JOINT ADVANCED MULTI-ENGINE T-44A
altitude is published.
No 40:1 OIS Penetrations. If no obstacles penetrate the 40:1 obstacle identification surface (OIS), then a
minimum climb gradient of 200 ft/nm will ensure proper obstacle clearance. In this case, a "diverse
departure" is authorized.
Obstacles Penetrate the 40:1 OIS. 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. In some cases, IFR
departures are not authorized from specific runways.
Notification. 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 "T"
symbol is often referred to as the "Trouble T" since it usually means trouble for departing aircraft. The
presence of the "Trouble T" means you need to consult the separate listing in the front of the approach plate
titled, "IFR Takeoff Minimums and (Obstacle) Departure Procedures."
Methods to Avoid Obstacles. 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 PIC's responsibility to thoroughly review the published
instrument procedures in order to determine the appropriate method to be used. Each of these methods is
described in detail in the following paragraphs.
Basic Rules for all IFR Departures. Before moving on to describe the different methods of IFR departures,
let's summarize the basic rules applying to all IFR departure procedures. No matter what method of IFR
departure is used, these basic rules always apply:
Delay all turns until at least 400' above the airport elevation unless an early turn is specifically
required by the departure procedure.
Climb at a minimum of 200ft/nm unless a higher gradient is published.
C. Methods of IFR Departures. In general, there are four methods that may be used to depart an airport
under instrument flight rules (IFR): Diverse Departures, Departure Procedures (DPs), Standard Instrument
Departures (SIDs), and Specific ATC Departure Instructions.
(1) Diverse Departures.
What is a "Diverse Departure?" 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' above the field
elevation before executing any turns while maintaining a minimum climb gradient of 200 ft/nm
(unless a higher gradient is published) until reaching a minimum IFR altitude.
"Will ATC Clear Me for a Diverse Departure?" ATC will not specifically "clear" you for a diverse
departure. If you are "cleared as filed" and ATC does not issue you further instructions (by providing radar
vectors or assigning a SID/DP), then ATC expects you to execute a diverse departure. If a diverse
departure is not authorized for your runway, you must coordinate another runway or departure method with
ATC to depart the airport under IFR.
(2) IFR (Obstacle) Departure Procedures
Published instrument departure procedures assist pilots conducting IFR flight in avoiding
obstacles during climbout to minimum enroute altitude (MEA). Airports having penetrations to
the 40:1 OIS will normally have non-standard takeoff weather minimums as well as an IFR
Departure Procedure. This information is located in the front of DoD approach plates in the
section titled, "IFR Takeoff Minimums and (Obstacle) Departure Procedures." Every approach
chart and SID chart for an airport where takeoff minimums are not standard and/or departure
procedures are published is annotated with the symbol T . The use of this symbol indicates the
RADIO INSTRUMENTS STAGE