APPENDIX: IFR Departures

1. Why is knowing about IFR Departures so important?

Although we tend to think IFR approaches are more dangerous than IFR departures, there are some factors that make departures operations more dangerous. Usually airplanes are lightweight when landing compared to full weight at takeoff so is more performance limited. Instrument approach procedures are usually more definite and clear as far as routing and altitudes compared to some confusing departure options. Lastly, during arrival, aircraft have more ‘escape’ options than during takeoff. You can always go around out of an approach but once you take off you are committed.

2. How do the TERPS survey a field for obstacles?

When an airport is first created it is a VFR airport until it is determined that IFR operations are necessary. An airfield is first evaluated for instrument departures after the first instrument approach is built.


In order to assess the airport for instrument departures, the TERPs specialist looks for obstacles along a 40:1 slope from the departure end of the runway (The 40:1 slope is equivalent to a 2.5% gradient or 152 feet per nautical mile).

Required Obstacle Clearance (ROC) In addition to climbing above the 40:1 OIS, TERPs also requires aircraft to outclimb any obstacle by a minimum of 24% of the required obstacle clearance gradient. IN ALL INSTANCES, a minimum of 48 feet per nautical mile ROC will be attained. For procedures that require a substantial climb gradient, the ROC will be greater than 48 feet per nautical mile. Unless a higher gradient is published, USAF aircraft are required to meet or exceed 200 feet per nautical mile on all IFR departures.

If obstacles penetrate the 40:1 OIS, US TERPs criteria allows the TERPs specialist to raise the OIS as high as 35 feet above the departure end of the runway (DER) elevation to clear the obstacles. Raising the OIS in this manner requires aircraft to comply with a “runway end crossing height” to ensure obstacle clearance. This runway end crossing height is also known to some as a “screen height.” There is no way to know if the FAA’s TERPs specialist raised the OIS or not; therefore, you must always plan for the worst case and cross the departure end of the runway at 35 feet or higher. USAF and USN procedures are a little different; they always begin the OIS at zero feet at the DER, and if a runway end crossing height is required, it will be printed on the procedure.: In the United States, if the procedure is produced by anyone (including Army) other than USAF/USN, you must plan to cross the DER at or above 35 feet unless a higher altitude is published

2. How do you know “who” produced the procedure?.

Look near the title for a parenthesis stating (USAF), (USN), (USA) or (FAA)

3. How do I know if there are obstacles that penetrated the OIS during the Survey?

If no obstacles penetrate the 40:1 obstacle identification surface (OIS), then a minimum climb gradient of 200 feet per nautical mile will ensure proper obstacle clearance. If any obstacles penetrate the 40:1 OIS, then the TERPs specialist must provide notification to the pilot as well as establish a method to avoid the obstacles. The TERPs specialist may fulfill this requirement using a variety of methods. On U.S. Government charts (FLIP, NOAA), the notification is provided by the placement of a special symbol on all of the IAPs and SIDs for the airport. The symbol is a white “T” on a black inverted triangle. The presence of the means you need to consult the separate listing in the front of the approach plate titled, “IFR Takeoff Minimums and (Obstacle) Departure Procedures.”

4. Now that I know there were obstacles, how do I know how to avoid them?

The TERPs specialist will attempt to provide a method to avoid obstacles during climb to the minimum enroute altitude. Usually, IFR departure procedures will be published either in graphic or textual form. Other procedures you may encounter are SIDs or Departure Procedures (DPs). Under certain circumstances, obstacle clearance may be provided by specific ATC departure instructions that may include the use of radar vectors. It is the responsibility of the PIC to thoroughly review the published instrument procedures in order to determine the appropriate method to be used.

Basic Rules for all IFR Departures:

·  Delay all turns until at least 400 feet above the airport elevation unless an early turn is specifically required by the departure procedure.

·  Climb at a minimum of 200 feet per nautical mile unless a higher gradient is published. Air Force aircraft must always meet or exceed the published climb gradient for the runway used with all engines operative.

Methods of IFR Departures. In general, there are five methods that may be used to depart an airport under instrument flight rules (IFR):

·  Diverse Departures

·  Obstacle Departure Procedures (ODPs)

·  Standard Instrument Departures (SIDs)

·  Specific ATC Departure Instructions (includes Radar Vectors)

·  Special Departure Procedures (SDPs) (for emergency use only)

·  Visual Climb Over Airport

Note: This does not restrict aircraft already airborne from departing IFR via the published missed approach procedure for the instrument approach being flown.

Diverse Departures. If the airport has at least one instrument approach procedure (IAP), and there are no published IFR departure procedures (because there were no penetrations to the 40:1 OIS), then an aircraft departing can ensure obstacle clearance by executing a “diverse departure.” In order to fly a diverse departure, fly runway heading until 400 feet above the field elevation before executing any turns while maintaining a minimum climb gradient of 200 feet per nautical mile until reaching a minimum IFR altitude. There are airports around the world where the diverse departure assessment has not been properly completed. At these airports, a diverse departure may not be authorized for certain runways. You will be notified via NOTAM or by a on the approach plates that is then explained in the front of the book under “IFR Takeoff Minimums and (Obstacle) Departure Procedures.” The statement will say, “Diverse Departure Not Authorized.” YOU MAY FLY a diverse departure if you have been: a) cleared as filed (and didn’t file a SID), b) ATC has not issued climbout instructions, and c) there is no ODP listed for your takeoff runway in the “IFR Takeoff Minimums and (Obstacle) Departure Procedures” section of an approach book.

Obstacle Departure Procedures. Airports having penetrations to the 40:1 OIS will normally have non-standard takeoff weather minimums as well as an Obstacle Departure Procedure. This information is located in the front of DoD approach plates in the section titled, “IFR Takeoff Minimums and (Obstacle) Departure Procedures.” The FAA’s “standard” takeoff weather minimums are defined in FAR 91.175: one statute mile visibility for aircraft with two engines or less and one-half statute mile for aircraft with more than two engines. USAF aircraft will not use FAA takeoff weather minimums; minimum weather for takeoff is determined by AFI 11-202, Vol 3 as supplemented by MAJCOM or MDS flight directives.

1.  The “Trouble T.” The approach chart and SID chart for each airport where takeoff minimums are not standard and/or departure procedures are published is annotated with a special symbol . The use of this symbol indicates that the separate listing in the front of the approach book should be consulted. The non-standard weather minimums and minimum climb gradients found in the front of the approach book also apply to SIDs/DPs and radar vector departures unless different minimums are specified on the SID.

When designing an Obstacle Departure Procedure, the most common four methods used by the TERPs specialist are: non-standard takeoff weather minimums, climb gradients, specific routing, or a combination of several methods. Don’t forget; in some cases, an IFR departure may not be authorized.

2.  Non-Standard Takeoff Weather Minimums. When obstacles penetrate the 40:1 OIS, non-standard takeoff weather minimums are normally provided for some pilots to “see-and-avoid” obstacles during departure. “See-and-avoid” is a type of “home field advantage” for pilots who are familiar with the airport’s obstacle environment and who are flying aircraft that are usually not capable of meeting the minimum climb gradient. USAF pilots may not depart an airfield using non-standard takeoff minimums in lieu of meeting required climb gradient. When non-standard takeoff minimums are published, with or without climb gradient, the PIC may not takeoff under the provisions of IFR unless 1) the departure procedure authorizes “standard” takeoff minimums with a climb gradient in lieu of the non-standard criteria or 2) with one engine inoperative the aircraft must be capable of being at or above the published non-standard takeoff minima ceiling requirement prior to crossing the departure end of the runway and continue climb profile that will vertically clear all obstacles and meet all engine operating climb gradient (200 ft/NM or published if higher).

3.  Minimum Climb Gradient. The TERPs specialist may also provide a minimum climb gradient for use with the FAA’s “standard” takeoff weather minimums. This is the type of IFR departure procedure most commonly used by USAF aircraft. Typically, the non-standard takeoff weather minimums will have an asterisk (*) leading you to a note which will say something like, “Or standard with minimum climb gradient of 300 ft/NM to 700 feet.” When using this type of IFR departure, just substitute your MAJCOM-directed takeoff weather minimums where you see the word “standard.” USAF aircraft must always meet or exceed the published climb gradient for the runway used with all engines operating (if no climb gradient is published, must be at least 200 ft/NM (3.3). For multi-engine aircraft with one engine inoperative, PIC must ensure the aircraft can vertically clear all obstacles along the planned departure route during all segments of the climb profile. Based on the type and priority of our mission flying the T-1, we ensure that we meet a minimum of 200 ft/NM or published climb gradient whether OEI or all engines operating. We never subtract 48 ft/NM if IFR.

4.  Specific Routing. A third method used by the TERPs specialist is to provide a specific route of flight, which will take the aircraft away from the obstacle. You have to be careful when using this type of IFR departure. Make sure there is no requirement to use a non-standard takeoff weather minimum in order to execute the procedure. A legitimate routing will not have a non-standard takeoff weather minimum published.

“NA” = NOT AUTHORIZED!
These two examples (a SID and an IFR departure procedure) show two airports with an IFR departure not authorized from at least one of its runways.
To the left, you may not depart IFR from South Lake Tahoe on Runway 18 using the SHOLE ONE DEPARTURE.
Above, the IFR departure procedure from Tonopah prohibits IFR departures from Runway 11 and Runway 29.
In the example below, you may not depart IFR (using any method to include radar vectors) from Runway 36 at Tupelo, MS.

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Combination of All Three Methods. Some IFR departure procedures use a combination of all three methods. Once again, make sure the procedure does not require the use of non-standard takeoff weather minimums.

IFR Departure Procedure Using Combination
At first glance, you may think you could use this IFR departure procedure; however, if you look closely, you’ll notice the procedure requires the use of non-standard takeoff weather minimums. For example, if you were planning to takeoff on Runway 7, the procedure requires you have 800-2 and still climb at 650 feet per nautical mile.
Since the procedure requires the use of “see-and-avoid,” it is not authorized for use by USAF aircraft. /

5.  Low Close-In Obstacles. The TERPs specialist is not allowed to publish climb gradients to heights 200 feet or less. These are typically obstacles which are very close to the runway and would create a very large climb gradient. Instead of publishing a climb gradient, the TERPs specialist will publish a NOTE informing you of the height and location of the obstacles. In addition to complying with the published climb gradient, you must also ensure you can clear any obstacles published in this type of NOTE.

6.  “Will ATC Clear Me for an IFR Departure Procedure?” In most situations, ATC will not specifically clear you for an IFR departure procedure. If you are “cleared as filed” and ATC does not issue you further instructions (by providing radar vectors or assigning a SID/DP), then you are expected to fly the published instrument departure procedure for the runway used. AFI 11-202, Vol 3, states, “Unless otherwise cleared by ATC, pilots will fly the published instrument departure procedure for the runway used.”: There is one exception: If you are departing an airport, and pilot compliance with the IFR departure procedure is necessary for traffic separation, then ATC may include the IFR departure procedure in your ATC clearance.

7.  How Do I File an IFR Departure Procedure? At the time of this writing, there is no written guidance on how to “file” an IFR departure procedure although the AIM states, “any published DP may be filed and flown.” . If you want ATC to know you are planning to fly the IFR departure procedure, you’ll have to tell them. This is not a required call; however, in some situations (for example, a busy terminal area), it may be a good idea to give the controller a “heads-up.” There are some airports which will provide obstacle clearance via a SID/DP instead of establishing an IFR departure procedure. You will be notified via NOTAM or by a statement in the front of the book under the section titled, “IFR Takeoff Minimums and (Obstacle) Departure Procedures.” The statement will say, “RWY XX, use published DP for obstacle avoidance.”