Helicopter IFR Procedures: Understanding IFR Departures
One of the most common misconceptions among pilots who are gaining experience is that an IFR clearance provides obstacle protection from the moment the aircraft leaves the ground.
It doesn’t.
Every IFR departure begins with one simple question:
How will I maintain obstacle clearance?
The answer depends on the type of departure being flown and the procedures that have been developed for that airport. Understanding those procedures is one of the most important responsibilities of an instrument pilot.
Who Designs These Procedures?
Instrument departure procedures are not created by individual controllers or airport managers. They are developed by FAA or, in some cases, commercial procedure designers using the United States Standard for Terminal Instrument Procedures (TERPS).
TERPS is a comprehensive set of engineering criteria used to design instrument departures, approaches, holding patterns, and other IFR procedures. It considers aircraft performance, navigation accuracy, terrain, obstacles, and established clearance margins to produce standardized procedures that can be safely flown by any pilot who meets the published requirements.
As pilots, we don’t need to understand TERPS calculations. We simply need to appreciate that a published IFR departure is an engineered solution to an obstacle clearance “geometry problem.”
Standard Diverse Departures
Before publishing an instrument departure procedure, TERPS specialists perform what is known as a Diverse Departure Assessment.
If there is no terrain or obstacles that penetrate the protected space (e.g., require special routing or a climb gradient greater than the standard 40:1 – 152 feet per nautical mile) the airport qualifies for a standard diverse departure.
A standard diverse departure assumes the aircraft will depart from the runway, climb to 35’ before the departure end of the runway (DER), then maintain runway heading until reaching at least 400’ above airport elevation, and achieve a minimum climb gradient of 200 feet per nautical mile.
Only after reaching 400 feet above airport elevation may the pilot begin turning in any direction to remain within the protected obstacle clearance surfaces established by TERPS.
A standard diverse departure is what is expected in the absence of alternate takeoff minimums or a departure procedure because the TERPS evaluation of the airport has determined that if you follow these standard diverse departure assumptions, no special routing or climb performance is necessary to safely clear obstacles.
This is an important distinction for helicopter pilots.
Many of us routinely make turns shortly after liftoff during VFR operations. While that may be perfectly acceptable in visual conditions, it does not satisfy the assumptions of a standard diverse departure. Unless another published procedure authorizes it, obstacle protection assumes you will continue on the runway heading until reaching 400 feet above airport elevation before beginning your turn.
Alternative Takeoff Minimums
So how do you know when you should review the departure procedures for an airport?
Back in the day, before electronic flight bags (EFBs) and flight planning software, I started by looking at the approach plates at the airport I was departing which would inform me of my options if I had to return to the field. More importantly, I would look for the “Trouble T” symbol (a black inverted triangle with a white “T” printed on the instrument approach chart) published on the airport’s instrument approach procedures.
Whenever I saw that symbol, I knew there was additional information I needed to review before departure, and I would subsequently review the “Takeoff Minimums and (Obstacle) Departure Procedures” section of the Terminal Procedures Publication.
The “Trouble T” does not necessarily mean an Obstacle Departure Procedure exists. It simply tells you that the airport has additional departure information that may include non-standard takeoff minimums (ceiling/visibility and/or a rate of climb), an Obstacle Departure Procedure, close in obstacles, or all three.
All this critical information can now be found in the departure tab of the airport information in the ForeFlight app.
To guarantee obstacle clearance you must meet the specific climb gradients, departure routing, or other considerations necessary to safely avoid terrain and obstacles.
Three more quick notes about the Takeoff Minimums section –
- The climb gradient is based on distance over the ground (i.e., ground speed). Winds matter.
- This section may also include pilot notification of a Diverse Vector Area (DVA) which informs pilots that headings will be assigned by ATC to avoid obstacles.
- The non-standard takeoff minimums section also includes what the FAA refers to as “low, close in obstacles” –
- Low, close-in obstacles are obstacles located within 1 NM of the Departure End of Runway (DER) and penetrate the 40:1 Obstacle Clearance Surface (OCS). These obstacles are typically less than 200 feet above the DER elevation and are considered “low” because they only affect the initial climb segment immediately after takeoff. The standard required obstacle clearance of 48 feet per NM would necessitate a climb gradient exceeding 200 feet per NM for a very short distance, which is impractical to publish as a standard climb requirement.
- It has been my experience that these “low, close in obstacles” can create a lot of “noise” that operators must sift through to ensure that there are no other restrictions or requirements.
- Low, close-in obstacles are obstacles located within 1 NM of the Departure End of Runway (DER) and penetrate the 40:1 Obstacle Clearance Surface (OCS). These obstacles are typically less than 200 feet above the DER elevation and are considered “low” because they only affect the initial climb segment immediately after takeoff. The standard required obstacle clearance of 48 feet per NM would necessitate a climb gradient exceeding 200 feet per NM for a very short distance, which is impractical to publish as a standard climb requirement.
Standard Instrument Departures (SIDs)
A Standard Instrument Departure (SID) serves two purposes.
First, it provides obstacle clearance.
Second, it organizes traffic flow for Air Traffic Control.
SIDs reduce radio communication and allow controllers to move aircraft efficiently through busy airspace.
Because a SID is an ATC procedure, you must receive and accept an ATC clearance before flying it. Once assigned, it becomes part of your IFR clearance.
10-20 years ago, ATC generally did not want helicopters on SIDs. Since the slow helicopters were just going to jam up their traffic flow, they would provide a departure that kept the helicopter clear of the SID. However, as airspace has become more congested, a SID is often the only means for any aircraft to depart while keeping other arrivals and departures orderly. Therefore, I have increasingly been asked to fly SIDs in a helicopter, and I’ve grown to expect one when leaving a busy terminal area.
Obstacle Departure Procedures (ODPs)
An Obstacle Departure Procedure (ODP) serves a slightly different purpose.
Its main purpose is obstacle clearance.
Unlike a SID, traffic flow or controller workload are a secondary considerations.
One of the most misunderstood aspects of an ODP is that you do not need ATC to assign it.
If an ODP is published and you determine it is appropriate for your departure, you may fly it without an ATC clearance.
That said, communication is still important.
If you intend to fly the published ODP, let ATC know when you receive your clearance or on initial contact with departure or center. Doing so increases controller situational awareness and manages controller expectations.
ATC is responsible for aircraft separation.
You remain responsible for obstacle clearance unless ATC assigns an alternate procedure that specifically provides it.
Helicopter-Specific Departure Procedures
Many helicopter pilots are surprised to learn that there are COPTER SIDs and COPTER ODPs at some locations.
These procedures are designed specifically around helicopter performance and operating characteristics. They may include lower airspeeds, steeper climb gradients, unique routing, or transitions that would be impractical for fixed-wing aircraft.
Although they are far less common than standard procedures, every IFR helicopter pilot should know they exist and look for them during preflight planning.
We’ll devote an entire article to helicopter-specific departure procedures and point-in-space copter procedures in a future post.
Airports Without Published Instrument Procedures
This is where helicopter pilots should exercise the greatest caution.
We routinely operate from hospital helipads, remote landing zones, utility sites, private heliports, and airports that many IFR airplanes would never consider using.
In many cases, pilots can legally depart IFR. However, receiving an IFR clearance does not mean the departure path has been evaluated for obstacle clearance.
If an airport has no published instrument procedures, the departure has not been engineered through the TERPS process. Terrain, towers, and other obstacles must be identified, and the courses and climb performance necessary to avoid them are entirely the pilot’s responsibility.
Before climbing into the clouds, the pilot must have a plan for safely transitioning from the surface into the IFR system.
The Big Picture
Every IFR departure should begin with one simple question:
Where am I getting my obstacle clearance?
Sometimes the answer is a standard diverse departure or a vector on departure.
Sometimes it’s a SID.
Sometimes it’s an ODP.
Sometimes it’s a helicopter-specific departure procedure.
And sometimes there is no published procedure at all, leaving the responsibility squarely on the pilot.
IFR pilots should never assume obstacle protection.
Before every departure into the clouds, they know exactly where it comes from.