Difference between DP and Takeoff Mims

[Dave S.]

I have several questions relating to a research project for a class I'm teaching in college. They are all directly or indirectly related to IFR departures. I will probably asks these if two or three different posts. My goal is to clarify as precisely as possible the distinction between several different aspects of IFR departures and I would like as much imput as possible. I am a CFII and 36 year ATC controller so I have some background. Thanks in advance.

Let's take Ontario Ca. as an example. Here goes...

ONTARIO, CA
ONTARIO INTL (ONT)
TAKEOFF MINIMUMS AND (OBSTACLE)
DEPARTURE PROCEDURES
AMDT 9 16147 (FAA)
TAKEOFF MINIMUMS: Rwy 8L, 8R, std. w/ min. climb of 285' per NM to 3000.
DEPARTURE PROCEDURE: Rwy 8L, 8R, climb heading 078° to 2600 then climbing right turn direct PDZ VORTAC, thence ... Rwys 26L, 26R, climb heading 258° to 2600 then climbing left turn direct PDZ VORTAC,
thence...
...climb in PDZ holding pattern (hold NE, right turns, 210° inbound) to cross PDZ VORTAC at or above MEA for route of flight before proceeding on course.

Under 91.175f (which only applies to 121,125, 129, 135 not 91) f2 states "...no pilot may takeoff from a civil airport under IFR unless the weather conditions at time of takeoff are at or above the weather minimums for IFR takeoff prescribed for that airport under part 97 of this chapter."

f2 states "...no pilot may takeoff from a civil airport under IFR unless the weather conditions at time of takeoff are at or above the weather minimums for IFR takeoff prescribed for that airport under part 97 of this chapter." and then goes on to give the "standard takeoff minimums" of 1 mile and 1/2 mile viz for 2 or less and more then 2 engine aircraft.

We all know that almost every airport has the Troubled T and has non-"standard" TO mims listed. As an aside this really makes the "standard" TO mims as really more of a "default" mim in case no non-standard(trouble t) is listed which is unusual. But I digress...

In the case of ONT above TO mims are listed. For example RY 8L and 8R require climb of 285 (not 200) fpm to 3000 ft before turning, to avoid obstacles.

Question #1. Are the Take off mims listed above those referred to in f2?

Question #2. If the answer to #1 is yes then is it true that the scenario could be stated like this..."If Ry 8L and 8R did not have these climb gradients and turning altitude listed, then a two engine aircraft would need 1 mile viz to depart."?

Question #3. If the answer to #2 is true, then, in this example, is it true that because a non-standard Takeoff mim IS listed, there is no default visibility requirement. In other words, a 135 operator could take off with zero visibility as long as he departs with a DER height of 35 feet, 285 climb gradient and not turn before 3000, correct or no?

Thanks,

tex

 

[midlifeflyer]

I have several questions relating to a research project for a class I'm teaching in college. They are all directly or indirectly related to IFR departures. I will probably asks these if two or three different posts. My goal is to clarify as precisely as possible the distinction between several different aspects of IFR departures and I would like as much imput as possible. I am a CFII and 36 year ATC controller so I have some background. Thanks in advance.

Let's take Ontario Ca. as an example. Here goes...

ONTARIO, CA
ONTARIO INTL (ONT)
TAKEOFF MINIMUMS AND (OBSTACLE)
DEPARTURE PROCEDURES
AMDT 9 16147 (FAA)
TAKEOFF MINIMUMS: Rwy 8L, 8R, std. w/ min. climb of 285' per NM to 3000.
DEPARTURE PROCEDURE: Rwy 8L, 8R, climb heading 078° to 2600 then climbing right turn direct PDZ VORTAC, thence ... Rwys 26L, 26R, climb heading 258° to 2600 then climbing left turn direct PDZ VORTAC,
thence...
...climb in PDZ holding pattern (hold NE, right turns, 210° inbound) to cross PDZ VORTAC at or above MEA for route of flight before proceeding on course.


In the case of ONT above TO mims are listed. For example RY 8L and 8R require climb of 285 (not 200) fpm to 3000 ft before turning, to avoid obstacles.

Question #1. Are the Take off mims listed above those referred to in f2?

Yes.

Question #2. If the answer to #1 is yes then is it true that the scenario could be stated like this..."If Ry 8L and 8R did not have these climb gradients and turning altitude listed, then a two engine aircraft would need 1 mile viz to depart."?

Yes.

Question #3. If the answer to #2 is true, then, in this example, is it true that because a non-standard Takeoff mim IS listed, there is no default visibility requirement. In other words, a 135 operator could take off with zero visibility as long as he departs with a DER height of 35 feet, 285 climb gradient and not turn before 3000, correct or no?

No. The only thing the alternate takeoff minimums change is the thing they change. Alternate takeoff minimums which contain both ceiling and visibility requirements changes both from the "default" to use your terms, but doesn't change the standard climb gradient (which guarantees obstacle clearance). Takeoff minimums which only contain a climb requirement only changes the standard climb requirement, not the visibility or ceiling requirement. Takeoff minimums which only contains a visibility.... etc. IOW, only the deviation from standard is being published.

@aterpster, did I manage to get that right?

 

[Dave S.]

Ok.

So there are the following parts to takeoff minimums....

Visibility...either 1 or 1/2 standard
Climb gradient...200fpm standard
DER height....35 ft standard
Turn altitude...400 ft standard
Ceiling....no ceiling is standard

Any of these might be given as a non-standard revision to the standards listed above. If one is not given then the standard applies.

Can anyone find an example of a different visibility being given as a non-standard revision of the 1 or 1/2 standard?

Usually they will include a higher ceiling in addition to the increased gradient. But I have never seen a higher biz given. Such as. “STD/w 250 fpm and 2 mile visibility”. I’ve never seen that.

Tex

 

[aterpster]

Usually they will include a higher ceiling in addition to the increased gradient. But I have never seen a higher biz given. Such as. “STD/w 250 fpm and 2 mile visibility”. I’ve never seen that.

Tex

Check KTVL Runway 18.

 

[Dave S.]

Ok thank you.

The takeoff minimum requires that you climb to 3000 before turning but the departure procedure says 2600. Why the difference?

Tex

 

[RussR]

Ok thank you.

The takeoff minimum requires that you climb to 3000 before turning but the departure procedure says 2600. Why the difference?

Tex

You are reading it incorrectly. The takeoff minimums require you to maintain the increased climb gradient of 285 ft per NM to 3000 MSL. This is not the altitude you turn at, this is the altitude you climb steeply to. The altitude you turn at is in the departure procedure section, which in this case is 2600 MSL.

So you need to maintain the steeper climb through part of the turn as well.

 

[IK04]

There are two parts to the Obstacle clearance DP. The first is the conditions: "[standard] w/ min. climb of 285' per NM to 3000." The second part is the Procedure, e.g. fly a heading, turn, intercept, hold, thence....

 

[Dave S.]

In other words fly 078 to 2600 thence... and do so at a rate of 285 per nm until at 3000 feet, at which time I could, if I wanted, ease off the 285 and climb at, say, 200?

If that is true are you saying that I can’t depart runway heading at 285 all the way to 3000 and be ensured of obstacle clearance?...that the only clear obstacle path lays along the 078 heading?

Tex

 

[Palmpilot]

...If that is true are you saying that I can’t depart runway heading at 285 all the way to 3000 and be ensured of obstacle clearance?...that the only clear obstacle path lays along the 078 heading?

Published departures are not necessarily the only way to stay clear of obstacles, but they ARE the only way that you are guaranteed obstacle clearance (provided that you meet or exceed the departure minimums and the specified climb gradient).

 

[IK04]

Remember, [min. climb of 285' per NM to 3000] is a performance requirement. It is not part of the flown procedure.

 

[Palmpilot]

Remember, [min. climb of 285' per NM to 3000] is a performance requirement. It is not part of the flown procedure.

What difference does that make?

 

[IK04]

What difference does that make?

If you can't climb to a notional 3,000 feet at 285 feet per Nautical Mile climb gradient, you CANNOT fly this DP.

 

[Dave S.]

Are you sure?

The 285 per nm was determined after a diverse departure assessment testing whether there were any intrusions by any obstacles into the 40:1 clearance plane was accomplished and, having found so, raised the path to 285 precisely to provide the required obstacle clearance per nautical mile. And that clearance is ensured along a 180 arc centered on the runway departure centerline.

That should, in and of itself, by definition, provide obstacle clearance. So why the 078 to 2600 thence...? What does that provide that the DD assessment increase to 285 to 3000 doesn’t give? What is the purpose of the dp in this case?

Tex

 

[IK04]

Again, the DP is broken into two parts. The standard minima plus climb performance for obstacle clearance and then the procedural track to get the departing aircraft up to the MEA for the enroute environment (in a hold).

The purpose of a DP is to get the departing aircraft into the enroute environment.

 

[RussR]

Are you sure?

The 285 per nm was determined after a diverse departure assessment testing whether there were any intrusions by any obstacles into the 40:1 clearance plane was accomplished and, having found so, raised the path to 285 precisely to provide the required obstacle clearance per nautical mile. And that clearance is ensured along a 180 arc centered on the runway departure centerline.

That should, in and of itself, by definition, provide obstacle clearance. So why the 078 to 2600 thence...? What does that provide that the DD assessment increase to 285 to 3000 doesn’t give? What is the purpose of the dp in this case?

Tex

No, the 285'/nm was not based on the diverse evaluation. It was based on an evaluation of the obstacles along the route of flight described in the "departure route". If you do not follow that route, you are in un-evaluated territory.

 

[Dave S.]

Then, please, can I have an answer to the previous question...


In this case is runway heading at 285 to 3000 guaranteed obstacle clearance or not?

If the dp was not there...same question?

Tex

 

[RussR]

No, not guaranteed. The only guarantee for obstacle clearance is if you follow the procedure - fly runway heading to 2600 then turn direct the VOR, while simultaneously climbing at a gradient of 285 ft per nm through 3000 ( at which point, yes, you can shallow your climb to 200 ft per nm if you wish).

If there was no Departure Route (but the takeoff minimums were still the same) then yes, you could climb in ANY direction as long as you maintained 285 ft per nm to 3000. But you could turn at 400 feet AGL as with a standard diverse departure.

 

[aterpster]

If there was no Departure Route (but the takeoff minimums were still the same) then yes, you could climb in ANY direction as long as you maintained 285 ft per nm to 3000. But you could turn at 400 feet AGL as with a standard diverse departure.

They're not supposed to make diverse departures with a climb gradient. If a climb gradient is required for diverse, a route departure often will negate the need for a climb gradient. KSVC used to have a diverse departure with some 350 feet per mile to clear terrain to the north, when to the south it is flat. That violated the least onerous climb gradient policy. NFPO QC manager had to hit the CSA FPT manager with a 2 by 4 to get him to comply with policy.

 

[RussR]

They're not supposed to make diverse departures with a climb gradient. If a climb gradient is required for diverse, a route departure often will negate the need for a climb gradient. KSVC used to have a diverse departure with some 350 feet per mile to clear terrain to the north, when to the south it is flat. That violated the least onerous climb gradient policy. NFPO QC manager had to hit the CSA FPT manager with a 2 by 4 to get him to comply with policy.

Usually true, but I was answering the question he asked.

However, 46F, Table 2-1-1, Situation 3, B, 2) allows this. And sometimes it happens - for instance an obstacle directly on centerline, 3.1 sm from DER just outside the ICA extended may be unavoidable with a route due to the turn radius involved. And since it's more than 3 sm away, a visibility mitigation option isn't permitted. So, a CG will be established, along with a VCOA.

 

[aterpster]

Usually true, but I was answering the question he asked.

However, 46F, Table 2-1-1, Situation 3, B, 2) allows this. And sometimes it happens - for instance an obstacle directly on centerline, 3.1 sm from DER just outside the ICA extended may be unavoidable with a route due to the turn radius involved. And since it's more than 3 sm away, a visibility mitigation option isn't permitted. So, a CG will be established, along with a VCOA.

It would unusual for that to affect more than one runway end, unlike the former situation at KSVC.

 

[Kritchlow]

I’m surprised on how many here are unfamiliar with a DP.

 

[aterpster]

I’m surprised on how many here are unfamiliar with a DP.

I'm not. There are DPs and ODPs.

 

[Palmpilot]

If you can't climb to a notional 3,000 feet at 285 feet per Nautical Mile climb gradient, you CANNOT fly this DP.

I was referring to your comment that the minimum climb gradient is not part of the procedure. I couldn't figure out what you meant by that. Or were you just pointing out that the minimums are in a different paragraph?

 

[aterpster]

With Jeppesen charts its on a chart associated with the STAR, IAP, airport diagram, and SID charts:

 

[Kritchlow]

I'm not. There are DPs and ODPs.

I know you’re not... My post was, well,.... sort of meant in a different way.

 

[luvflyin]

I'm not. There are DPs and ODPs.

ODP's are DP's. So are SID's.

 

[aterpster]

ODP's are DP's. So are SID's.

Nonetheless, there is a distinction, which is significant.

The ODP is not established unless the TERPs diverse departure area is not 40:1 clear And, in such circumstances, the ODP might not be 40:1 clear of obstacles. So, the ODP is for obstacle clearance, and the Part 91 pilot need not fly it (although he/she should) unless it is part of the ATC clearance (which is unusual).

OTOH, a SID is an ATC departure procedure, which is essentially a "canned" ATC clearance for IFR separation. A SID may or not be 40:1 clear of obstacles. But, if part of the clearance the SID must be flown as prescribed. (which would always be the case.)

 

[luvflyin]

Nonetheless, there is a distinction, which is significant.

The ODP is not established unless the TERPs diverse departure area is not 40:1 clear And, in such circumstances, the ODP might not be 40:1 clear of obstacles. So, the ODP is for obstacle clearance, and the Part 91 pilot need not fly it (although he/she should) unless it is part of the ATC clearance (which is unusual).

OTOH, a SID is an ATC departure procedure, which is essentially a "canned" ATC clearance for IFR separation. A SID may or not be 40:1 clear of obstacles. But, if part of the clearance the SID must be flown as prescribed. (which would always be the case.)

Yeah. Both ODP's and SID's need to deal with the 40:1 clearance thing. They both do it the same way by raising weather minimums to ensure pilots can see and avoid obstacles that penetrate it. Or require minimum angles of climb. It's really not that uncommon for ATC to 'assign' an ODP. If they do it, the pilot must fly it. Their flight path then becomes predictable and may be used for separation of aircraft, just like SID's. The differences between ODP's and SID's are really not all that different at the end of the day. IFR Departure Procedures, now known as ODP's, we're invented to separate airplanes from rocks. SID's were invented to reduce verbiage and separate aircraft. Even though SID's didn't originally have obstruction clearance criteria, they now do. So they both do the same thing, IF ATC 'assigns' the ODP. (I know you know this, just getting it out there in some other words.)

A SID may be published if needed for air
traffic control purposes. However, if an obstacle penetrates
what is called the 40:1 obstacle identification
surface, then the procedure designer chooses whether
to:
1. Establish a steeper than normal climb
gradient; or
2. Establish a steeper than normal climb
gradient with an alternative that increases takeoff
minima to allow the pilot to visually remain clear of
the obstacle(s); or
3. Design and publish a specific departure route;
or
4. A combination or all of the above.
______________

2. Where an obstacle departure procedure
(ODP) has been published for a location and pilot
compliance is necessary to ensure separation, include
the procedure as part of the ATC clearance.
EXAMPLE−
“Depart via the (airport name)(runway number) departure
procedure.”
Or
“Depart via the (graphic ODP name) obstacle departure
procedure.”
NOTE−
Some aircraft are required by 14 CFR 91.175 to depart a
runway under IFR using the ODP absent other instructions
from ATC

 

[midlifeflyer]

@aterpster and @luvflyin, I wonder whether the degree to which assignment of an ODP is common or not is based on factors such as location, whether the departure is from a towered or nontowered airport, whether it is a graphical ODP, whether tha ODP has a practical traffic management result, and others.

I've been assigned the HICKORY departure out of HKY. It's identified as an graphic ODP but looks and feels and is treated like a SID.

 

[luvflyin]

@aterpster and @luvflyin, I wonder whether the degree to which assignment of an ODP is common or not is based on factors such as location, whether the departure is from a towered or nontowered airport, whether it is a graphical ODP, whether tha ODP has a practical traffic management result, and others.

I've been assigned the HICKORY departure out of HKY. It's identified as an graphic ODP but looks and feels and is treated like a SID.

I think it may have become more common when the term DP was invented. It really wasn’t all that long ago. Before that there were Standard Instrument Departures, SID for short and IFR Deparure Procedures. IFR Departure Procedures got renamed Obstacle Departure Procedures, ODP for short. They both are under the ‘parent’ term Departure Procedure, DP for short. IFR Departure Procedures were always optional unless assigned by ATC just like they are now under their new name, ODP. I think that when DP became a ‘formal’ program they just naturally started assigning more of them.

The HICKORY THREE sure does look like like a good ol’ vector SID to me to. If it was a SID it would have to be evaluated for the same obstructions as ODP. I dunno what criteria there may or may not be to decide which kind of DP to name a Procedure. Maybe it was as simple the guy who built it figured “I had to miss the obstacles when I made this, so it must be one of them thar (OBSTACLE) ones.

 

[aterpster]

@aterpster and @luvflyin, I wonder whether the degree to which assignment of an ODP is common or not is based on factors such as location, whether the departure is from a towered or nontowered airport, whether it is a graphical ODP, whether tha ODP has a practical traffic management result, and others.

I've been assigned the HICKORY departure out of HKY. It's identified as an graphic ODP but looks and feels and is treated like a SID.

Check KEMT. The ODP doesn't even have top altitudes, because it is always assigned. Very busy airspace.

 

[luvflyin]

Check KEMT. The ODP doesn't even have top altitudes, because it is always assigned. Very busy airspace.

Yeah. That’s not a piece of sky where they are going to be letting you roll your own

 

[RussR]

Check KEMT. The ODP doesn't even have top altitudes, because it is always assigned. Very busy airspace.

Wally, I’m not sure what you mean here. ODPs don’t have top altitudes, only SIDS do. EMT only has a textual ODP and a DVA.

 

[aterpster]

Wally, I’m not sure what you mean here. ODPs don’t have top altitudes, only SIDS do. EMT only has a textual ODP and a DVA.

Poor choice of term. The KEMT ODP has no altitude to climb to other than to climb in a holding pattern at PDZ for MEA of route of flight.

 

[aterpster]

Wally, I’m not sure what you mean here. ODPs don’t have top altitudes, only SIDS do. EMT only has a textual ODP and a DVA.

To further remove the fog from my comments about the ODP at KEMT, note both missed approach procedures cross ADAMM at, or below, 2,500 to maintain 4,000. That crossing at ADAMM is to stay below the LAX Class B. I don't know why that restriction isn't in the ODP, but it's academic because SoCal always issues the ODP and always with the ADAMM restriction.