It’s been 30 years since a USAF C-130 ran into an 11,000-foot ridge in the Gros Ventre Wilderness Area about 12 nm east of Jackson Hole, Wyoming, because the crew trusted four big Allison turboprops to outclimb the precipitous terrain around KJAC rather than using approved procedures to avoid running into cumulo-granite while climbing. You can find a detailed analysis of that accident on Flight Safety’s website.
In this article, I’m going to talk about what you should do (and what they should have done) about obstruction clearance when departing IFR.
The Regs
Let’s start with the regulation governing IFR departures: 14 CFR 91.175(f). It begins with the following: “Civil airport takeoff minimums. This paragraph applies to persons operating an aircraft under part 121, 125, 129, or 135 of this chapter.”
That means if you’re operating under Part 91, you can legally ignore the rest of this article. Of course, that will put you at serious risk of following HAVOC 58 into the side of a hill, which is why it’s wise to follow these procedures even if you aren’t legally required to do so. Where there are no published procedures, commercial operators are not permitted to depart IFR. Part 91 operators are permitted to make their own decisions and even create their own procedures at their own risk using sectional charts, GPSs, and whatever else they believe will allow a safe pathway from the runway to the MEA, even where ODPs are published.
The first requirement is, unless otherwise published, a minimum visibility of 1 mile for airplanes with one or two engines, or ½ mile for more than two, for any airport with published instrument procedures. One consideration beyond that is the possibility of a fire truck, the airport owner’s van, or a cow on the runway. My personal absolute minimum visibility is thus my accelerate-stop distance (about 1,000 feet in a light single at sea level) so I can stop before I run into an unexpected obstacle suddenly looming before me out of the fog.
It is interesting to note that absent a specified minimum for takeoff in the published departure information for your departure airport, there is no minimum ceiling, which means you can legally take off with ceiling indefinite zero/sky obscured. That said, a takeoff can take a heart-pounding, blood pressure-popping turn if the outside view ahead disappears as you rotate.
The process of determining safe procedures for IFR departures from an airport begins with a survey of the terrain and obstructions around that airport and the FAA’s basic IFR departure standards described in AIM 5-2-9:
- Cross the departure end of the runway (DER) at least 35 feet above it.
- Climb straight ahead ±15° at a minimum gradient of 200ft/nm to 400 above the DER.
- Turn on course maintaining 200 ft/nm to the MEA.
If adherence to this procedure will achieve required terrain/obstruction clearance, no further direction is provided and it’s up to you to fly that profile. It’s always your responsibility (on either the default procedure just described or a specific published procedure for that airport) to check that the climb rate and groundspeed you intend to fly will achieve the required climb gradient. This requires GS, not just indicated airspeed (IAS), so you must convert the climb IAS you plan to true airspeed (TAS) and then figure the effect of wind to get GS. The FAA provides two tables on the last two pages of the Digital Terminal Procedures Supplement to help you do this.
When It Doesn’t Fly
When this standard climbout procedure won’t work, the FAA establishes either higher weather requirements to allow visual obstruction avoidance, greater climb gradient, or a specific flight path to achieve the necessary terrain/obstruction clearance, or a combination of them. These are normally published in the Takeoff Mins section of the FAA AeroNav Terminal Procedures or on the Airport Diagram page of the Jeppesen Airway Manual. AeroNav also highlights this by putting a “triangle-T” symbol on each Standard Instrument Approach Procedure chart for the affected airport.
Cumberland, Maryland (KCBE), located between a couple of ridgelines, provides excellent examples. First, it establishes higher takeoff minimum weather and climb gradients:
TAKEOFF MINIMUMS:
Rwys 11, 29, NA – Obstacles.
Rwy 5, 700-3 w/min climb of 308’/NM to 3100 or std w/min climb of 350’/NM to 2700, or 2800-3 for VCOA.
Rwy 23, 1200-3 w/min climb of 444’/NM to 2900 or std w/min climb of 857’/NM to 2400, or 2800-3 for VCOA.
The first thing we see is that IFR departures are not approved on Rwy 11/29, which is both short and perpendicular to the ridgelines. You just can’t stay far enough from the ridges using standard rate turns if you launch on that runway. Next, we see several options depending on what climb gradient you can maintain—more climb gradient allows lower weather. At some airports you may also see something like “min climb of 250’/NM or std w/takeoff at least 400 ft before DER”. In this case taking off sooner gets you high enough over the DER that a standard 200’/NM will clear the controlling obstacle but if you’re only 35 AGL at the DER you’ll need a steeper climbout.
VCOA: Rwys 5, 23, obtain ATC approval for VCOA when requesting IFR clearance. Climb in visual conditions to cross Greater Cumberland Rgnl airport at or above 3,400 feet before proceeding on course.
Visual Climb Over Airport
The last item is the “VCOA,” or “visual climb over airport,” used when you cannot make the lowest minimum climb gradient in the Takeoff Mins. For the VCOA, you circle up over the airport in visual flight conditions high enough that you can then push out from there and clear the obstacles with only the standard 200’/NM climb gradient from the top of the VCOA. If you do the math with airport elevation and the minimum ceiling, you’ll see that the minimum ceiling will be 200 feet above the top altitude and the minimum visibility will be 3 sm. In this case, the airport elevation is 758 feet, and the minimum ceiling is 2,800 feet, putting the cloud bases at 3,558 feet, a bit less than 200 feet above the VCOA top altitude of 3,400 feet. Also, since this is done on an IFR clearance, and separation from any IFR traffic in the area is provided, it’s OK to be less than the normal VFR 500 feet below the clouds.
DEPARTURE PROCEDURE:
Rwy 5, climb on heading 049° to 2500 before proceeding on course.
Rwy 23, climb on heading 229° to 3900 before proceeding on course.
In addition to the Takeoff Mins, the procedures provide protection during the climb to the MEA. When there are obstructions preventing a turn on course until reaching a higher altitude than the standard 400 above the DER, a path to fly to avoid those obstacles will also be provided. At CBE, runways 5 and 23 are run parallel to the ridgelines, so you must climb out in the valley above the terrain next to you before turning on course. And do be aware that in these procedures all altitudes are given MSL while all ceilings are given AGL as they are reported by weather systems.
In addition to the textual ODPs discussed above, in some cases a graphical ODP is used to provide a picture of the flight path. Since we’re talking about Jackson Hole, let’s discuss the one which HAVOC 58 should have used. Like the textual ODPs, the graphical ODPs give you any applicable takeoff minimum weather or climb gradients, in this case:
TAKEOFF MINIMUMS:
Rwy 19: Standard with a minimum climb of 335′ per NM to 14000 or 4400-3 for climb in visual conditions.
Rwy 1: Not authorized – ATC
While it looks a bit like a SID, it has no purpose but obstacle clearance, as opposed to SIDs which are developed to avoid having to read a long and complicated departure clearance, often including lost communication procedures. Note also that the TETON THREE is only authorized for Runway 19, since the turn radius of a 180-degree turn off Runway 1 would run you into the ridge. Conversely, for departures on Runway 1, there is the GEYSER SIX, which is only authorized for departing on Runway 1. If you want to take off south and go north, you’re going to have to fly the TETON THREE all the way to Idaho Falls before turning north.
When departing IFR where an ODP is published, other than a VCOA, you do not need special coordination with ATC. Per the AIM, “ODPs are recommended for obstruction clearance and may be flown without ATC clearance unless an alternate departure procedure (SID or radar vector) has been specifically assigned by ATC.”
There’s More …
We’ve talked about the procedures for ensuring obstacle clearance during IFR departures, which is only half the issue, the other half being an understanding of the Standard Instrument Departures used by ATC to give complicated departure instructions in just a few words. We’ll get to those next time in a separate report here at Instrument Aviator on Avbrief.
Hey Ron, I believe the correct symbology on the Government charts for ODPs or Non-standard T/o minima is the inverted triangle “T”.
It is indeed. DOH!
Hey, it happens.
Realize not main topic of post, but Part 91 0-0 departure falls under the “just because you can doesn’t me you should” and you’ve probably heard the cliche “military only entrusts special card (0-0 authorized) with those smart enough not to use it”. I fail to understand the mission driver in Part 91 (is there really a life and death urgency absent troops in contact or someone bleeding out?)
My question to those suggesting it is what happens when you have an immediate return emergency or your glass cockpit takes a dump because a ground fails)…usually met with blank stare, my suggestion is circling mins.
“…doesn’t mean you should…”
…still getting used to the opposable thumbs.
Excellent points. Of course, there are many places where an “immediate return” can be to another nearby airport with better conditions. Imagine you take off from Garrett County (2G4) in Western Maryland, located on top of the hill at nearly 3000 MSL, often socked in while Morgantown WV (MGW) about 15 miles away and 1700 feet lower has VFR weather. You can land at MGW about as fast as you could fly an approach back to 3G4. So sometimes taking off in unreturnable weather isn’t too bad if you have a good nearby takeoff alternate.
Key point you make is having a plan for that, not just hope!
For single engine recip/light twin I’d rather have conditions to stay VMC for return on initial climb away when connecting rod(s) may depart the crankcase.
Turbine multi-crew is a different animal where I’d be fine going IMC knowing we’d likely make it those 15 miles.
Pt 135 requires pilots to designate a takeoff alternate within 1hr flight time if departing below landing minimums to cover an emergency return scenario. The FAA only allows below landing minimums with at least a 2 pilot crew. No single pilot below landing mins departures. Pt 91 has no such requirement. Be careful with 0/0 departures in Canada. Transport Canada makes no distinction between private and commercial flights as far as IFR minimums are concerned. A pilot at a company I flew for did 0/0 departure out of a Canadian airport on a pt91 positioning flight and the next morning the chief pilot got a phone call from TC expressing their displeasure about that departure.
Great article, Ron, thank you! I believe you meant to say the FAA AeroNav charts show a “triangle-T” to denote takeoff and departure procedures, the “A” denotes non-standard alternate minimums.
I had just taken my instrument rating checkride about 3 weeks before that tragic C130 crash at Jackson Hole. Jackson is about an hour’s flight from my home base of Lander, WY, so that crash was more or less right in the neighborhood. I recall finding it hard to imagine how a C130 crew could miss such an important component of mountain/IFR/night flying procedures. RIP.
Good stuff…my Monday morning IFR refresher, thanks
Thanks. Good to know. As a small aircraft pilot following part 91; I avoid IFR arrivals and departures. Though, I have stayed prepped in case I need to perform and IFR departure or arrival. But, I will land at a VFR airport before flying into IFR conditions unless I know the arrival airport, or the airport next to the arrival airport is VFR. I flew home from Eureka, CA, some 37 years ago to Reno, NV, on weekends, I flew VFR over the top in a C-172 knowing no clouds were on the eastern side of the Sierras Mts.; with several alternate airports available. Would I do this now? Probably not. Even though it appeared safe at the time.
“Though, I have stayed prepped in case I need to perform and IFR departure or arrival.”
I can’t imagine ever having to make an IFR departure since leaving the military and airline. The first time I said to myself, “I think I can do this” was the first time I said to myself, “Not today”.
I have made one IFR departure that I remember; leaving Eureka, CA, on a Friday night, going to Reno, NV; I hired a flight instructor to climb out of the
overcast and I dropped him off at Kneeland in the hills east of Eureka. O – O
visibility at Eureka; never would have done it on my own. But the instructor made it look easy. Full power, set up a gradual climb until out of the over cast
and then turn east. I was not certain of the legality of such a take off. The CFI assured me the take off we performed was fully legal. I do not remember how, but remember he said it was in a small aircraft. Exhilarating, to say the least. The instructor did announce our departure on Unicom; which I have followed in the future. I believe I could do again on my own, but the situation has never arose, thank goodness. We took off heading north on an instrument departure at Eureka, CA. Probably nearly common place in Eureka with over cast nearly every evening in the winter. And why the airport at Kneeland exists. On two or three occasions with 80 to 90% overcast, I have landed in Eureka, in the PM with a clear day above; announcing my intentions on the Unicom, going through the clouds on a normal downslope. Also exhiliarting. Small aircraft with low flying airspeeds makes it near easy; my take away. Landing at 70 knots with clouds is no worse than going down the freeway in the fog in an auto. Except it is rare to go 70 mph on a freeway in the fog in my experience; but is doable.
“I can’t imagine ever having to make an IFR departure”
…short of being Indiana Jones’ pilot in Raiders of the Lost Ark with the Hovitos Indians closing in with their poison dart blowguns and spears or on Jimmy Buffet’s island when the volcano blows, I agree.
Ron,
Great article. One thing that’s always puzzled me about the rule that you may use an ODP without specific ATC permission (unless assigned a SID or radar vector) is the common ATC instruction at a non-tower field: “Entering controlled airspace fly heading XYZ”. This isn’t a SID or radar vector. Yes it’s a vector of sorts, but they don’t have you on radar yet. So I’d rather fly the ODP, but then I’m disobeying an ATC instruction, which is a violation. What’s your take on this situation?
Chris, as a former 141 Chief Instructor allow me to remind you that as the PIC, you have the final authority and responsibility as to the operation of your aircraft. Simply tell ATC that you will be flying the published DP. You’re not asking permission, you’re telling them what YOU ARE going to do.
And just to pile onto what Jetjock said, the reason why you tell them you are flying the ODP is so they can easily radar identify you when you do reach MVA. Most of the time though, you will hit MVA before flying the full ODP, so when you do check-in you will almost always be vectored onto the enroute structure as appropriate.
My take is just what you said — that’s neither a SID nor a radar vector so you are completely legal (not to mention safe, which always trumps legal) flying the published ODP.
ATC expects pilots to fly the ODP if published without a specific clearance to do so. Controlled airspace over most uncontrolled airports doesn’t start until 700agl. And ATC will not start vectoring until they have you identified on radar. Until then you are on your own to follow a published ODP for ground clearance, or maintain ground clearance visually if possible.
Great article. This is so frequently misunderstood by pilots..and controllers. I was one of each. I used to wonder what a pilot actually did when he/she got the clearance, “enter controlled airspace on heading…” Or if I assigned a heading on departure from and uncontrolled airport.
Hi Ron, shouldn’t this be 200 ft/NM instead of 200 fpm?
See the 2 quotes below.
Thanks
JetJock60 noted that the day the article dropped. Is that still not corrected? I’ll talk with Larry and Russ. Thanks for letting me know.