 1) publish a route to avoid the obstacle laterally, or 2) publish a minimum climb gradient with standard takeoff minimums to avoid the obstacle vertically (and include an option of higher takeoff minimums with standard climb gradient that will allow visual avoidance of the obstacle), or a combination of options 1) and 2). If you must combine the required climb gradient with a particular route, the procedure will explicitly specify so. Source: Order 8260.46G Table 2-1-1

    For example, KGNT:
    TAKEOFF MINIMUMS: Rwy 13, 2400-2 or std. with a min. climb of 420' per NM to 11000.
    DEPARTURE PROCEDURE: Rwy 13, climb runway heading to join V12 at or above 11000 before proceeding on course.


    Notice both a heading and a climb gradient are specified. If only one is specified, you only need one.
     
  12. Dave S.

    Dave S. Pre-takeoff checklist

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    I’m sure it is me. I am not asking the right question or wording it correctly or something but I still am missing something. I’ll just have to try to figure out a way to describe it correctly to the students.

    Thanks
     
  13. Palmpilot

    Palmpilot Touchdown! Greaser! PoA Supporter

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    That's especially true when the name of the airport is misspelled in the opening post.
     
  14. denverpilot

    denverpilot Tied Down PoA Supporter

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    How about this?

    Imagine an airport in a perfect circular valley. The climb gradient will protect you from hitting the ridge line surrounding you in all directions.

    However, you can still turn and circle all you like for the climb inside the valley and never hit anything ever. Start the turn at 400, or the top of the climb gradient, it makes no difference.

    As long as you don’t aim at the ridge line.

    Purely hypothetical of course, but it teaches that the climb gradient isn’t protecting the turn altitude at all. It’s protecting from a perfectly circular obstacle perhaps, all the way around the airport.

    Now make the perfect circle infinitely high wall except in one 20 degree arc. It’s still the original height. Now the climb gradient will include a heading toward that notch.

    You can still turn whenever you want to, but you’ll have to fly the heading and climb gradient to go over the low spot.

    Or... they’ll alternatively publish a full departure procedure to take you through the notch.

    The turn without a heading is meaningless other than there’s something in some direction that needs to be outclimbed. The only way to know for sure what it is, is a VFR chart. It’s inside the normal gradient plane is ALL you really know from the climb requirement.

    If there’s a published departure procedure and you’re on it, you then know specific altitudes for MEA, etc.

    You also have the published MSA circle on any approach plates for that airport which will give a major hint at which direction the obstacle(s) is/are.

    Without a heading published, when to turn isn’t determined by the departure gradient required. You determine that from other information and planning. You just have a nice piece of info that if you can maintain the gradient you will miss whatever it is. You don’t know where it is at ALL from a generic climb gradient requirement.

    Is that hypothetical helpful at all?
     
  15. PPC1052

    PPC1052 En-Route

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    That there could be other restrictions on turning provided either in the ODP and/or your clearance if such a turn really did put you in jeopardy.
     
  16. PPC1052

    PPC1052 En-Route

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    That makes no sense. Of course it has value. If you calculate that you can't maintain that climb during an engine loss, then you can decide that that take off IFR isn't a good choice, or at least make plans as to what you might do if you choose to risk it. It's certainly better than not knowing that when you lose an engine if you keep going you're hitting the rocks absent an alternate plan.
     
  17. PPC1052

    PPC1052 En-Route

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    That would certainly be a rational convention for the FAA to implement in designing departures and writing alternate takeoff minimums. The problem is, that is not what the FAA has done. Can you point to a single written document issued by the FAA in support of your interpretation? Is there anything that has ever been issued which tells pilots that when an alternate climb gradient if given that they cannot turn at 400 feet? If I'm wrong, show me. It could save my life one day.
     
  18. midlifeflyer

    midlifeflyer Touchdown! Greaser!

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    FIFY

    Here's the thing. If a straight ahead climb to the climb gradient altitude is implicit, there are irrelevant ODPs. Some are even contradictory. Here's one airport with examples of both.

    Runway 23 - why have an ODP which says to climb 230 to 2800 if the Takeoff Minimums climb gradient already says that? Redundant.

    Runway 29 - Why have an ODP says to climb on a certain heading until 1200 if you have to wait until 2400 or 4600? Contradictory!

    upload_2020-1-4_8-27-9.png
     
    Last edited: Jan 4, 2020
  19. Velocity173

    Velocity173 Touchdown! Greaser! PoA Supporter

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    In all seriousness, I think your college should have someone who’s taught TERPS give a lecture on the subject. Doesn’t need to be an entire course, just a lab or something. Dry stuff but they’ll get a lot out of it.
     
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  20. MauleSkinner

    MauleSkinner Final Approach

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    Well, when this stuff starts showing up in pilots, at least we’ll know where it came from. :rolleyes:
     
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  21. aterpster

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    My excuse is it was early in the morning. :)
     
  22. Kenny Phillips

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    Ha, I read your presentation, and was pleasantly surprised to see Red Oak Muni! I've been to Red Oak many times, as my GF is from there, and I hope to fly there (for the first time) in the next few months.
     
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  23. dtuuri

    dtuuri En-Route

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    It's mentioned in another tutorial too. I don't recall which one off hand.

    This thread is as amusing as watching six cats chase Dave S' tail. Nobody able to catch it with just the right combination of words. :popcorn:
     
  24. aterpster

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    Here is Jeppesen's presentation, which is easier to read and parse:

    KVSF takeoff.jpg
     
  25. midlifeflyer

    midlifeflyer Touchdown! Greaser!

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    I know people say that but having used both, I really never saw much difference except when I was using paper - the Jepp paper was definitely better quality. I guess it's what one is used to.

    But either way, it makes the point. The "rate of climb" deals with, the non-standard...umm...rate of climb. The ODP deals with course and direction.

    Using Dave's theory, there is a direct conflict between the information in red and the information in blue. According to the ODP, you can turn at 1200 AGL. According to Dave you can't turn until 3400 or 4600 depending on your rate of climb.

    Clipboard02.png
     
  26. aterpster

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    Dave's wrong. Let me disregard the VCOA and assume flying for hire. For Runway 29 if I can only make good 490'/nm I have to do it to at least 4,600 and am bound by wx of not less than 800 and 2 1/2, and I should turn on course at 1,200. However, if I can make good 630'/nm t0 3,400 I can use standard takeoff minimums, and I still should turn on course leaving 1,200. The departure becomes a diverse departure at 1,200 provided I continue to make good the applicable climb gradient to the altitude associated with climb gradient. Finally, the turn on course could be straight ahead if my cleared route is straight-ahead.

    EDIT: Because the departure is diverse leaving 1,200, Dave could elect to fly straight-ahead to 4,600 before turning, absent any ATC instruction to the contrary.
     
    Last edited: Jan 4, 2020
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  27. Clip4

    Clip4 Final Approach

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    Take off minimums are a regulation. The take off alternate minimums published for an airport apply to all the operations covered by the regulation. There are a lot of single engine operations. You cannot plan of obstacle clearance OEI in a SE airplane. If there is a forest at the end of the runway as an obstacle, you aren’t going to missing it visually.
     
  28. midlifeflyer

    midlifeflyer Touchdown! Greaser!

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    We've all pretty much said the same thing in a number of different ways.
     
  29. dtuuri

    dtuuri En-Route

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    Maybe an earlier version of TERPS said it better (See the opening paragraphs of Chapter 12): http://www.mikeg.net/library/files/terps.pdf

    The term "diverse" describes an area around the departure runway, i.e., a "zone", in which obstacles are assessed. The study may indicate the need for specific "departure routes", which we call ODPs or weather minimums to avoid obstructions visually. I cringe at your use of the term "diverse turn" and think it reveals a misunderstanding on your part. You seem, to me, to be connecting what the pilot does to the use of the term rather than what the procedure specialist does. With that, I bid adieu.
     
  30. Clip4

    Clip4 Final Approach

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    Agree
     
  31. Dave S.

    Dave S. Pre-takeoff checklist

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    I did and they didn’t give what I considered a satisfactory answer. I asked “what does 400 to 1100 mean?” Then I asked “then what? What happens at 1100?” Just like I asked here.

    I asked it we can return to 200? The answer was yes. I asked if it was then safe to run on course...any course and bothe said yes.

    I’ll ask it here again. What does the FAA say the pilot can do at the “to xxxx” altitude? That we can’t do until the “to xxxx” altitude?

    Assuming no DP...

    The FSDO and ops group answer is....
    1) you can’t turn on course (safely clear of objects) until then, and
    2) the increased cg of 400 fpnm is over and the pilot can return to the default cg of 200

    That’s the FAA answer. And some of the answers here seem to be in conflict with that.
     
  32. dmspilot

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    Your narrative of the conversation (first quote) and your paraphrasing of their answer (second quote) are not the same thing. Being able to turn at 1,100' not the same thing as not being able to turn below 1,100'. What did they actually say? You either asked the wrong question or misinterpreted their answer, or both. Would not be surprising considering your post history. Or, they are simply wrong. Would also not be surprising since FSDOs give wrong answers to questions on a regular basis.
     
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  33. aterpster

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    Except we are not required to turn higher than 1,200, but we must make good the applicable climb gradient to either 3,400 or 4,600.
     
  34. Dave S.

    Dave S. Pre-takeoff checklist

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    I have described it several times as being able to turn safely clear of the obstacles that the increased cg and the “to xxxx” altitude is intended to protect you from. I have also stated that of course a pilot is free to rationalize or calculate a turn sooner based on obstacle data. Please stop treating me like I’m new at this.

    I’m have been asking for any clarification and people want to argue. Where exactly are we at odds here?

    The “to xxxx” altitude is the, let’s call it, the safe turn altitude and the increased cg is to get you to that altitude safely, and yes, you can turn early if you want but you are on your own on your calculations.

    My main clarification involved the original DP example where the DP callers for a right turn at 1400. So, if you read some of my questions, what happens between 1300 and 1400? Which cg do you use since, presumably you’re still runway heading during that time. If you cleared the controlling obstacle based on runway heading at 1300 why can’t you climb at 200 to 1400 still on runway heading since 1400 is to protect you from some controlling obstacle
    To the right.

    I appreciate yall’s help and please forgive any of my frustration.
     
  35. dmspilot

    dmspilot En-Route

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    You have not attempted to refute any of the arguments that poke holes in your theory.

    I see. We are supposed to assume you are correct, before we can discuss the topic.
     
  36. MauleSkinner

    MauleSkinner Final Approach

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    Given the lack of obstacle data pilots have, that statement is going to kill people.

    This is where you’re going off the rails...if there was a heading or track requirement beyond 400 feet, that heading or track would be published in the DP. That’s not rationalizing...that’s flying the way the procedures are designed and presented.

    Your “main clarification” is also predicated on your faulty assumption. Above 400 AGL, the pilot can turn left or go straight, but any right turns have to wait until at least 1400 MSL.
     
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  37. Dave S.

    Dave S. Pre-takeoff checklist

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    I haven’t refuted yet because I’m having trouble it seems to get a simple straight answer to a few questions. I’ll try again.

    If I can turn safely at 400 as you state then what is “ clinb to 512 to 1100” for? If I can turn at 400 why do I care anymore about climbing at a higher cg. I know why I do it but I wouldn’t be able to explain the logic to a student. He asks “if I’m safe at 400 then why 1100?”

    What do I tell him?
     
  38. MauleSkinner

    MauleSkinner Final Approach

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    Because there is more than one obstacle in the vicinity of the airport for which the gradient is required. You’re not “safe” as the term is used in the question.
     
    Last edited: Jan 4, 2020
  39. DogoPilot

    DogoPilot Filing Flight Plan

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    What I gather from the responses and from reading the procedure in the first post is that you're safe to start a turn to the left at 400' but you have to continue to climb at the higher climb gradient up to 1300' (not sure where the 1100' is coming from). Turning and climbing at the higher gradient aren't mutually exclusive.

    I think the example given by denverpilot makes it clear why this could be the case.
     
    Last edited: Jan 4, 2020
  40. midlifeflyer

    midlifeflyer Touchdown! Greaser!

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    A FSDO answer is not the FAA's answer.