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U.S. Department

> of Transportation

**Federal Aviation**

**Administration**

January 13, 2006

Captain Pedro Rivas

Director, Charting and Instrument Procedures Committee

Air Line Pilots Association, International

535 Herndon Parkway

Post Office Box 1169

Herndon, VA 20172

RE: Climb Gradient Information for Air Carrier Pilots

Dear Captain Rivas,

We received a copy of your letter requesting a legal interpretation of
the Federal Aviation Regulations. In summary, you asked:

1.  whether an air carrier operating in accordance with parts 121 or 135
    is required to provide flight crewmembers with data necessary to
    assure that an aircraft can comply with the climb gradients
    specified in published instrument flight rules (IFR) departure
    procedures and standard instrument departure (SID) procedures; and

2.  whether pilots operating under parts 121 or 135 are required to
    follow a published IFR departure procedure even when Air Traffic
    Control (ATC) assigns a SID to a departing aircraft.

First, please accept our apologies for the delay in issuing a response
to your inquiry. As you are aware, the FAA has been working internally
and with the Government/Industry Aeronautical Charting Forum (Forum) on
this issue. We appreciate your efforts in resolving this aviation safety
matter.

Regarding the first issue, there is presently no requirement in the
Federal Aviation Regulations mandating air carriers or commercial
operators to provide climb gradient data to flight crewmembers.
Therefore, it would be necessary for the FAA to conduct rulemaking
proceedings in order to impose this requirement. Section 5 of the
Administrative Procedure Act defines rulemaking as the agency process
for formulating, amending, or repealing a rule.[^1] FAA rules are
subject to public notice and comment prior to implementation. You may
file a petition for rulemaking in accordance with 14 C.F.R. part 11.

Your second area of concern involved the requirement for pilots to
follow published IFR departure procedures. Specifically, you asked which
procedure a pilot should follow if ATC issues a SID that differs from
the published IFR departure procedure for a particular airport.

As an initial matter, it is helpful to clarify that a "published IFR
departure procedure" may be a SID developed for ATC purposes or an
obstacle departure procedure (ODP) developed for obstacle clearance
purposes. ODPs are developed by the Aviation System Standards Division
(AVN) within the FAA Flight Standards Service.[^2] According to Flight
Standards, ATC historically developed SIDs for purposes of expediting
air traffic and maintaining aircraft separation. SIDs did not contain an
assessment for obstacle clearance beyond the first en route navigational
fix. Instead, the obstacle assessment along the SID route was terminated
at the first en route airway fix even if the SID procedure had
transition routes beyond that point. The SIDs contained a standard 200
feet per nautical mile climb gradient that provided obstacle clearance
for most airports. Procedures requiring greater climb gradients were
specifically tested and documented in the Terminal Procedures
Publication as part of the procedure. Therefore, flight crews are
provided with adequate obstacle clearance climb gradients, even when
using a SID developed by ATC.

In recent years, AVN and ATC began developing ODPs that establish climb
gradients for obstacle clearance beyond the first en route navigational
fix. All airports with instrument approach procedures are assessed to
determine if an ODP should be published. ODPs are published for airports
with a required climb gradient of more than 200 feet per nautical mile
for obstacle clearance. The ODPs are valid for all directions of flight
unless otherwise stated in the ODP.

According to your letter, the question regarding which procedure a pilot
must follow stems from FAA Interpretation 1993-30.[^3] In that
interpretation, the FAA stated that part 121 or 135 operators are
required to follow "any published IFR departure procedure" regardless of
the weather conditions. A SID issued by ATC and an ODP developed by AVN
are both "published IFR departure procedures." Therefore, it is
consistent with the 1993 interpretation and regulatory requirements for
an operator to comply with either procedure. The pilot in command (PIC)
has the authority to determine which procedure is most appropriate based
on the circumstances of the flight. However, if the PIC desires to use
an ODP instead of the SID issued by ATC, the PIC must request an amended
clearance in accordance with § 91.123.

We trust that the foregoing interpretation is responsive to your
inquiry, and we apologize again for the delay in its issuance. This
interpretation was prepared by the Operations Law Branch of the Office
of the Chief Counsel, and coordinated with the Air Transportation and
Flight Operations Divisions of the Flight Standards Service. Please
contact us if we can be of further assistance.

Sincerely,

Rebecca MacPherson

Assistant Chief Counsel for Regulations

[^1]: 5 U.S.C. § 551 (2004).

[^2]: The FAA also notes that more restrictive departure procedures may
    be imposed on an air carrier via Operations Specifications. A
    carrier must always comply with the more restrictive procedures
    mandated by the Operations Specifications unless an emergency exists
    or the deviation is in response to a traffic alert and collision
    avoidance system resolution advisory. If a more restrictive
    procedure is mandated by the Operation Specifications, the pilot in
    command must seek an amended clearance from air traffic control.
    *See* 14 C.F.R. § 91.123 (2006).

[^3]: *See* Federal Aviation Decisions, published by West Publishing
    Company.